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Molecules, Volume 17, Issue 2 (February 2012), Pages 1138-2270

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Editorial

Jump to: Research, Review

Open AccessEditorial Sustained Growth of the Impact Factors of MDPI Open Access Journals
Molecules 2012, 17(2), 1354-1356; doi:10.3390/molecules17021354
Received: 2 January 2012 / Accepted: 2 February 2012 / Published: 2 February 2012
PDF Full-text (146 KB)
Abstract
Following the tradition established during the past two years [1,2], we are pleased to report the newly released Impact Factors of MDPI open access journals by the means of an editorial. This year’s edition of the Journal Citation Reports (JCR), which is [...] Read more.
Following the tradition established during the past two years [1,2], we are pleased to report the newly released Impact Factors of MDPI open access journals by the means of an editorial. This year’s edition of the Journal Citation Reports (JCR), which is published annually by Thomson Reuters, includes seven journals published by MDPI, including three that received their first official Impact Factors – Energies, Entropy, and more surprisingly Viruses – the latest with citation data from 2009 only. We are pleased to announce that the continued growth in Impact Factors reported during the past two years has been sustained, and Impact Factors of MDPI journals continue on a growth path. Table 1 reports the latest Impact Factors for 2010. Figure 1 graphically depicts the evolution of the Impact Factors for the four MDPI open access journals that have received Impact Factors in the past. Table 2 reports the ranking of the MDPI journals within the subject categories of the Science Citation Index Expanded (SCIE). [...] Full article
Open AccessEditorial Molecules Best Paper Award 2012
Molecules 2012, 17(2), 1795-1796; doi:10.3390/molecules17021795
Received: 7 February 2012 / Revised: 8 February 2012 / Accepted: 9 February 2012 / Published: 10 February 2012
PDF Full-text (270 KB)
Abstract
Molecules starts to institute the “Best Paper” award to recognize these outstanding papers in the area of natural products, medicinal chemistry and molecular diversity published in Molecules. We are pleased to announce the first “Molecules Best Paper Award” for 2012. Nominations [...] Read more.
Molecules starts to institute the “Best Paper” award to recognize these outstanding papers in the area of natural products, medicinal chemistry and molecular diversity published in Molecules. We are pleased to announce the first “Molecules Best Paper Award” for 2012. Nominations were selected by the editor-in-chief and selected editorial board members from all the papers published in 2008. [...] Full article
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Research

Jump to: Editorial, Review

Open AccessArticle Novel Cationic Carotenoid Lipids as Delivery Vectors of Antisense Oligonucleotides for Exon Skipping in Duchenne Muscular Dystrophy
Molecules 2012, 17(2), 1138-1148; doi:10.3390/molecules17021138
Received: 25 October 2011 / Revised: 22 December 2011 / Accepted: 4 January 2012 / Published: 24 January 2012
Cited by 10 | PDF Full-text (1278 KB)
Abstract
Duchenne Muscular Dystrophy (DMD) is a common, inherited, incurable, fatal muscle wasting disease caused by deletions that disrupt the reading frame of the DMD gene such that no functional dystrophin protein is produced. Antisense oligonucleotide (AO)-directed exon skipping restores the reading frame [...] Read more.
Duchenne Muscular Dystrophy (DMD) is a common, inherited, incurable, fatal muscle wasting disease caused by deletions that disrupt the reading frame of the DMD gene such that no functional dystrophin protein is produced. Antisense oligonucleotide (AO)-directed exon skipping restores the reading frame of the DMD gene, and truncated, yet functional dystrophin protein is expressed. The aim of this study was to assess the efficiency of two novel rigid, cationic carotenoid lipids, C30-20 and C20-20, in the delivery of a phosphorodiamidate morpholino (PMO) AO, specifically designed for the targeted skipping of exon 45 of DMD mRNA in normal human skeletal muscle primary cells (hSkMCs). The cationic carotenoid lipid/PMO-AO lipoplexes yielded significant exon 45 skipping relative to a known commercial lipid, 1,2-dimyristoyl-sn-glycero-3-ethylphosphocholine (EPC). Full article
(This article belongs to the Special Issue Carotenoids)
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Open AccessArticle Photocatalytic Degradation of Methyl Orange over Metalloporphyrins Supported on TiO2 Degussa P25
Molecules 2012, 17(2), 1149-1158; doi:10.3390/molecules17021149
Received: 21 November 2011 / Revised: 11 January 2012 / Accepted: 16 January 2012 / Published: 25 January 2012
Cited by 38 | PDF Full-text (470 KB)
Abstract
The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO2 (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts [...] Read more.
The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO2 (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV (DRS-UV-vis) and infrared spectra. Copper porphyrin-sensitized TiO2 photocatalyst (CuP-TiO2) showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO) charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO2 catalyst due to the increase of induced interactions. Full article
(This article belongs to the Special Issue Tetrapyrroles, Porphyrins and Phthalocyanines)
Open AccessArticle Primary, Secondary Metabolites, H2O2, Malondialdehyde and Photosynthetic Responses of Orthosiphon stimaneus Benth. to Different Irradiance Levels
Molecules 2012, 17(2), 1159-1176; doi:10.3390/molecules17021159
Received: 14 November 2011 / Revised: 16 December 2011 / Accepted: 19 December 2011 / Published: 27 January 2012
Cited by 15 | PDF Full-text (239 KB)
Abstract
The resource availability hypothesis predicts an increase in the allocation to secondary metabolites when carbon gain is improved relative to nutrient availability, which normally occurs during periods of low irradiance. The present work was carried out to confirm this hypothesis by investigating [...] Read more.
The resource availability hypothesis predicts an increase in the allocation to secondary metabolites when carbon gain is improved relative to nutrient availability, which normally occurs during periods of low irradiance. The present work was carried out to confirm this hypothesis by investigating the effects of decreasing irradiance on the production of plant secondary metabolites (flavonoids and phenolics) in the herbal plant Orthosiphon stamineus, and to characterize this production by carbohydrate, H2O2, and malondialdehyde (MDA) levels, net photosynthesis, leaf chlorophyll content and carbon to nitrogen ratio (C/N). Four levels of irradiance (225, 500, 625 and 900 µmol/m2/s) were imposed onto two-week old seedlings for 12 weeks in a randomized complete block design experiment. Peak production of total flavonoids, phenolics, soluble sugar, starch and total non-structural carbohydrate ocurred under low irradiance of 225 µmol/m2/s, and decreased with increasing irradiance. The up-regulation of secondary metabolites could be explained by the concomitant increases in H2O2 and MDA activities under low irradiance. This condition also resulted in enhanced C/N ratio signifying a reduction in nitrogen levels, which had established significant negative correlations with net photosynthesis, total biomass and total chlorophyll content, indicating the possible existence of a trade-off between growth and secondary metabolism under low irradiance with reduced nitrogen content. The competition between total chlorophyll and secondary metabolites production, as exhibited by the negative correlation coefficient under low irradiance, also suggests a sign of gradual switch of investment from chlorophyll to polyphenols production. Full article
Open AccessArticle Mild and Efficient Winterfeldt Oxidation of 1,2,3,4-Tetrahydro-γ-carbolines for the Synthesis of Dihydropyrrolo[3,2-b]-quinolones and Pyrrolo[3,2-b]quinolones
Molecules 2012, 17(2), 1177-1190; doi:10.3390/molecules17021177
Received: 5 December 2011 / Revised: 15 January 2012 / Accepted: 17 January 2012 / Published: 30 January 2012
Cited by 2 | PDF Full-text (316 KB)
Abstract
The Winterfeldt oxidation (NaOH, DMF, air, rt) of substituted 1,2,3,4-tetrahydro-γ-carbolines has been developed, which provides a convenient and efficient method for the synthesis of the corresponding dihydropyrrolo[3,2-b]quinolones in moderate to excellent yields (38–94%). The generality and substrate scope of this reaction are [...] Read more.
The Winterfeldt oxidation (NaOH, DMF, air, rt) of substituted 1,2,3,4-tetrahydro-γ-carbolines has been developed, which provides a convenient and efficient method for the synthesis of the corresponding dihydropyrrolo[3,2-b]quinolones in moderate to excellent yields (38–94%). The generality and substrate scope of this reaction are explored and a possible mechanism is proposed. The results imply that electron-withdrawing groups on N2 of tetrahydro-γ-carbolines and N5-H are necessary. The synthesis of 5 or 7-substituted pyrrolo[3,2-b]quinolones in near quantitative yields was also achieved through deprotection and aromatization of N1-Boc-dihydropyrrolo[3,2-b]quinolones. Full article
Open AccessArticle Protective Effect of Salvia miltiorrhiza Extract Against Renal Ischemia-Reperfusion-Induced Injury in Rats
Molecules 2012, 17(2), 1191-1202; doi:10.3390/molecules17021191
Received: 24 December 2011 / Revised: 1 January 2012 / Accepted: 24 January 2012 / Published: 30 January 2012
Cited by 8 | PDF Full-text (458 KB)
Abstract
The present study investigates the effect of pre-treatment with Salvia miltiorrhiza ethanol extracts (SMEE) on renal function markers, immunity and antioxidant activities in renal ischemia and reperfusion (IR) rats. Wistar rat kidneys were subjected to 60 min of global ischemia at 37 [...] Read more.
The present study investigates the effect of pre-treatment with Salvia miltiorrhiza ethanol extracts (SMEE) on renal function markers, immunity and antioxidant activities in renal ischemia and reperfusion (IR) rats. Wistar rat kidneys were subjected to 60 min of global ischemia at 37 °C followed by 30 min of reperfusion, and were randomly assigned into the sham, IR model and three SMEE-treated groups (n = 8 per group). Results showed that high serum creatinin (Scr), blood urea nitrogen (BUN), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-α) and malondialhehyde (MDA) levels, and low antioxidant enzyme activities were observed in IR rats compared to the sham rats. Pre-treatment of Salvia miltiorrhiza ethanol extracts for 20 days prior to IR operation improved renal function, reduced IR induced renal inflammatory and oxidative injury. It is concluded that Salvia miltiorrhiza ethanol extracts could be beneficial in the treatment of renal ischemic injury. Full article
Open AccessArticle Phenolic Compounds Characterization and Biological Activities of Citrus aurantium Bloom
Molecules 2012, 17(2), 1203-1218; doi:10.3390/molecules17021203
Received: 14 November 2011 / Revised: 22 December 2011 / Accepted: 23 December 2011 / Published: 30 January 2012
Cited by 23 | PDF Full-text (454 KB)
Abstract
Citrus plants are known to possess beneficial biological activities for human health. In addition, ethnopharmacological application of plants is a good tool to explore their bioactivities and active compounds. This research was carried out to evaluate the phenolic and flavonoid analysis, antioxidant [...] Read more.
Citrus plants are known to possess beneficial biological activities for human health. In addition, ethnopharmacological application of plants is a good tool to explore their bioactivities and active compounds. This research was carried out to evaluate the phenolic and flavonoid analysis, antioxidant properties, anti inflammatory and anti cancer activity of Citrus aurantium bloom. The total phenolics and flavonoids results revealed that methanolic extract contained high total phenolics and flavonoids compared to ethanolic and boiling water extracts. The obtained total phenolics value for methanolic Citrus aurantium bloom extract was 4.55 ± 0.05 mg gallic acid equivalent (GAE)/g dry weight (DW), and for total flavonoids it was 3.83 ± 0.05 mg rutin equivalent/g DW. In addition, the RP-HPLC analyses of phenolics and flavonoids indicated the presence of gallic acid, pyrogallol, syringic acid, caffeic acid, rutin, quercetin and naringin as bioactive compounds. The antioxidant activity of Citrus aurantium bloom were examined by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay and the ferric reducing/antioxidant potential (FRAP). The free radical scavenging and ferric reducing power activities were higher for the methanolic extract of Citrus aurantium bloom at a concentration of 300 μg/mL, with values of 55.3% and 51.7%, respectively, as compared to the corresponding boiling water and ethanolic extracts, but the activities were lower than those of antioxidant standards such as BHT and α-tocopherol. Furthermore, the anti-inflammatory result of methanolic extract showed appreciable reduction in nitric oxide production of stimulated RAW 264.7 cells at the presence of plant extract. Apart from that, the anticancer activity of the methanolic extract was investigated in vitro against human cancer cell lines (MCF-7; MDA-MB-231), human colon adenocarcinoma (HT-29) and Chang cell as a normal human hepatocyte. The obtained result demonstrated the moderate to appreciable activities against all cell line tested and the compounds present in the extracts are non-toxic which make them suitable as potential therapeutics. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Modulation of the Differentiation of Dental Pulp Stem Cells by Different Concentrations of β-Glycerophosphate
Molecules 2012, 17(2), 1219-1232; doi:10.3390/molecules17021219
Received: 15 December 2011 / Revised: 17 January 2012 / Accepted: 18 January 2012 / Published: 31 January 2012
Cited by 9 | PDF Full-text (476 KB)
Abstract
Dentinogenesis is a necessary prerequisite for dental tissue engineering. One of the steps for dentinogenesis is to obtain large quantities of highly purified odontoblasts. Therefore, we have undertaken an experiment applying different concentrations of β-glycerophosphate (β-GP) to induce the differentiation of dental [...] Read more.
Dentinogenesis is a necessary prerequisite for dental tissue engineering. One of the steps for dentinogenesis is to obtain large quantities of highly purified odontoblasts. Therefore, we have undertaken an experiment applying different concentrations of β-glycerophosphate (β-GP) to induce the differentiation of dental pulp stem cells (DPSCs) in a long-term 28-day culture. In the meanwhile, we have studied the time- and maturation-dependent expression of matrix extracellular phosphoglycoprotein (MEPE) and that of the odontoblast-like marker-dentin sialoprotein (DSP), in order to investigate an optimized mineralized condition. Western blot results revealed that the expression of DSP became lower when accompanied by the increase of the β-GP concentration, and there was also an influence on MEPE expression when different concentrations of β-GP were applied. Meanwhile, the mineralized groups had an inhibitory function on the expression of MEPE as compared with the control group. Above all, all experimental groups successfully generated mineralized nodules by Alizarin Red S and the 5 mM β-GP group formed more mineralized nodules quantitated using the CPC extraction method. In conclusion, there is a significant modulation of the β-GP during the differentiation of the DPSCs. The degree of odontoblast differentiation is β-glycerophosphate concentration dependent. A low concentration of β-GP (5 mM) has been shown to be the optimal concentration for stimulating the maturation of the DPSCs. Moreover, MEPE accompanied with DSP clearly demonstrates the degree of the differentiation. Full article
Open AccessArticle Synthesis of Novel IP Agonists via N-Aminoethyl Cyclic Amines Prepared by Decarboxylative Ring-Opening Reactions
Molecules 2012, 17(2), 1233-1246; doi:10.3390/molecules17021233
Received: 7 December 2011 / Revised: 20 January 2012 / Accepted: 21 January 2012 / Published: 31 January 2012
PDF Full-text (445 KB)
Abstract
An efficient synthesis of a highly potent and selective IP (PGI2 receptor) agonist that is not structurally analogous to PGI2 is described. This synthesis is accomplished through the following key steps: Nucleophilic ring-opening of 3-(4-chlorophenyl)-oxazolidin-2-one prepared by a one-pot procedure [...] Read more.
An efficient synthesis of a highly potent and selective IP (PGI2 receptor) agonist that is not structurally analogous to PGI2 is described. This synthesis is accomplished through the following key steps: Nucleophilic ring-opening of 3-(4-chlorophenyl)-oxazolidin-2-one prepared by a one-pot procedure with 4-piperidinol and selective O-alkylation of 1-(2-(4-chlorophenylamino)ethyl)piperidin-4-ol. The obtained compound is a potent and selective IP agonist displaying a long duration of action. Full article
(This article belongs to the Special Issue Heterocycles)
Open AccessArticle Synthesis, Characterization and Cytotoxicity of New Rotundic Acid Derivatives
Molecules 2012, 17(2), 1278-1291; doi:10.3390/molecules17021278
Received: 5 December 2011 / Revised: 17 January 2012 / Accepted: 20 January 2012 / Published: 31 January 2012
Cited by 5 | PDF Full-text (299 KB)
Abstract
Rotundic acid (RA, 1), a natural compound, exhibits potent tumor cell growth inhibiting properties. To date there are no reports on derivatives of RA. Furthermore, the 28-COOH position of RA might make it unstable and induced serious gastrointestinal [...] Read more.
Rotundic acid (RA, 1), a natural compound, exhibits potent tumor cell growth inhibiting properties. To date there are no reports on derivatives of RA. Furthermore, the 28-COOH position of RA might make it unstable and induced serious gastrointestinal side effects when it was applied in vivo. Therefore, in order to explore and make use of this compound, eight new amino acid derivatives of RA at the 28-COOH position were synthesized and evaluated for their cytotoxicities in vitro on three tumor cell lines including A375, HepG2 and NCI-H446. As a result, a few of these new amino acid derivatives showed stronger cytotoxicity. Compound 5a was found to have the best inhibition activity on the three tested human tumor cell lines with IC50 values of less than 10 μM compared with RA treatment. Meanwhile, the cytotoxicity of compound 6b was significantly higher than that of RA on the A375 cell line and almost the same as RA on the HepG2 and NCI-H446 cell lines. Hence, compounds 5a and 6b may serve as potential lead compounds for the development of new anti-tumor drugs. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle Microwave-Assisted Synthesis of New Substituted Anilides of Quinaldic Acid
Molecules 2012, 17(2), 1292-1306; doi:10.3390/molecules17021292
Received: 21 December 2011 / Revised: 13 January 2012 / Accepted: 16 January 2012 / Published: 31 January 2012
Cited by 6 | PDF Full-text (284 KB) | Supplementary Files
Abstract
In this study a one step method for the preparation of substituted anilides of quinoline-2-carboxylic acid was developed. This efficient innovative approach is based on the direct reaction of an acid or ester with substituted anilines using microwave irradiation. The optimized method [...] Read more.
In this study a one step method for the preparation of substituted anilides of quinoline-2-carboxylic acid was developed. This efficient innovative approach is based on the direct reaction of an acid or ester with substituted anilines using microwave irradiation. The optimized method was used for the synthesis of a series of eighteen substituted quinoline-2-carboxanilides. The molecular structure of N-(4-bromophenyl)quinoline-2-carboxamide as a model compound was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group with four molecules within the unit cell and the total structure of the compound can be described as “a slightly screwed boat”. Full article
Open AccessArticle Effects of the Cyclin-Dependent Kinase 10 (CDK10) on the Tamoxifen Sensitivity of Keloid Samples
Molecules 2012, 17(2), 1307-1318; doi:10.3390/molecules17021307
Received: 12 December 2011 / Revised: 14 January 2012 / Accepted: 17 January 2012 / Published: 1 February 2012
PDF Full-text (447 KB)
Abstract
Cyclin-dependent kinase 10 (CDK10) is a cell cycle regulating protein kinase, which has just been discriminated in recent years. In this paper, mRNA and protein expression of CDK10 were first investigated by a comparative study between 23 human keloid tissue samples and [...] Read more.
Cyclin-dependent kinase 10 (CDK10) is a cell cycle regulating protein kinase, which has just been discriminated in recent years. In this paper, mRNA and protein expression of CDK10 were first investigated by a comparative study between 23 human keloid tissue samples and their adjacent normal skin. To further address its potential as a therapeutic target in the treatment of keloid, a plasmid expressing the CDK10 gene was transfected into keloid fibroblast. The effects on tamoxifen-induced apoptosis were then investigated using Western blot assay and flow cytometry. Results showed that there is a generally down-regulated expression of CDK10 in keloid compared to normal skin samples. Transfection with the recombinant CDK10 plasmid significantly decreased the viability of cells and increased the apoptosis rates. Tamoxifen sensitivity in keloid fibroblasts was observed after treatment with the recombinant CDK10 plasmid. The results suggested that CDK10 may play an important role in enhancement of tamoxifen efficiency, and its expression may have a synergistic effect on keloid treatments. Full article
Open AccessArticle Microfiltration Process by Inorganic Membranes for Clarification of TongBi Liquor
Molecules 2012, 17(2), 1319-1334; doi:10.3390/molecules17021319
Received: 30 December 2011 / Revised: 15 January 2012 / Accepted: 17 January 2012 / Published: 1 February 2012
PDF Full-text (4549 KB)
Abstract
Membrane separation is an alternative separation technology to the conventional method of filtration. Hence, it has attracted use in the purification and concentration of Chinese Herbal Medicine Extracts (CHMEs). The purpose of this work was to study the process of microfiltration of [...] Read more.
Membrane separation is an alternative separation technology to the conventional method of filtration. Hence, it has attracted use in the purification and concentration of Chinese Herbal Medicine Extracts (CHMEs). The purpose of this work was to study the process of microfiltration of Tongbi liquor (TBL), a popular Chinese herbal drink, using ceramic membranes. Zirconium oxide and aluminum oxide membranes with pore mean sizes of 0.2 μm and 0.05 μm, respectively, are used for comparisons in terms of flux, transmittance of the ingredients, physical-chemical parameters, removal of macromolecular materials and fouling resistance. The results show that 0.2 μm zirconium oxide membrane is more suitable. The stable permeate flux reaches 135 L·h−1·m−2, the cumulative transmittance of the indicator is 65.53%. Macromolecular materials, such as starch, protein, tannin, pectin and total solids were largely eliminated in retentate after filtration using 0.2 μm ZrO2 ceramic membrane, resulting in clearer TBL. Moreover, this work also reveals that continuous ultrasound could strengthen membrane process that the permeate flux increases significantly. This work demonstrates that the purification of CHME with ceramic membranes is possible and yielded excellent results. Full article
Open AccessArticle Understanding the Mechanism of the Intramolecular Stetter Reaction. A DFT Study
Molecules 2012, 17(2), 1335-1353; doi:10.3390/molecules17021335
Received: 22 December 2011 / Revised: 19 January 2012 / Accepted: 20 January 2012 / Published: 2 February 2012
Cited by 16 | PDF Full-text (345 KB)
Abstract
The mechanism of the N-heterocyclic carbene (NHC)-catalyzed intramolecular Stetter reaction of salicylaldehyde 1 to yield chromanone 3 has been theoretically studied at the B3LYP/6-31G** level. This NHC-catalyzed reaction takes place through six elementary steps, which involve: (i) formation of the Breslow [...] Read more.
The mechanism of the N-heterocyclic carbene (NHC)-catalyzed intramolecular Stetter reaction of salicylaldehyde 1 to yield chromanone 3 has been theoretically studied at the B3LYP/6-31G** level. This NHC-catalyzed reaction takes place through six elementary steps, which involve: (i) formation of the Breslow intermediate IN2; (ii) an intramolecular Michael-Type addition in IN2 to form the new C-C s bond; and (iii) extrusion of the NHC catalyst from the Michael adduct to yield chromanone 3. Analysis of the relative free energies in toluene indicates that while formation of Breslow intermediate IN2 involves the rate-determining step of the catalytic process, the intramolecular Michael-type addition is the stereoselectivity determining step responsible for the configuration of the stereogenic carbon a to the carbonyl of chromanone 3. An ELF analysis at TSs and intermediates involved in the Michael-type addition allows for the characterization of the electronic changes along the C-C bond-formation. Full article
(This article belongs to the Special Issue Carbene Complexes)
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Open AccessArticle GHGKHKNK Octapeptide (P-5m) Inhibits Metastasis of HCCLM3 Cell Lines via Regulation of MMP-2 Expression in in Vitro and in Vivo Studies
Molecules 2012, 17(2), 1357-1372; doi:10.3390/molecules17021357
Received: 5 December 2011 / Revised: 19 January 2012 / Accepted: 27 January 2012 / Published: 2 February 2012
Cited by 6 | PDF Full-text (1627 KB) | Correction | Supplementary Files
Abstract
P-5m, an octapeptide derived from domain 5 of HKa, was initially found to inhibit the invasion and migration of melanoma cells. The high metastatic potential of melanoma cells was prevented by the HGK motif in the P-5m peptide in vitro and in [...] Read more.
P-5m, an octapeptide derived from domain 5 of HKa, was initially found to inhibit the invasion and migration of melanoma cells. The high metastatic potential of melanoma cells was prevented by the HGK motif in the P-5m peptide in vitro and in an experimental lung metastasis model, suggesting that P-5m may play an important role in the regulation of tumor metastasis. The aim of this study was to measure the effect of P-5m on tumor metastasis of human hepatocarcinoma cell line (HCCLM3) in vitro and in vivo in a nude mouse model of hepatocellular carcinoma (HCC), and detect the mechanisms involved in P-5m-induced anti-metastasis. By gelatin zymography, matrix metallo-proteinases 2 (MMP-2) activity in HCCLM3 was dramatically diminished by P-5m peptide. In addition, the migration and metastasis of HCCLM3 cells was also inhibited by the peptide in vitro. In an orthotopic model of HCC in nude mice, P-5m treatment effectively reduced the lung metastasis as well as the expression of MMP-2 in the tumor tissues. Overall, these observations indicate an important role for P-5m peptide in HCC invasion and metastasis, at least partially through modulation MMP-2 expression. These data suggests that P-5m may have therapeutic potential in metastatic human hepatocarcinoma. Full article
Open AccessArticle Design, Synthesis and Anti-fibrosis Activity Study of N1-Substituted Phenylhydroquinolinone Derivatives
Molecules 2012, 17(2), 1373-1387; doi:10.3390/molecules17021373
Received: 27 December 2011 / Revised: 20 January 2012 / Accepted: 21 January 2012 / Published: 2 February 2012
Cited by 2 | PDF Full-text (275 KB)
Abstract
Pirfenidone (5-methyl-1-phenyl-2(1H)-pyridone, PFD) is a small-molecule compound acting on multiple targets involved in pathological fibrogenesis and is effective to increase the survival of patients with fibrosis, such as idiopathic pulmonary fibrosis. However, PFD is not active enough, requiring a high daily dose. [...] Read more.
Pirfenidone (5-methyl-1-phenyl-2(1H)-pyridone, PFD) is a small-molecule compound acting on multiple targets involved in pathological fibrogenesis and is effective to increase the survival of patients with fibrosis, such as idiopathic pulmonary fibrosis. However, PFD is not active enough, requiring a high daily dose. In this study, to keep the multiple target profiles, N1-substituted phenylhydroquinolinone derivatives, which retain the 1-phenyl-2(1H)-pyridone scaffold were designed and synthesized. The preliminary anti-fibrosis activities for all target compounds were evaluated on a NIH3T3 fibroblast cell line using MTT assay methods. Most compounds showed significant inhibition on NIH3T3 cell proliferation with a IC50 range of 0.09–26 mM, among which 5-hydroxy-1-(4'-bromophenyl)-5,6,7,8-tetrahydroquinolin-2(1H)-one (6j) displayed 13 times higher potency (IC50 = 0.3 mM) than that of AKF-PD (IC50 = 4.2 mM). These results suggest that N1-substituted phenylhydroquinolinone is a promising scaffold which can be applied for further investigation and for developing novel anti-fibrosis agents. Full article
(This article belongs to the Section Medicinal Chemistry)
Open AccessArticle Synthesis, Docking Studies and Biological Evaluation of Benzo[b]thiophen-2-yl-3-(4-arylpiperazin-1-yl)-propan-1-one Derivatives on 5-HT1A Serotonin Receptors
Molecules 2012, 17(2), 1388-1407; doi:10.3390/molecules17021388
Received: 29 December 2011 / Revised: 28 January 2012 / Accepted: 30 January 2012 / Published: 3 February 2012
Cited by 4 | PDF Full-text (341 KB)
Abstract
A series of novel benzo[b]thiophen-2-yl-3-(4-arylpiperazin-1-yl)-propan-1-one derivatives 6a–f, 7a–f and their corresponding alcohols 8a–f were synthesized and evaluated for their affinity towards 5-HT1A receptors. The influence of arylpiperazine moiety and benzo[b]thiophene ring substitutions on binding affinity was [...] Read more.
A series of novel benzo[b]thiophen-2-yl-3-(4-arylpiperazin-1-yl)-propan-1-one derivatives 6a–f, 7a–f and their corresponding alcohols 8a–f were synthesized and evaluated for their affinity towards 5-HT1A receptors. The influence of arylpiperazine moiety and benzo[b]thiophene ring substitutions on binding affinity was studied. The most promising analogue, 1-(benzo[b]thiophen-2-yl)-3-(4-(pyridin-2-yl)piperazin-1-yl)propan-1-one (7e) displayed micromolar affinity (Ki = 2.30 μM) toward 5-HT1A sites. Docking studies shed light on the relevant electrostatic interactions which could explain the observed affinity for this compound. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle A New Iridoid Glycoside from the Roots of Dipsacus asper
Molecules 2012, 17(2), 1419-1424; doi:10.3390/molecules17021419
Received: 13 January 2012 / Revised: 21 January 2012 / Accepted: 30 January 2012 / Published: 3 February 2012
Cited by 6 | PDF Full-text (223 KB)
Abstract
A new iridoid glycoside, named loganic acid ethyl ester (1), together with five known compounds: chlorogenic acid (2), caffeic acid (3), loganin (4), cantleyoside (5) and syringaresinol-4′,4′′-O-bis-β-D-glucoside (6) [...] Read more.
A new iridoid glycoside, named loganic acid ethyl ester (1), together with five known compounds: chlorogenic acid (2), caffeic acid (3), loganin (4), cantleyoside (5) and syringaresinol-4′,4′′-O-bis-β-D-glucoside (6) were isolated from the roots of Dipsacus asper. The structure of compound 1 was elucidated on the basis of detailed spectroscopic analyses. Lignan is isolated from Dipsacaceae species for the first time. Compounds 1, 4 and 5 had moderate neuroprotective effects against the Aβ25–35 induced cell death in PC12 cells. Full article
(This article belongs to the Section Natural Products)
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Open AccessArticle Total Synthesis and Antidepressant Activities of Laetispicine and Its Derivatives
Molecules 2012, 17(2), 1425-1436; doi:10.3390/molecules17021425
Received: 4 January 2012 / Revised: 16 January 2012 / Accepted: 30 January 2012 / Published: 3 February 2012
Cited by 2 | PDF Full-text (293 KB) | Supplementary Files
Abstract
The first total synthesis of laetispicine (1a), an amide alkaloid isolated from the stems of Piper laetispicum C.DC (Piperaceae), and the synthesis of some of its derivatives were described. Based on the evaluation of antidepressant activities in the forced swimming [...] Read more.
The first total synthesis of laetispicine (1a), an amide alkaloid isolated from the stems of Piper laetispicum C.DC (Piperaceae), and the synthesis of some of its derivatives were described. Based on the evaluation of antidepressant activities in the forced swimming test, compounds 1h and 1i were identified as potent and safe antidepressant lead compounds. Full article
Open AccessArticle The Sesquiterpenes β-Caryophyllene and Caryophyllene Oxide Isolated from Senecio salignus Act as Phytogrowth and Photosynthesis Inhibitors
Molecules 2012, 17(2), 1437-1447; doi:10.3390/molecules17021437
Received: 9 December 2011 / Revised: 26 January 2012 / Accepted: 1 February 2012 / Published: 6 February 2012
Cited by 11 | PDF Full-text (370 KB)
Abstract
The n-hexane extract of S. salignus plants inhibited ATP synthesis and two sesquiterpenes, the b-caryophyllene (1) and caryophyllene oxide (2) were isolated from this nonpolar fraction. Compound 1 inhibited by 42% the root elongation of Physalis ixocarpa seedlings at 50 µg/mL [...] Read more.
The n-hexane extract of S. salignus plants inhibited ATP synthesis and two sesquiterpenes, the b-caryophyllene (1) and caryophyllene oxide (2) were isolated from this nonpolar fraction. Compound 1 inhibited by 42% the root elongation of Physalis ixocarpa seedlings at 50 µg/mL and by 53% at 150 µg/mL, whereas at 150 µg/mL this compound only inhibited root elongation of Echinochloa crus-galli by 30%. On the other hand, compound 2 had no effect on either germination or root and stem growth of E. cruss galli and P. ixocarpa. However, 1 and 2 inhibited the dry biomass of P. ixocarpa plants grown for 18 days previous to treatment and it was found that 1 was the most active biomass inhibitor. The Chl a fluorescence transient in vivo experiment indicates that 1 (100 µg/mL) has a major effect at 72 h after treatment on leaves of P. ixocarpa plants by inhibiting photosystem II (PS II) transforming active reaction centers to “heat sinks” or the formation of silent reaction centers unable to reduce QA. b-Caryophyllene also induces chlorosis on treated leaves. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle A Method of Hepatocyte Extraction Conjugated with HPLC is Established for Screening Potential Active Components in Chinese Medicines—Probing Herba Artemisiae Scopariae as an Exemplifying Approach
Molecules 2012, 17(2), 1468-1482; doi:10.3390/molecules17021468
Received: 4 November 2011 / Revised: 12 January 2012 / Accepted: 13 January 2012 / Published: 6 February 2012
Cited by 3 | PDF Full-text (414 KB)
Abstract
In order to establish an effective and quick method for screening potential bioactive compounds in Traditional Chinese Medicines (TCMs), hepatocytes were employed for extracting either bifendate, a clinical medicine for liver diseases, or chemicals in Herba Artemisiae Scopariae (A. Scopariae), [...] Read more.
In order to establish an effective and quick method for screening potential bioactive compounds in Traditional Chinese Medicines (TCMs), hepatocytes were employed for extracting either bifendate, a clinical medicine for liver diseases, or chemicals in Herba Artemisiae Scopariae (A. Scopariae), a commonly used traditional Chinese medicine for remedying liver diseases such as hepatitis induced by viruses, chemicals or alcohol. After hepatocyte extraction the compounds were analyzed by HPLC, therefore this method was referrred to as hepatocyte extraction conjugated with HPLC (HE-HPLC). In the first part of this study, HE-HPLC showed that bifendate was extracted by hepatocytes and detected by HPLC-DAD which indicated the feasibility of this method. Then in the second part of the study, the potential active components in the A. scopariae extract were studied using HE-HPLC. Six chemicals in the A. scopariae extract, which could bind to hepatocytes in vitro, were detected by HPLC-DAD and three were identified as 7-hydroxy-coumarin (7-OH-C), capillartemisin A and 7-methoxy-coumarin, respectively. In vitro assays showed that 7-OH-C protected HL-7702 hepatocytes from H2O2 injury. The results indicated that these compounds could be extracted by hepatocytes, could be detected by HPLC and more importantly were bioactive. It is suggested that HE-HPLC is a useful method for screening potent active components in Chinese medicines used to treat liver diseases. Full article
Open AccessArticle Developing Fluorescent Hyaluronan Analogs for Hyaluronan Studies
Molecules 2012, 17(2), 1520-1534; doi:10.3390/molecules17021520
Received: 22 November 2011 / Revised: 2 February 2012 / Accepted: 3 February 2012 / Published: 7 February 2012
Cited by 7 | PDF Full-text (1122 KB)
Abstract
Two kinds of fluorescent hyaluronan (HA) analogs, one serving as normal imaging agent and the other used as a biosensitive contrast agent, were developed for the investigation of HA uptake and degradation. Our approach of developing HA imaging agents depends on labeling [...] Read more.
Two kinds of fluorescent hyaluronan (HA) analogs, one serving as normal imaging agent and the other used as a biosensitive contrast agent, were developed for the investigation of HA uptake and degradation. Our approach of developing HA imaging agents depends on labeling HA with varying molar percentages of a near-infrared (NIR) dye. At low labeling ratios, the hyaluronan uptake can be directly imaged while at high labeling ratios, the fluorescent signal is quenched and signal generation occurs only after degradation. It is found that the conjugate containing 1%–2% NIR dye can be used as a normal optical imaging agent, while bioactivable imaging agents are formed at 6% to 17% dye loading. It was determined that the conjugation of dye to HA with different loading percentages does not impact HA biodegradation by hyaluronidase (Hyal). The feasibility of using these two NIR fluorescent hyaluronan analogs for HA investigation was evaluated in vivo with optical imaging. The data demonstrates that the 1% dye loaded fluorescent HA can be used to monitor the behavior of HA and its fragments, whereas bioactivatable HA imaging agent (17% dye in HA) is more suitable for detecting HA fragments. Full article
Open AccessArticle Carotenoids of Lettuce (Lactuca sativa L.) Grown on Soil Enriched with Spent Coffee Grounds
Molecules 2012, 17(2), 1535-1547; doi:10.3390/molecules17021535
Received: 5 December 2011 / Revised: 28 January 2012 / Accepted: 3 February 2012 / Published: 7 February 2012
Cited by 22 | PDF Full-text (249 KB)
Abstract
The impact of spent coffee grounds on carotenoid and chlorophyll content in lettuce (Lactuca sativa L. var. capitata) was evaluated. A greenhouse pot experiment was conducted with spent coffee amounts ranging from 0% to 20% (v/v). All evaluated pigments increased [...] Read more.
The impact of spent coffee grounds on carotenoid and chlorophyll content in lettuce (Lactuca sativa L. var. capitata) was evaluated. A greenhouse pot experiment was conducted with spent coffee amounts ranging from 0% to 20% (v/v). All evaluated pigments increased proportionally to spent coffee amounts. Lutein and β-carotene levels increased up to 90% and 72%, respectively, while chlorophylls increased up to 61%. Biomass was also improved in the presence of 2.5% to 10% spent coffee, decreasing for higher amounts. Nevertheless, all plants were characterized by lower organic nitrogen content than the control ones, inversely to the spent coffee amounts, pointing to possible induced stress. Collected data suggests that plants nutritional features, with regards to these bioactive compounds, can be improved by the presence of low amounts of spent coffee grounds (up to 10%). This observation is particularly important because soil amendment with spent coffee grounds is becoming increasingly common within domestic agriculture. Still, further studies on the detailed influence of spent coffee bioactive compounds are mandatory, particularly regarding caffeine. Full article
(This article belongs to the Special Issue Carotenoids)
Open AccessArticle Phloxine B as a Probe for Entrapment in Microcrystalline Cellulose
Molecules 2012, 17(2), 1602-1616; doi:10.3390/molecules17021602
Received: 11 November 2011 / Revised: 26 January 2012 / Accepted: 2 February 2012 / Published: 7 February 2012
Cited by 7 | PDF Full-text (359 KB)
Abstract
The photophysical behaviour of phloxine B adsorbed onto microcrystalline cellulose was evaluated by reflectance spectroscopy and laser induced time-resolved luminescence in the picosecond-nanosecond and microsecond-millisecond ranges. Analysis of the absorption spectral changes with concentration points to a small tendency of the dye [...] Read more.
The photophysical behaviour of phloxine B adsorbed onto microcrystalline cellulose was evaluated by reflectance spectroscopy and laser induced time-resolved luminescence in the picosecond-nanosecond and microsecond-millisecond ranges. Analysis of the absorption spectral changes with concentration points to a small tendency of the dye to aggregate in the range of concentrations under study. Prompt fluorescence, phosphorescence and delayed fluorescence spectral decays were measured at room temperature and 77 K, without the need of sample degassing because cellulose protects triplet states from oxygen quenching. In all cases, spectral changes with time and lifetime distribution analysis were consistent with the dye coexisting in two different environments: dyes tightly entrapped between polymer chains in crystalline regions of cellulose showed longer fluorescence and phosphorescence lifetimes and more energetic triplet states, while dyes adsorbed in more amorphous regions of the support showed shorter lifetimes and less energetic triplet states. This behaviour is discussed in terms of the different dye-support interactions in both kinds of adsorption sites. Full article
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Open AccessArticle Enantioselective Synthesis of 2,2-Disubstituted Terminal Epoxides via Catalytic Asymmetric Corey-Chaykovsky Epoxidation of Ketones
Molecules 2012, 17(2), 1617-1634; doi:10.3390/molecules17021617
Received: 16 December 2011 / Revised: 23 January 2012 / Accepted: 31 January 2012 / Published: 7 February 2012
Cited by 7 | PDF Full-text (396 KB)
Abstract
Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li3-BINOL complex (LLB) is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in [...] Read more.
Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li3-BINOL complex (LLB) is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (97%–91% ee) and yield ( > 99%–88%) from a broad range of methyl ketones with 1–5 mol% catalyst loading. Enantioselectivity was strongly dependent on the steric hindrance, and other ketones, such as ethyl ketones and propyl ketones resulted in slightly lower enantioselectivity (88%–67% ee). Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
Open AccessArticle Prebiotic Activity of Polysaccharides Extracted from Gigantochloa Levis (Buluh beting) Shoots
Molecules 2012, 17(2), 1635-1651; doi:10.3390/molecules17021635
Received: 11 October 2011 / Revised: 28 December 2011 / Accepted: 13 January 2012 / Published: 7 February 2012
Cited by 9 | PDF Full-text (424 KB)
Abstract
Bamboo shoot crude polysaccharides (BSCP) extracted from the shoots of Gigantochloa levis gave about 3.27 ± 0.18% on dry basis and a very minute percentage of protein (0.02 ± 0.01%). The molecular weight of BSCP estimated by gel chromatography was found to [...] Read more.
Bamboo shoot crude polysaccharides (BSCP) extracted from the shoots of Gigantochloa levis gave about 3.27 ± 0.18% on dry basis and a very minute percentage of protein (0.02 ± 0.01%). The molecular weight of BSCP estimated by gel chromatography was found to be around 7.49 × 103 Da, while the molecular weights of purified fractions (F1 to F5) were around 1550.96, 1471.63, 1685.78, 1691.61 and 1551.67 Da, respectively. The FTIR spectrum of BSCP revealed the possibility that the extract contains β-glucan, which can be considered a valuable compound for the medical and food industries. These relate to the resistance of BSCP towards artificial human gastric juice which is more than 99%. Prebiotic activity tested using BSCP as a carbon source showed significant increase in the growth of B. animalis ATCC 1053, B. longum BB 536 and L. acidophilus ATCC 4356 as compared to the use of FOS. Survivality of S. choleraesuis JCM 6977 was found to be slower in both BSCP and FOS. Study conducted reflects a good sign for the BSCP to be exploited as a promising prebiotic. Full article
(This article belongs to the Special Issue Multicomponent Reaction)
Open AccessArticle Palynological Origin, Phenolic Content, and Antioxidant Properties of Honeybee-Collected Pollen from Bahia, Brazil
Molecules 2012, 17(2), 1652-1664; doi:10.3390/molecules17021652
Received: 22 December 2011 / Revised: 16 January 2012 / Accepted: 26 January 2012 / Published: 7 February 2012
Cited by 14 | PDF Full-text (350 KB)
Abstract
The aim of this study was to determine the palynological origin, phenolic and flavonoid content, and antioxidant properties of twenty-five samples of bee pollen harvested during a nine-month period (February–November) from the Canavieiras municipality (northeastern Brazil). Of the 25 samples analyzed, only [...] Read more.
The aim of this study was to determine the palynological origin, phenolic and flavonoid content, and antioxidant properties of twenty-five samples of bee pollen harvested during a nine-month period (February–November) from the Canavieiras municipality (northeastern Brazil). Of the 25 samples analyzed, only two (February 01 and 02) were heterofloral. The predominant pollens in the samples analyzed during that month were: Cecropia, Eucalyptus, Elaeis, Mimosa pudica, Eupatorium, and Scoparia. Ethyl acetate fractions were analyzed by HPLC-DAD. The flavonoids isoquercetin, myricetin, tricetin, quercetin, luteolin, selagin, kaempferol, and isorhamnetin were detected. The flavonoid present in all 22 samples was isolated and identified as isorhamnetin 3-O-b-neohesperidoside. The total phenolic contents determined using the Folin-Ciocalteu reagent ranged from 41.5 to 213.2 mg GAE/g. Antioxidant activities based on the 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2-azinobis 3-ethylbenzothiozoline-6-sulfonic acid (ABTS), and Fe2+ ion chelating activity assays were observed for all extracts, and correlated with the total phenolic content. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Chiral Flavanones from Amygdalus lycioides Spach: Structural Elucidation and Identification of TNFalpha Inhibitors by Bioactivity-guided Fractionation
Molecules 2012, 17(2), 1665-1674; doi:10.3390/molecules17021665
Received: 30 December 2011 / Revised: 31 January 2012 / Accepted: 1 February 2012 / Published: 8 February 2012
Cited by 9 | PDF Full-text (380 KB) | Supplementary Files
Abstract
Phytochemical investigation on the Amygdalus lycioides Spach branchelets resulted in the isolation of four chiral flavanones: (2R,3R)-Taxifolin, (2R,3R)-aromadendrin, (S)-5,7,3',5'-tetrahydroxyflavanone and (S)-naringenin. The flavanones were [...] Read more.
Phytochemical investigation on the Amygdalus lycioides Spach branchelets resulted in the isolation of four chiral flavanones: (2R,3R)-Taxifolin, (2R,3R)-aromadendrin, (S)-5,7,3',5'-tetrahydroxyflavanone and (S)-naringenin. The flavanones were isolated by semi-preparative HPLC, their structures elucidated based on spectroscopic data and their absolute configuration assigned. As a part of our ethnobotanical-directed search for novel TNFα inhibitors, the bioassay-guided fractionation of the n-hexane-acetone (n-Hex-Ac, 1:1 v/v) Amygdalus lycioides Spach branchelets extract was performed. In this way, (S)-naringenin was identified as the constituent responsible for the TNFα blocking effect, being effective in vitro and in vivo after oral administration. This is the first investigation on bioactive secondary metabolites of Amygdalus lycioides Spach branchelets. Full article
(This article belongs to the Section Natural Products)
Open AccessCommunication Multicomponent Synthesis of 3,6-Dihydro-2H-1,3-thiazine-2-thiones
Molecules 2012, 17(2), 1675-1685; doi:10.3390/molecules17021675
Received: 5 January 2012 / Revised: 20 January 2012 / Accepted: 29 January 2012 / Published: 8 February 2012
Cited by 8 | PDF Full-text (259 KB) | Supplementary Files
Abstract
Non-fused 3,6-dihydro-2H-1,3-thiazine-2-thiones constitute a so far rather unexplored class of compounds, with the latest report dating back more than two decades. Thiazine-2-thiones contain an endocyclic dithiocarbamate group, which is often found in pesticides, in substrates for radical chemistry and in [...] Read more.
Non-fused 3,6-dihydro-2H-1,3-thiazine-2-thiones constitute a so far rather unexplored class of compounds, with the latest report dating back more than two decades. Thiazine-2-thiones contain an endocyclic dithiocarbamate group, which is often found in pesticides, in substrates for radical chemistry and in synthetic intermediates towards thioureas and amidines. We now report the multicomponent reaction (MCR) of in situ-generated 1-azadienes with carbon disulfide. With this reaction, a one-step protocol towards the potentially interesting 3,6-dihydro-2H-1,3-thiazine-2-thiones was established and a small library was synthesized. Full article
(This article belongs to the Special Issue Multicomponent Reaction)
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Open AccessArticle Phytochemical and Antioxidant-Related Investigations on Bark of Abies spectabilis (D. Don) Spach. from Nepal
Molecules 2012, 17(2), 1686-1697; doi:10.3390/molecules17021686
Received: 23 January 2012 / Revised: 7 February 2012 / Accepted: 8 February 2012 / Published: 8 February 2012
Cited by 2 | PDF Full-text (217 KB) | Supplementary Files
Abstract
The bark of several coniferous species, a waste product of the timber industry, contains significant amounts of natural antioxidants. In our ongoing studies of Nepalese medicinal plants, we examined the bark from Abies spectabilis as the starting material for extracting antioxidant compounds. [...] Read more.
The bark of several coniferous species, a waste product of the timber industry, contains significant amounts of natural antioxidants. In our ongoing studies of Nepalese medicinal plants, we examined the bark from Abies spectabilis as the starting material for extracting antioxidant compounds. In vitro antioxidant activity evaluated by means of three antioxidant methods, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH), Briggs-Rauscher oscillating reaction (BR) and Trolox Equivalent Antioxidant Capacity (TEAC) and total phenol contents with the Folin-Ciocalteau reagent; the ferrous iron chelating capacity was also assessed. The methanol extract of A. spectabilis showed significant antioxidant activity and polyphenol contents (IC50 4.13 µg/mL, 0.20 μg/mL eq. resorcinol, 4.22 mM eq. Trolox, 3.9 µg/g eq. gallic Acid in the DPPH, BR, TEAC and Folin-Ciocalteau tests, respectively) and weak Fe2+ chelating capacity. Phytochemical studies were also carried out with 1D- and 2D NMR experiments and DI-ESI-MS, HPLC-DAD and LC-MSn measurements. Oligomeric C-type proanthocyanidins, mainly trimeric gallocatechin derivatives, were the most abundant compounds (16% of extract expressed as procyanindin B1). Gallocatechin oligomers (up to six units) and prodelphynidin-gallocatechin polymers were also identified in the extract. Prodelphynidin B4, cyclograndisolide and trans-docosanil ferulate were also isolated and characterized by NMR and MS spectroscopy. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Ergosterol-Induced Sesquiterpenoid Synthesis in Tobacco Cells
Molecules 2012, 17(2), 1698-1715; doi:10.3390/molecules17021698
Received: 23 November 2011 / Revised: 26 January 2012 / Accepted: 6 February 2012 / Published: 9 February 2012
Cited by 7 | PDF Full-text (350 KB) | Supplementary Files
Abstract
Plants have the ability to continuously respond to microbial signals in their environment. One of these stimuli is a steroid from fungal membranes, ergosterol, which does not occur in plants, but acts as a pathogen-associated molecular pattern molecule to trigger defence mechanisms. [...] Read more.
Plants have the ability to continuously respond to microbial signals in their environment. One of these stimuli is a steroid from fungal membranes, ergosterol, which does not occur in plants, but acts as a pathogen-associated molecular pattern molecule to trigger defence mechanisms. Here we investigated the effect of ergosterol on the secondary metabolites in tobacco (Nicotiana tabacum) cells by profiling the induced sesquiterpenoids. Suspensions of tobacco cells were treated with different concentrations (0–1,000 nM) of ergosterol and incubated for different time periods (0–24 h). Metabolites were extracted with a selective dispersive liquid-liquid micro-extraction method. Thin layer chromatography was used as a screening method for identification of sesquiterpenoids in tobacco extracts. Liquid chromatography coupled to mass spectrometry was used for quantitative and qualitative analyses. The results showed that ergosterol triggered differential changes in the metabolome of tobacco cells, leading to variation in the biosynthesis of secondary metabolites. Metabolomic analysis through principal component analysis-scores plots revealed clusters of sample replicates for ergosterol treatments of 0, 50, 150, 300 and 1,000 nM and time-dependent variation at 0, 6, 12, 18 and 24 h. Five bicyclic sesquiterpenoid phytoalexins, capsidiol, lubimin, rishitin, solavetivone and phytuberin, were identified as being ergosterol-induced, contributing to the altered metabolome. Full article
(This article belongs to the Special Issue Terpenoids)
Open AccessArticle Chemisorption and Reactions of Small Molecules on Small Gold Particles
Molecules 2012, 17(2), 1716-1743; doi:10.3390/molecules17021716
Received: 30 January 2012 / Revised: 1 February 2012 / Accepted: 2 February 2012 / Published: 9 February 2012
Cited by 22 | PDF Full-text (497 KB)
Abstract
The activity of supported gold particles for a number of oxidations and hydrogenations starts to increase dramatically as the size falls below ~3 nm. This is accompanied by an increased propensity to chemisorption, especially of oxygen and hydrogen. The explanation for these [...] Read more.
The activity of supported gold particles for a number of oxidations and hydrogenations starts to increase dramatically as the size falls below ~3 nm. This is accompanied by an increased propensity to chemisorption, especially of oxygen and hydrogen. The explanation for these phenomena has to be sought in kinetic analysis that connects catalytic activity with the strength and extent of chemisorption of the reactants, the latter depending on the electronic structure of the gold atoms constituting the active centre. Examination of the changes to the utilisation of electrons as particle size is decreased points to loss of metallic character at about 3 nm, as energy bands are replaced by levels, and a band gap appears. Detailed consideration of the Arrhenius parameters (E and ln A) for CO oxidation points clearly to a step-change in activity at the point where metallic character is lost, as opposed to there being a monotonic dependence of rate on a physical property such as the fraction of atoms at corners or edges of particles. The deplorable scarcity of kinetic information on other reactions makes extension of this analysis difficult, but non-metallic behaviour is an unavoidable property of very small gold particles, and therefore cannot be ignored when seeking to explain their exceptional activity. Full article
(This article belongs to the Special Issue Gold Catalysts)
Open AccessArticle The Incubation of 13a,17-Dihydroxystemodane with Cephalosporium aphidicola
Molecules 2012, 17(2), 1744-1750; doi:10.3390/molecules17021744
Received: 30 November 2011 / Revised: 19 January 2012 / Accepted: 3 February 2012 / Published: 9 February 2012
PDF Full-text (187 KB)
Abstract
The biotransformation of 13a,17-dihydroxystemodane (3) with the fungus Cephalosporium aphidicola afforded 13a,17,18-trihydroxystemodane (4), 3b,13a,17-tri-hydroxystemodane (5), 13a,17-dihydroxy-stemodan-18-oic acid (6), 3b,11β,13a,17-tetra-hydroxystemodane (7), 11β,13a,17,18-tetrahydroxystemodane (8) and 3b,13a,17,18-tetra-hydroxystemodane (9). The hydroxylation at [...] Read more.
The biotransformation of 13a,17-dihydroxystemodane (3) with the fungus Cephalosporium aphidicola afforded 13a,17,18-trihydroxystemodane (4), 3b,13a,17-tri-hydroxystemodane (5), 13a,17-dihydroxy-stemodan-18-oic acid (6), 3b,11β,13a,17-tetra-hydroxystemodane (7), 11β,13a,17,18-tetrahydroxystemodane (8) and 3b,13a,17,18-tetra-hydroxystemodane (9). The hydroxylation at C-18 of the substrate points to a biosynthetically-directed transformation, because aphidicolin (2) is hydroxylated at this carbon. However, the C-3(b) and C-11(b) hydroxylations seem to indicate a xenobiotic biotransformation. Full article
(This article belongs to the Special Issue Terpenoids)
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Open AccessArticle Design, Synthesis and Preliminary Pharmacological Evaluation of New Non-Steroidal Anti-Inflammatory Agents Having a 4-(Methylsulfonyl) Aniline Pharmacophore
Molecules 2012, 17(2), 1751-1763; doi:10.3390/molecules17021751
Received: 30 December 2011 / Revised: 20 January 2012 / Accepted: 20 January 2012 / Published: 10 February 2012
Cited by 3 | PDF Full-text (250 KB)
Abstract
A series of 4-(methylsulfonyl)aniline derivatives were synthesized in order to obtain new compounds as a potential anti-inflammatory agents with expected selectivity against COX-2 enzyme. In vivo acute anti-inflammatory activity of the final compounds 1114 was evaluated in rat using an [...] Read more.
A series of 4-(methylsulfonyl)aniline derivatives were synthesized in order to obtain new compounds as a potential anti-inflammatory agents with expected selectivity against COX-2 enzyme. In vivo acute anti-inflammatory activity of the final compounds 1114 was evaluated in rat using an egg-white induced edema model of inflammation in a dose equivalent to 3 mg/Kg of diclofenac sodium. All tested compounds produced significant reduction of paw edema with respect to the effect of propylene glycol 50% v/v (control group). Moreover, the activity of compounds 11 and 14 was significantly higher than that of diclofenac sodium (at 3 mg/Kg) in the 120–300 minute time interval, while compound 12 expressed a comparable effect to that of diclofenac sodium in the 60–240 minute time interval time, and compound 13 showed a comparable effect to that of diclofenac sodium at all experimental times. The result of this study indicates that the incorporation of the 4-(methylsulfonyl)aniline pharamacophore into naproxen, indomethacine, diclofenac and mefanamic acid maintained their anti-inflammatory activity and may increase selectivity towards the COX-2 enzyme which will be confirmed in the future by assessing COX-2: COX-1 inhibitory ratios using a whole blood assay. Full article
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Open AccessArticle Phenolic Compounds and Antioxidant Activities of Liriope muscari
Molecules 2012, 17(2), 1797-1808; doi:10.3390/molecules17021797
Received: 24 November 2011 / Revised: 24 January 2012 / Accepted: 31 January 2012 / Published: 10 February 2012
Cited by 18 | PDF Full-text (258 KB) | Supplementary Files
Abstract
Five phenolic compounds, namely N-trans-coumaroyltyramine (1), N-trans-feruloyltyramine (2), N-trans-feruloyloctopamine (3), 5,7-dihydroxy-8-methoxyflavone (4) and (3S)3,5,4′-trihydroxy-7-methoxy-6-methylhomoisoflavanone (5), were isolated from the fibrous roots [...] Read more.
Five phenolic compounds, namely N-trans-coumaroyltyramine (1), N-trans-feruloyltyramine (2), N-trans-feruloyloctopamine (3), 5,7-dihydroxy-8-methoxyflavone (4) and (3S)3,5,4′-trihydroxy-7-methoxy-6-methylhomoisoflavanone (5), were isolated from the fibrous roots of Liriope muscari (Liliaceae). Compounds 25 were isolated for the first time from the Liriope genus. Their in vitro antioxidant activities were assessed by the DPPH and ABTS scavenging methods with microplate assays. The structure-activity relationships of compounds 13 are discussed. Full article
Open AccessArticle Pressurized Hot Ethanol Extraction of Carotenoids from Carrot By-Products
Molecules 2012, 17(2), 1809-1818; doi:10.3390/molecules17021809
Received: 30 November 2011 / Revised: 26 January 2012 / Accepted: 1 February 2012 / Published: 10 February 2012
Cited by 22 | PDF Full-text (691 KB)
Abstract
Carotenoids are known for their antioxidant activity and health promoting effects. One of the richest sources of carotenoids are carrots. However, about 25% of the annual production is regarded as by-products due to strict market policies. The aim of this study was [...] Read more.
Carotenoids are known for their antioxidant activity and health promoting effects. One of the richest sources of carotenoids are carrots. However, about 25% of the annual production is regarded as by-products due to strict market policies. The aim of this study was to extract carotenoids from those by-products. Conventional carotenoid extraction methods require the use of organic solvents, which are costly, environmentally hazardous, and require expensive disposal procedures. Pressurized liquid extraction (PLE) utilizes conventional solvents at elevated temperatures and pressure, and it requires less solvent and shorter extraction times. The extraction solvent of choice in this study was ethanol, which is a solvent generally recognized as safe (GRAS). The extraction procedure was optimized by varying the extraction time (2–10 min) and the temperature (60–180 °C). β-Carotene was used as an indicator for carotenoids content in the carrots. The results showed that time and temperatures of extraction have significant effect on the yield of carotenoids. Increasing the flush volume during extraction did not improve the extractability of carotenoids, indicating that the extraction method was mainly desorption/diffusion controlled. Use of a dispersing agent that absorbs the moisture content was important for the efficiency of extraction. Analysing the content of β-carotene at the different length of extraction cycles showed that about 80% was recovered after around 20 min of extraction. Full article
(This article belongs to the Special Issue Carotenoids)
Open AccessArticle Chemical and Biological Analyses of the Essential Oils and Main Constituents of Piper Species
Molecules 2012, 17(2), 1819-1829; doi:10.3390/molecules17021819
Received: 20 December 2011 / Revised: 26 January 2012 / Accepted: 7 February 2012 / Published: 13 February 2012
Cited by 10 | PDF Full-text (187 KB)
Abstract
The essential oils obtained from leaves of Piper duckei and Piper demeraranum by hydrodistillation were analyzed by gas chromatography-mass spectrometry. The main constituents found in P. demeraranum oil were limonene (19.3%) and β-elemene (33.1%) and in P. duckei oil the major components [...] Read more.
The essential oils obtained from leaves of Piper duckei and Piper demeraranum by hydrodistillation were analyzed by gas chromatography-mass spectrometry. The main constituents found in P. demeraranum oil were limonene (19.3%) and β-elemene (33.1%) and in P. duckei oil the major components found were germacrene D (14.7%) and trans-caryophyllene (27.1%). P. demeraranum and P. duckei oils exhibited biological activity, with IC50 values between 15 to 76 μg mL−1 against two Leishmania species, P. duckei oil being the most active. The cytotoxicity of the essential oils on mice peritoneal macrophage cells was insignificant, compared with the toxicity of pentamidine. The main mono- and sesquiterpene, limonene (IC50 = 278 μM) and caryophyllene (IC50 = 96 μM), were tested against the strains of Leishmania amazonensis, and the IC50 values of these compounds were lower than those found for the essential oils of the Piper species. The HET-CAM test was used to evaluate the irritation potential of these oils as topical products, showing that these oils can be used as auxiliary medication in cases of cutaneous leishmaniasis, with less side effects and lower costs. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Two New Iridoid Glycosides from the Root Barks of Sambucus williamsii Hance
Molecules 2012, 17(2), 1830-1836; doi:10.3390/molecules17021830
Received: 26 December 2011 / Revised: 9 February 2012 / Accepted: 9 February 2012 / Published: 13 February 2012
Cited by 3 | PDF Full-text (217 KB)
Abstract
Two new iridoid glycosides, named williamsoside C (1) and williamsoside D (2) were isolated from the root barks of Sambucus williamsii Hance. Their structures were established on the basis of extensive spectroscopic analysis (1D, 2D NMR and HRESIMS) [...] Read more.
Two new iridoid glycosides, named williamsoside C (1) and williamsoside D (2) were isolated from the root barks of Sambucus williamsii Hance. Their structures were established on the basis of extensive spectroscopic analysis (1D, 2D NMR and HRESIMS) and chemical studies as α-D-glucopyranosyl (1→2)-β-D-fructofuranosyl (4→6)-β-morroniside (1) and 7β-O-ethyl morroniside-(6′-O-7′′)-β-morroniside (2), respectively. Full article
(This article belongs to the Section Natural Products)
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Open AccessArticle Cytotoxic Phenylpropanoids and a New Triterpene, Turformosinic Acid, from Turpinia formosana Nakai
Molecules 2012, 17(2), 1837-1851; doi:10.3390/molecules17021837
Received: 26 January 2012 / Revised: 6 February 2012 / Accepted: 7 February 2012 / Published: 14 February 2012
Cited by 5 | PDF Full-text (433 KB)
Abstract
One new phenylpropanoid, turformosin A (1), and one new triterpene, turformosinic acid (2), together with 16 known compounds, were isolated from the stems of Turpinia formosana Nakai. All structures were elucidated on the basis of spectroscopic analysis, including [...] Read more.
One new phenylpropanoid, turformosin A (1), and one new triterpene, turformosinic acid (2), together with 16 known compounds, were isolated from the stems of Turpinia formosana Nakai. All structures were elucidated on the basis of spectroscopic analysis, including 1D- and 2D-NMR techniques and MS analysis. Selected isolated compounds were evaluated for in vitro cytotoxicity against four human cancer cell lines and antioxidant scavenging effects on DPPH. (−)-(7′S,8′S)-threo-carolignan X (3) exhibited cytotoxicity against Hep2, WiDr, Daoy, and MCF-7 cell lines with ED50 values of 3.60, 4.45, 6.07, and 13.7 μg/mL, respectively. Turformosin A (1), (−)-(7′S,8′S)- threo-carolignan X (3), methoxyhydroquinone-4-β-d-glucopyranoside (5), and methoxy-hydroquinone-1-β-d-glucopyranoside (6), exhibited similar anti-oxidative activity. Hep2 cells treated with 10 μg/mL of 3 showed elevation of sub-G1 population (from 20% at 8 h to 60% at 48 h), and activation of caspase-9/caspase-3/PARP cascade. Compound 3 induced intrinsic apoptotic pathway in Hep2 cells with dose and time dependence (10 μg/mL for 8 h). Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Evaluation of the Antiproliferative Activity of the Leaves from Arctium lappa by a Bioassay-Guided Fractionation
Molecules 2012, 17(2), 1852-1859; doi:10.3390/molecules17021852
Received: 26 November 2011 / Revised: 17 January 2012 / Accepted: 1 February 2012 / Published: 14 February 2012
Cited by 10 | PDF Full-text (173 KB) | Supplementary Files
Abstract
Arctium lappa L. (Asteraceae) is used in folk medicine around the World, and shows several kinds of biological activity, particularly in vitro antitumor activity in different cell lines. This study evaluated the antiproliferative activity of the crude extract, semipurified fractions, and isolated [...] Read more.
Arctium lappa L. (Asteraceae) is used in folk medicine around the World, and shows several kinds of biological activity, particularly in vitro antitumor activity in different cell lines. This study evaluated the antiproliferative activity of the crude extract, semipurified fractions, and isolated compounds from the leaves of A. lappa, through bioassay-guided testing in Caco-2 cells. The crude extract was obtained with a 50% hydroethanolic extract and then partitioned with hexane, ethyl acetate, and n-butanol. The ethyl-acetate fraction (EAF) showed antiproliferative activity. This fraction was subjected to sequential column chromatography over silica gel to afford onopordopicrin (1), mixtures of 1 with dehydromelitensin-8-(4'-hydroxymethacrylate) (2), a mixture of 2 with dehydromelitensin (3), mixture of 1 with melitensin (4), dehydrovomifoliol (5), and loliolide (6). The compounds were identified by spectroscopic methods (NMR, MS) and comparison with literature data. This is the first description of compounds 2–5 from this species. The compounds tested in Caco-2 cells showed the following CC50 (µg/mL) values: 1: 19.7 ± 3.4, 1 with 2: 24.6 ± 1.5, 2 with 3: 27 ± 11.7, 1 with 4: 42 ± 13.1, 6 30 ± 6.2; compound 5 showed no activity. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle An Efficient Three Component One-Pot Synthesis of 5-Amino-7-aryl-7,8-dihydro-[1,2,4] triazolo[4,3-a]-pyrimidine-6-carbonitriles
Molecules 2012, 17(2), 1860-1869; doi:10.3390/molecules17021860
Received: 11 January 2012 / Revised: 30 January 2012 / Accepted: 30 January 2012 / Published: 14 February 2012
Cited by 7 | PDF Full-text (190 KB) | Supplementary Files
Abstract
A series of novel 5-amino-7-aryl-7,8-dihydro-[1,2,4] triazolo[4,3-a]-pyrimidine-6-carbonitriles were synthesized by a one-pot reaction of 3-amino-1,2,4-triazole, malononitrile and aryl aldehydes in the presence of 20 mol% NaOH in ethanol under heating or ultrasonic irradiation. The structures of the target compounds were confirmed by inspection [...] Read more.
A series of novel 5-amino-7-aryl-7,8-dihydro-[1,2,4] triazolo[4,3-a]-pyrimidine-6-carbonitriles were synthesized by a one-pot reaction of 3-amino-1,2,4-triazole, malononitrile and aryl aldehydes in the presence of 20 mol% NaOH in ethanol under heating or ultrasonic irradiation. The structures of the target compounds were confirmed by inspection of their 1H- NMR, 13C-NMR, IR and MS spectra. The advantages of this method are short reaction times, good yields, high selectivity and operational simplicity. Full article
(This article belongs to the Section Organic Synthesis)
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Open AccessArticle Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis
Molecules 2012, 17(2), 1870-1882; doi:10.3390/molecules17021870
Received: 27 October 2011 / Revised: 7 February 2012 / Accepted: 7 February 2012 / Published: 14 February 2012
Cited by 3 | PDF Full-text (322 KB)
Abstract
The potential of enzyme catalysis in organic solvents for synthetic applications has been overshadowed by the fact that their catalytic properties are affected by organic solvents. In addition, it has recently been shown that an enzyme’s initial activity diminishes considerably after prolonged [...] Read more.
The potential of enzyme catalysis in organic solvents for synthetic applications has been overshadowed by the fact that their catalytic properties are affected by organic solvents. In addition, it has recently been shown that an enzyme’s initial activity diminishes considerably after prolonged exposure to organic media. Studies geared towards understanding this last drawback have yielded unclear results. In the present work we decided to use electron paramagnetic resonance spectroscopy (EPR) to study the motion of an active site spin label (a nitroxide free radical) during 96 h of exposure of the serine protease subtilisin Carlsberg to four different organic solvents. Our EPR data shows a typical two component spectra that was quantified by the ratio of the anisotropic and isotropic signals. The isotropic component, associated with a mobile nitroxide free radical, increases during prolonged exposure to all solvents used in the study. The maximum increase (of 43%) was observed in 1,4-dioxane. Based on these and previous studies we suggest that prolonged exposure of the enzyme to these solvents provokes a cascade of events that could induce substrates to adopt different binding conformations. This is the first EPR study of the motion of an active-site spin label during prolonged exposure of an enzyme to organic solvents ever reported. Full article
(This article belongs to the Special Issue Enzyme-Catalyzed Reactions)
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Open AccessArticle A New Triterpene From Uncaria macrophylla and Its Antitumor Activity
Molecules 2012, 17(2), 1883-1889; doi:10.3390/molecules17021883
Received: 10 January 2012 / Revised: 3 February 2012 / Accepted: 7 February 2012 / Published: 14 February 2012
Cited by 6 | PDF Full-text (229 KB)
Abstract
On our ongoing investigation, a new oleanolic triterpene, 3β,6β,19α-trihydroxy-12-oleanen-28-oic acid (1) was obtained from the chloroform-soluble portion of the 90% alcohol-water extract of the stem bark of Uncaria macrophylla. Its structure was elucidated by extensive spectroscopic methods, including 1D and [...] Read more.
On our ongoing investigation, a new oleanolic triterpene, 3β,6β,19α-trihydroxy-12-oleanen-28-oic acid (1) was obtained from the chloroform-soluble portion of the 90% alcohol-water extract of the stem bark of Uncaria macrophylla. Its structure was elucidated by extensive spectroscopic methods, including 1D and 2D (1H-1H COSY, HSQC and HMBC) NMR and HR-ESI-MS. The cytotoxicities of the compound was evaluated against two cancer cell lines of MCF-7 and HepG2 by the MTT method, and the compound exhibited weak activities with the IC50 values of 78.2 µg/mL and 73.9 µg/mL. Full article
Open AccessArticle A New Class of Heterocycles: 1,4,3,5-Oxathiadiazepane 4,4-dioxides
Molecules 2012, 17(2), 1890-1899; doi:10.3390/molecules17021890
Received: 19 January 2012 / Revised: 6 February 2012 / Accepted: 8 February 2012 / Published: 14 February 2012
PDF Full-text (192 KB)
Abstract
This work reports the synthesis of novel 1,4,3,5-oxathiadiazepanes 4,4-dioxides from the reaction of N’-benzyl-N-(2-hydroxyethyl)-sarcosine or proline sulfamide with aromatic aldehydes under acid catalysis. To prepare the starting materials N-Boc-sulfamide derivatives of sarcosine or proline were alkylated with benzyl [...] Read more.
This work reports the synthesis of novel 1,4,3,5-oxathiadiazepanes 4,4-dioxides from the reaction of N’-benzyl-N-(2-hydroxyethyl)-sarcosine or proline sulfamide with aromatic aldehydes under acid catalysis. To prepare the starting materials N-Boc-sulfamide derivatives of sarcosine or proline were alkylated with benzyl alcohol under Mitsunobu reaction conditions, the Boc group was removed chemoselectively by acidolysis, and the resulting product reduced to the corresponding alcohol in good yields. Full article
(This article belongs to the Special Issue Heterocycles)
Open AccessArticle Synthesis and Characterization of Hybrid Molecularly Imprinted Polymer (MIP) Membranes for Removal of Methylene Blue (MB)
Molecules 2012, 17(2), 1916-1928; doi:10.3390/molecules17021916
Received: 15 December 2011 / Revised: 2 February 2012 / Accepted: 3 February 2012 / Published: 15 February 2012
Cited by 7 | PDF Full-text (944 KB)
Abstract
This work reports the synthesis and characterization of a hybrid molecularly imprinted polymer (MIP) membrane for removal of methylene blue (MB) in an aqueous environment. MB-MIP powders were hybridized into a polymer membrane (cellulose acetate (CA) and polysulfone (PSf)) after it was [...] Read more.
This work reports the synthesis and characterization of a hybrid molecularly imprinted polymer (MIP) membrane for removal of methylene blue (MB) in an aqueous environment. MB-MIP powders were hybridized into a polymer membrane (cellulose acetate (CA) and polysulfone (PSf)) after it was ground and sieved (using 90 µm sieve). MB-MIP membranes were prepared using a phase inversion process. The MB-MIP membranes were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Parameters investigated for the removal of MB by using membrane MB-MIP include pH, effect of time, concentration of MB, and selectivity studies. Maximum sorption of MB by PSf-MB-MIP membranes and CA-MB-MIP membranes occurred at pH 10 and pH 12, respectively. The kinetic study showed that the sorption of MB by MB-MIP membranes (PSf-MB-MIP and CA-MB-MIP) followed a pseudo-second-order-model and the MB sorption isotherm can be described by a Freundlich isotherm model. Full article
Open AccessArticle An Adaptive Single-Well Stochastic Resonance Algorithm Applied to Trace Analysis of Clenbuterol in Human Urine
Molecules 2012, 17(2), 1929-1938; doi:10.3390/molecules17021929
Received: 13 December 2011 / Revised: 22 January 2012 / Accepted: 2 February 2012 / Published: 15 February 2012
Cited by 6 | PDF Full-text (266 KB)
Abstract
Based on the theory of stochastic resonance, an adaptive single-well stochastic resonance (ASSR) coupled with genetic algorithm was developed to enhance the signal-to-noise ratio of weak chromatographic signals. In conventional stochastic resonance algorithm, there are two or more parameters needed to be [...] Read more.
Based on the theory of stochastic resonance, an adaptive single-well stochastic resonance (ASSR) coupled with genetic algorithm was developed to enhance the signal-to-noise ratio of weak chromatographic signals. In conventional stochastic resonance algorithm, there are two or more parameters needed to be optimized and the proper parameters values were obtained by a universal searching within a given range. In the developed ASSR, the optimization of system parameter was simplified and automatic implemented. The ASSR was applied to the trace analysis of clenbuterol in human urine and it helped to significantly improve the limit of detection and limit of quantification of clenbuterol. Good linearity, precision and accuracy of the proposed method ensure that it could be an effective tool for trace analysis and the improvement of detective sensibility of current detectors. Full article
(This article belongs to the Section Medicinal Chemistry)
Open AccessArticle Enhancement of Mechanical and Thermal Properties of Oil Palm Empty Fruit Bunch Fiber Poly(butylene adipate-co-terephtalate) Biocomposites by Matrix Esterification Using Succinic Anhydride
Molecules 2012, 17(2), 1969-1991; doi:10.3390/molecules17021969
Received: 13 December 2011 / Revised: 2 February 2012 / Accepted: 3 February 2012 / Published: 16 February 2012
Cited by 12 | PDF Full-text (3605 KB)
Abstract
In this work, the oil palm empty fruit bunch (EFB) fiber was used as a source of lignocellulosic filler to fabricate a novel type of cost effective biodegradable composite, based on the aliphatic aromatic co-polyester poly(butylene adipate-co-terephtalate) PBAT (EcoflexTM), as [...] Read more.
In this work, the oil palm empty fruit bunch (EFB) fiber was used as a source of lignocellulosic filler to fabricate a novel type of cost effective biodegradable composite, based on the aliphatic aromatic co-polyester poly(butylene adipate-co-terephtalate) PBAT (EcoflexTM), as a fully biodegradable thermoplastic polymer matrix. The aim of this research was to improve the new biocomposites’ performance by chemical modification using succinic anhydride (SAH) as a coupling agent in the presence and absence of dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as initiators. For the composite preparation, several blends were prepared with varying ratios of filler and matrix using the melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 (wt %) and characterized. The effects of fiber loading and coupling agent loading on the thermal properties of biodegradable polymer composites were evaluated using thermal gravimetric analysis (TGA). Scanning Electron Microscopy (SEM) was used for morphological studies. The chemical structure of the new biocomposites was also analyzed using the Fourier Transform Infrared (FTIR) spectroscopy technique. The PBAT biocomposite reinforced with 40 (wt %) of EFB fiber showed the best mechanical properties compared to the other PBAT/EFB fiber biocomposites. Biocomposite treatment with 4 (wt %) succinic anhydride (SAH) and 1 (wt %) dicumyl peroxide (DCP) improved both tensile and flexural strength as well as tensile and flexural modulus. The FTIR analyses proved the mechanical test results by presenting the evidence of successful esterification using SAH/DCP in the biocomposites’ spectra. The SEM micrograph of the tensile fractured surfaces showed the improvement of fiber-matrix adhesion after using SAH. The TGA results showed that chemical modification using SAH/DCP improved the thermal stability of the PBAT/EFB biocomposite. Full article
Open AccessArticle Allylic Alkylations Catalyzed By Palladium-Bis(oxazoline) Complexes Derived From Heteroarylidene Malonate Derivatives
Molecules 2012, 17(2), 1992-1999; doi:10.3390/molecules17021992
Received: 14 November 2011 / Revised: 19 January 2012 / Accepted: 6 February 2012 / Published: 17 February 2012
Cited by 8 | PDF Full-text (206 KB) | Supplementary Files
Abstract
A series of simple heteroarylidene malonate-type bis(oxazoline) ligands 4 and 5 were applied to the Palladium-catalyzed allylic alkylation reaction, and the ligand 4a bearing a phenyl group afforded excellent enantioselectivity (up to 96% ee) for the allylic alkylation product. Other [...] Read more.
A series of simple heteroarylidene malonate-type bis(oxazoline) ligands 4 and 5 were applied to the Palladium-catalyzed allylic alkylation reaction, and the ligand 4a bearing a phenyl group afforded excellent enantioselectivity (up to 96% ee) for the allylic alkylation product. Other substrates were also examined, giving the allylic alkylated products in high yield but with poor ee values. Full article
(This article belongs to the Section Organic Synthesis)
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Open AccessArticle Impact of Halogen Substituents on Interactions between 2-Phenyl-2,3-dihydroqulinazolin-4(1H)-one Derivatives and Human Serum Albumin
Molecules 2012, 17(2), 2000-2014; doi:10.3390/molecules17022000
Received: 16 December 2011 / Revised: 26 January 2012 / Accepted: 27 January 2012 / Published: 17 February 2012
Cited by 3 | PDF Full-text (583 KB) | Supplementary Files
Abstract
A novel type of 2-(un)substituted phenyl-2,3-dihydroquinazolin-4(1H)-one (DQL) derivatives were designed and synthesized to study the impact of halogen substituents on interactions between DQL and human serum albumin (HSA) by comparison methodology. The interactions between DQL and HSA were studied by [...] Read more.
A novel type of 2-(un)substituted phenyl-2,3-dihydroquinazolin-4(1H)-one (DQL) derivatives were designed and synthesized to study the impact of halogen substituents on interactions between DQL and human serum albumin (HSA) by comparison methodology. The interactions between DQL and HSA were studied by fluorescence spectroscopy. The intrinsic fluorescence of human serum albumin was quenched by DQL through a static quenching mechanism. Site marker competitive experiments showed that DQL bound to HSA in site II (subdomain IIIA). The binding constants, the numbers of binding sites and the thermodynamic parameters were measured too. The results indicated that the interactions were spontaneous, mainly through hydrophobic forces, and the substitution by halogen atoms in the benzene ring could increase the interactions between DQL and HSA. Furthermore, the binding affinity was enhanced gradually with the increasing of halogen atomic number. Full article
Open AccessArticle 3D-QSAR Studies of Dihydropyrazole and Dihydropyrrole Derivatives as Inhibitors of Human Mitotic Kinesin Eg5 Based on Molecular Docking
Molecules 2012, 17(2), 2015-2029; doi:10.3390/molecules17022015
Received: 7 February 2012 / Revised: 7 February 2012 / Accepted: 13 February 2012 / Published: 17 February 2012
Cited by 5 | PDF Full-text (501 KB)
Abstract
Human mitotic kinesin Eg5 plays an essential role in mitoses and is an interesting drug target against cancer. To find the correlation between Eg5 and its inhibitors, structure-based 3D-quantitative structure–activity relationship (QSAR) studies were performed on a series of dihydropyrazole and dihydropyrrole [...] Read more.
Human mitotic kinesin Eg5 plays an essential role in mitoses and is an interesting drug target against cancer. To find the correlation between Eg5 and its inhibitors, structure-based 3D-quantitative structure–activity relationship (QSAR) studies were performed on a series of dihydropyrazole and dihydropyrrole derivatives using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods. Based on the LigandFit docking results, predictive 3D-QSAR models were established, with cross-validated coefficient values (q2) up to 0.798 for CoMFA and 0.848 for CoMSIA, respectively. Furthermore, the CoMFA and CoMSIA models were mapped back to the binding sites of Eg5, which could provide a better understanding of vital interactions between the inhibitors and the kinase. Ligands binding in hydrophobic part of the inhibitor-binding pocket were found to be crucial for potent ligand binding and kinases selectivity. The analyses may be used to design more potent EG5 inhibitors and predict their activities prior to synthesis. Full article
(This article belongs to the Special Issue QSAR and Its Applications)
Open AccessArticle Kramecyne — A New Anti-inflammatory Compound Isolated from Krameria cytisoides
Molecules 2012, 17(2), 2049-2057; doi:10.3390/molecules17022049
Received: 13 February 2012 / Revised: 13 February 2012 / Accepted: 14 February 2012 / Published: 20 February 2012
Cited by 5 | PDF Full-text (328 KB)
Abstract
In the present work we describe the structure and anti-inflammatory activity of a new compound, kramecyne, isolated from a methanol extract of Krameria cytisoides (Krameriaceae). The structure of kramecyne was determined by IR, NMR, MS, and elemental analysis, which indicated that the [...] Read more.
In the present work we describe the structure and anti-inflammatory activity of a new compound, kramecyne, isolated from a methanol extract of Krameria cytisoides (Krameriaceae). The structure of kramecyne was determined by IR, NMR, MS, and elemental analysis, which indicated that the structure corresponded to a hexamer of cyclic peroxide monomers. This compound exhibited good anti-inflammatory activity in the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema (51.8 ± 6.9% inhibition) and carrageenan-induced rat paw edema models at doses of 50 mg/kg. The compound significantly reduced edema to 63.1% after 1.0 h, and the effect was unchanged for 5 h. Kramecyne did not present acute toxicity, even at doses of 5,000 mg/kg. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Volatile Organic Compounds from Centaurium erythraea Rafn (Croatia) and the Antimicrobial Potential of Its Essential Oil
Molecules 2012, 17(2), 2058-2072; doi:10.3390/molecules17022058
Received: 18 January 2012 / Revised: 9 February 2012 / Accepted: 13 February 2012 / Published: 20 February 2012
Cited by 1 | PDF Full-text (289 KB)
Abstract
GC and MS were used for the analysis of Croatian Centaurium erythraea Rafn essential oil (obtained by hydrodistillation) and headspace (applying headspace solid-phase microextraction). The headspace contained numerous monoterpene hydrocarbons (the major ones were terpinene-4-ol, methone, p-cymene, γ-terpinene and limonene). Oxygenated [...] Read more.
GC and MS were used for the analysis of Croatian Centaurium erythraea Rafn essential oil (obtained by hydrodistillation) and headspace (applying headspace solid-phase microextraction). The headspace contained numerous monoterpene hydrocarbons (the major ones were terpinene-4-ol, methone, p-cymene, γ-terpinene and limonene). Oxygenated monoterpenes were present in the headspace and oil, while 1,8-cineole, bornyl acetate and verbenone were present only in the headspace. High headspace percentages of toluene and naphthalene were found, followed by hemimellitene. Lot of similarities were observed with Serbian C. erythraea oil [neophytadiene (1.4%), thymol (2.6%), carvacrol (6.1%) and hexadecanoic acid (5.7%)], but different features were also noted such as the presence of menthol, menthone and phytone. The oil fractionation enabled identification of other minor compounds not found in total oil such as norisoprenoides, alk-1-enes or chromolaenin. The essential oil showed antimicrobial potential on Escherichia coli, Salmonella enteritidis, Staphylococcus aureus and Bacillus cereus. On the other hand, no antibacterial activity of the oil was observed on Pseudomonas fluorescens and Lysteria monocytogenes. Full article
Open AccessArticle The Role of Water in Lanthanide-Catalyzed Carbon–Carbon Bond Formation
Molecules 2012, 17(2), 2073-2081; doi:10.3390/molecules17022073
Received: 26 January 2012 / Revised: 10 February 2012 / Accepted: 14 February 2012 / Published: 20 February 2012
Cited by 10 | PDF Full-text (258 KB)
Abstract
Luminescence-decay measurements in combination with high-performance liquid chromatography analyses were used to study the relationship between rates of catalysis and water-coordination numbers of europium-based precatalysts in the aqueous Mukaiyama aldol reaction. A correlation between reactivity and water-coordination number was observed and is [...] Read more.
Luminescence-decay measurements in combination with high-performance liquid chromatography analyses were used to study the relationship between rates of catalysis and water-coordination numbers of europium-based precatalysts in the aqueous Mukaiyama aldol reaction. A correlation between reactivity and water-coordination number was observed and is reported here. Full article
(This article belongs to the Special Issue Reactions in Water)
Open AccessArticle Regulated Expressions of MMP-2, -9 by Diterpenoids from Euphorbia formosana Hayata
Molecules 2012, 17(2), 2082-2090; doi:10.3390/molecules17022082
Received: 29 November 2011 / Revised: 3 February 2012 / Accepted: 6 February 2012 / Published: 21 February 2012
Cited by 3 | PDF Full-text (421 KB)
Abstract
Two new abietane type diterpenoids, namely seco-helioscopinolide (1) and 3b,7b-dihydroxy-ent-abieta-8,13-diene-12,16-olide (2) were isolated from the aerial parts of Euphorbia formosana Hayata together with helioscopinolide A (3), helioscopinolide B (4), helioscopinolide C [...] Read more.
Two new abietane type diterpenoids, namely seco-helioscopinolide (1) and 3b,7b-dihydroxy-ent-abieta-8,13-diene-12,16-olide (2) were isolated from the aerial parts of Euphorbia formosana Hayata together with helioscopinolide A (3), helioscopinolide B (4), helioscopinolide C (5) and ent-(5b,8a,9b,10a,12a)-12-hydroxyatis-16-ene-3,14-dione (6). The structures of compounds 16 were elucidated by analyzing their spectroscopic data and comparison with the literature. Further biological tests by gelatin zymographic analysis revealed that 35 significantly up-regulated the expressions and activation of MMP-2 and -9 in human fibrosarcoma cell line HT1080. Full article
Open AccessCommunication Total Synthesis of Flocoumafen via Knoevenagel Condensation and Intramolecular Ring Cyclization: General Access to Natural Products
Molecules 2012, 17(2), 2091-2102; doi:10.3390/molecules17022091
Received: 4 January 2012 / Revised: 9 February 2012 / Accepted: 14 February 2012 / Published: 21 February 2012
Cited by 3 | PDF Full-text (316 KB) | Supplementary Files
Abstract
The total synthesis and structure determination of cis- and trans-flocoumafen was described. The key synthetic steps involve Knoevenagel condensation with p-methoxybenzaldehyde, in situ decarboxylation and intramolecular ring cyclization to construct the tetralone skeleton. Stereospecific reduction of the O-alkylated ketone [...] Read more.
The total synthesis and structure determination of cis- and trans-flocoumafen was described. The key synthetic steps involve Knoevenagel condensation with p-methoxybenzaldehyde, in situ decarboxylation and intramolecular ring cyclization to construct the tetralone skeleton. Stereospecific reduction of the O-alkylated ketone 13 afforded good yield of precusor alcohol 5. Final coupling of alcohol 5 with 4-hydroxy-coumarin yielded flocoumafen (1). Separation and structure determination of cis- and trans-flocoumafen through 2D NMR analyses-assisted computer simulation techniques for the evaluation of anticoagulant activities are reported for the first time. This method is useful for generating the core tetralone skeleton of 4-hydroxycoumarin derivatives and provides a generalized access to various warfarin type anticoagulants. Full article
(This article belongs to the Section Organic Synthesis)
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Open AccessArticle In Vitro Antibacterial and Time-Kill Assessment of Crude Methanolic Stem Bark Extract of Acacia mearnsii De Wild against Bacteria in Shigellosis
Molecules 2012, 17(2), 2103-2118; doi:10.3390/molecules17022103
Received: 13 January 2012 / Revised: 13 February 2012 / Accepted: 15 February 2012 / Published: 21 February 2012
Cited by 6 | PDF Full-text (325 KB)
Abstract
Shigellosis is an important cause of worldwide morbidity and mortality among young children and old people for which treatment with antimicrobial agents is limited. Hence, the need for curative potentials obtainable from medicinal plants becomes inevitable. This study was carried out to [...] Read more.
Shigellosis is an important cause of worldwide morbidity and mortality among young children and old people for which treatment with antimicrobial agents is limited. Hence, the need for curative potentials obtainable from medicinal plants becomes inevitable. This study was carried out to assess the antibacterial potentials of crude methanolic extract of the stem bark of Acacia mearnsii against some selected bacteria of clinical importance in shigellosis. The bacteria were inhibited by the extract to produce concentration dependent inhibition zones. The extract exhibited a varied degree of antibacterial activity against all the tested isolates. The MIC values for Gram negative (0.0391–0.3125) mg/mL and those of Gram positive bacteria (0.0781–0.625) mg/mL indicated that the Gram negative bacteria were more inhibited by the extract than the Gram positive bacteria. Average log reduction in viable cell count in time-kill assay ranged between −2.456 Log10 to 2.230 Log10 cfu/mL after 4 h of interaction, and between −2.921 Log10 and 1.447 Log10 cfu/mL after 8 h interaction in 1× MIC and 2× MIC of the extract. The study provided scientific justification for the use of the crude methanolic extract from the stem bark of A. mearnsii in shigellosis. The degree of the antibacterial activity indicated that the crude extract is a potential source of bioactive compounds that could be useful for the development of new antimicrobial agents capable of decreasing the burden of drug resistance and cost of management of diseases of clinical and public health importance in South Africa. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle A New Bromoallene-Producing Chemical Type of the Red Alga Laurencia nangii Masuda
Molecules 2012, 17(2), 2119-2125; doi:10.3390/molecules17022119
Received: 27 December 2011 / Revised: 8 February 2012 / Accepted: 13 February 2012 / Published: 21 February 2012
Cited by 11 | PDF Full-text (266 KB) | Supplementary Files
Abstract
Six populations of Laurencia nangii were found to produce three bromoallenes; dihydroitomanallene B (1), itomanallene B (2) and pannosallene (3). Prior to this report, L. nangii were only known to produce C15-acetogenins with acetylene [...] Read more.
Six populations of Laurencia nangii were found to produce three bromoallenes; dihydroitomanallene B (1), itomanallene B (2) and pannosallene (3). Prior to this report, L. nangii were only known to produce C15-acetogenins with acetylene functionality. This could be regarded as a new chemical race of L. nangii. The compound structures were elucidated on the basis of spectroscopic analysis and comparison with those previously reported in literature. Compound 1, dihydroitomanallene B, was isolated as a new compound representing a minor variation of itomanallene B (2). Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Struvite Precipitation for Ammonia Nitrogen Removal in 7-Aminocephalosporanic Acid Wastewater
Molecules 2012, 17(2), 2126-2139; doi:10.3390/molecules17022126
Received: 4 January 2012 / Revised: 14 February 2012 / Accepted: 15 February 2012 / Published: 21 February 2012
Cited by 5 | PDF Full-text (483 KB)
Abstract
7-Aminocephalosporanic acid wastewater usually contains high concentrations of ammonium (NH4+-N), which is known to inhibit nitrification during biological treatment processes. Chemical precipitation is a useful technology to remove ammonium from wastewater. In this paper, the removal of ammonium from [...] Read more.
7-Aminocephalosporanic acid wastewater usually contains high concentrations of ammonium (NH4+-N), which is known to inhibit nitrification during biological treatment processes. Chemical precipitation is a useful technology to remove ammonium from wastewater. In this paper, the removal of ammonium from 7-aminocephalosporanic acid wastewater was studied. The optimum pH, molar ratio, and various chemical compositions of magnesium ammonium phosphate (MAP) precipitation were investigated. The results indicated that ammonium in 7-aminocephalosporanic acid wastewater could be removed at an optimum pH of 9. The Mg2+:NH4+-N:PO43-P molar ratio was readily controlled at a ratio of 1:1:1.1 to both effectively remove ammonium and avoid creating a higher concentration of PO43-P in the effluent. MgCl2·6H2O + 85% H3PO4 was the most efficient combination for NH4+-N removal. Furthermore, the lowest concentration of the residual PO43−-P was obtained with the same combination. Struvite precipitation could be considered an effective technology for the NH4+-N removal from the 7-aminocephalosporanic acid wastewater. Full article
(This article belongs to the Section Medicinal Chemistry)
Open AccessArticle Contribution of Cation-π Interactions in Iminium Catalysis
Molecules 2012, 17(2), 2161-2168; doi:10.3390/molecules17022161
Received: 12 January 2012 / Revised: 9 February 2012 / Accepted: 15 February 2012 / Published: 21 February 2012
Cited by 11 | PDF Full-text (281 KB) | Supplementary Files
Abstract
Ab initio calculations were carried out for a benzyl-substituted iminium cation derived from (E)-crotonaldehyde and a chiral imidazolidinone that was developed as an organocatalyst by MacMillan et al. At the MP2 level of theory it is predicted that the phenyl [...] Read more.
Ab initio calculations were carried out for a benzyl-substituted iminium cation derived from (E)-crotonaldehyde and a chiral imidazolidinone that was developed as an organocatalyst by MacMillan et al. At the MP2 level of theory it is predicted that the phenyl group is close to the iminium moiety in the most stable conformer, suggesting that the cation-π interaction contributes to the stabilization of this conformer. Energy decomposition analyses on model systems indicate that the electrostatic and polarization terms make significant contribution to the attractive interactions between the benzene ring and the iminium cation. Full article
(This article belongs to the Special Issue Organocatalysis)
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Open AccessArticle Effects of Botulinum Toxin Type A on Collagen Deposition in Hypertrophic Scars
Molecules 2012, 17(2), 2169-2177; doi:10.3390/molecules17022169
Received: 16 December 2011 / Revised: 14 February 2012 / Accepted: 17 February 2012 / Published: 21 February 2012
Cited by 14 | PDF Full-text (304 KB)
Abstract
A recent study reported that Botulinum toxin type A (BTXA) could inhibit the growth of hypertrophic scars and improve their appearance. However, the mechanism of BTXA’s action on hypertrophic scars is still unknown. Some in vitro studies had shown BTXA could alleviate hypertrophic scars by acting on the biological behavior of fibroblasts, but there are few in vivo experiments, especially animal model experiments, supporting these findings. The aim of the study reported herein was to investigate the effect of BTXA on collagen deposition on hypertrophic scars in a rabbit ear model and partially clarify the mechanism of BTXA on the hypertrophy of scars. The rabbit hypertrophic scar model was used and eight rabbits were employed. BTXA was injected into the hypertrophic scar tissue of one ear; and the other ear in the same rabbit was the control without BTXA injection. The scar thickness and deposition of collagen was examined through immune histochemistry including haematoxylin and eosin (H&E) and Masson trichrome staining. The thicknesses of hypertrophic scars in the BTXA treatment group were obviously lower than in the control groups (P < 0.01). H&E and Masson staining showed that collagen fibers were stained blue. Compared with the treatment group, the collagen fibers were thicker and the arrangement of collagen fibers were disordered in the control group. This study used the rabbit ear model of hypertrophic scars to assess the effects of BTXA on scar hypertrophy. The application of BTXA may be useful for inhibiting hypertrophic scars. Full article
Open AccessCommunication A Comparative Study of Nozzle/Diffuser Micropumps with Novel Valves
Molecules 2012, 17(2), 2178-2187; doi:10.3390/molecules17022178
Received: 16 December 2011 / Revised: 16 February 2012 / Accepted: 17 February 2012 / Published: 22 February 2012
Cited by 7 | PDF Full-text (550 KB)
Abstract
This study conducts an experimental study concerning the improvement of nozzle/diffuser micropump design using some novel no-moving-part valves. A total of three micropumps, including two enhancement structures having two-fin or obstacle structure and one conventional micro nozzle/diffuser design, are made and tested [...] Read more.
This study conducts an experimental study concerning the improvement of nozzle/diffuser micropump design using some novel no-moving-part valves. A total of three micropumps, including two enhancement structures having two-fin or obstacle structure and one conventional micro nozzle/diffuser design, are made and tested in this study. It is found that dramatic increase of the pressure drops across the designed micro nozzles/diffusers are seen when the obstacle or fin structure is added. The resultant maximum flow rates are 47.07 mm3/s and 53.39 mm3/s, respectively, for the conventional micro nozzle/diffuser and the added two-fin structure in micro nozzle/diffuser operated at a frequency of 400 Hz. Yet the mass flow rate for two-fin design surpasses that of conventional one when the frequency is below 425 Hz but the trend is reversed with a further increase of frequency. This is because the maximum efficiency ratio improvement for added two-fin is appreciably higher than the other design at a lower operating frequency. In the meantime, despite the efficiency ratio of the obstacle structure also reveals a similar trend as that of two-fin design, its significant pressure drop (flow resistance) had offset its superiority at low operating frequency, thereby leading to a lesser flow rate throughout the test range. Full article
(This article belongs to the Special Issue Flow Chemistry)
Open AccessArticle Benefits of Combinations of Vitamin A, C and E Derivatives in the Stability of Cosmetic Formulations
Molecules 2012, 17(2), 2219-2230; doi:10.3390/molecules17022219
Received: 19 December 2011 / Revised: 1 February 2012 / Accepted: 16 February 2012 / Published: 22 February 2012
Cited by 12 | PDF Full-text (294 KB)
Abstract
Chemically stable ester derivatives of vitamins A, C and E have become a focus of interest for their role in the satisfactory results in skin aging treatments. Accordingly, the aim of this study was to evaluate the physical and chemical stability of [...] Read more.
Chemically stable ester derivatives of vitamins A, C and E have become a focus of interest for their role in the satisfactory results in skin aging treatments. Accordingly, the aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing 1% retinyl palmitate, ascorbyl tetraisopalmitate and tocopheryl acetate, alone or in combination. In the studies of physical stability, a Brookfield rheometer was used to determine rheological behavior of formulations containing the vitamins. Chemical stability was determined by HPLC on a Shimadzu system with UV detection. Results showed that formulations had pseudoplastic behavior and that vitamins did not alter their apparent viscosity and thixotropy. In the chemical stability studies, first-order reaction equations were used for determinations of the shelf-life of vitamins derivatives considering a remaining concentration of 85%. Combined vitamins in a single formulation had a slightly lower degradation rate as compared to different preparations containing only one of the vitamins. Considering that many cosmetic formulations contain vitamin combinations it is suggested that the present study may contribute to the development of more stable formulations containing liposoluble vitamins. Full article
Open AccessCommunication Preparation and Physical Properties of Chitosan Benzoic Acid Derivatives Using a Phosphoryl Mixed Anhydride System
Molecules 2012, 17(2), 2231-2239; doi:10.3390/molecules17022231
Received: 1 January 2012 / Revised: 15 February 2012 / Accepted: 16 February 2012 / Published: 22 February 2012
Cited by 3 | PDF Full-text (358 KB)
Abstract
Direct benzoylation of the two hydroxyl groups on chitosan was achieved using a phosphoryl mixed anhydride system, derived from trifluoroacetic anhydride (TFAA), benzoic acids (BAs), and phosphoric acid (PA). The reaction is operated as a one pot process under mild conditions that [...] Read more.
Direct benzoylation of the two hydroxyl groups on chitosan was achieved using a phosphoryl mixed anhydride system, derived from trifluoroacetic anhydride (TFAA), benzoic acids (BAs), and phosphoric acid (PA). The reaction is operated as a one pot process under mild conditions that does not require neither an inert atmosphere nor dry solvents. The structures of the synthesized compounds were confirmed by NMR and IR spectroscopy. Solubility tests on the products revealed that they were soluble in organic solvents such as N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), and acetone. In the meantime, a morphological study by scanning electron microscopy (SEM) evidently indicated that the chitosan benzoates underwent significant structural changes after the benzoylation. Full article
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Open AccessCommunication 2,3,5,4′- Tetrahydroxystilbene-2-O-β-D-glycoside Biosynthesis by Suspension Cells Cultures of Polygonum multiflorum Thunb and Production Enhancement by Methyl Jasmonate and Salicylic Acid
Molecules 2012, 17(2), 2240-2247; doi:10.3390/molecules17022240
Received: 9 January 2012 / Revised: 9 February 2012 / Accepted: 13 February 2012 / Published: 22 February 2012
Cited by 5 | PDF Full-text (279 KB)
Abstract
Friable calli of Polygonum multiflorum Thunb have been induced in MS medium supplemented with 6-benzylaminopurine (6-BA) and kinetin (KT). Suspension cultures were initiated from friable calli by inoculating calli in liquid MS medium in shake flasks in the dark and 25 °C [...] Read more.
Friable calli of Polygonum multiflorum Thunb have been induced in MS medium supplemented with 6-benzylaminopurine (6-BA) and kinetin (KT). Suspension cultures were initiated from friable calli by inoculating calli in liquid MS medium in shake flasks in the dark and 25 °C on an orbital shaker at 100 rpm. The maximum dry weight (DW, 7.85 g/L) and 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glycoside (THSG, 56.39 mg/L) of suspension cells was obtained in MS medium after 16 days culture. Both methyl jasmonate (MeJA) and salicylic acid (SA) could increase THSG production. The most appropriate concentration of MeJA was 100 μmol/L in MS medium, in which concentration THSG content reached the maximum value of 147.79 mg/L, which represented a 162.36% increase compared to that of the control (56.33 mg/L). The most appropriate concentration of SA was 125 μmol/L in MS medium, at which concentration THSG content reached its maximum value of 116.43 mg/L, a 106.69% increase compared to that of the control (56.33 mg/L). Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Synthesis and Biological Evaluation of 2-(3-Fluoro-4-nitro phenoxy)-N-phenylacetamide Derivatives as Novel Potential Affordable Antitubercular Agents
Molecules 2012, 17(2), 2248-2258; doi:10.3390/molecules17022248
Received: 3 February 2012 / Revised: 20 February 2012 / Accepted: 20 February 2012 / Published: 22 February 2012
Cited by 8 | PDF Full-text (285 KB)
Abstract
A novel series of 2-(3-fluoro-4-nitrophenoxy)-N-phenylacetamide compounds were designed, synthesized and in vitro assessed for their antitubercular activities by a microdilution method. All the novel derivatives exerted potent or moderate active against M. tuberculosis H37Rv, with MIC values ranging [...] Read more.
A novel series of 2-(3-fluoro-4-nitrophenoxy)-N-phenylacetamide compounds were designed, synthesized and in vitro assessed for their antitubercular activities by a microdilution method. All the novel derivatives exerted potent or moderate active against M. tuberculosis H37Rv, with MIC values ranging from 4 to 64 μg/mL. The most potent derivative 3m showed an identical MIC value of 4 μg/mL for both M. tuberculosis H37Rv and rifampin-resistant M. tuberculosis 261. It demonstrated no inhibitory effects against six different tumor cell lines by a MTT assay and had a good safety profile in a vero cell line, providing a good lead for subsequent optimization in search of novel affordable antitubercular agents. Full article
(This article belongs to the Section Medicinal Chemistry)
Open AccessArticle Structure-Odor Relationships of α­Santalol Derivatives with Modified Side Chains
Molecules 2012, 17(2), 2259-2270; doi:10.3390/molecules17022259
Received: 20 December 2011 / Revised: 16 February 2012 / Accepted: 20 February 2012 / Published: 22 February 2012
Cited by 5 | PDF Full-text (503 KB) | Correction | Supplementary Files
Abstract
(Z)-α-Santalol, which has a unique woody odor, is a main constituent of sandalwood essential oil. We investigated the structure-odor relationship of (Z)-α-santalol and its derivatives, focusing on the relationship between the structure of the side chain and the [...] Read more.
(Z)-α-Santalol, which has a unique woody odor, is a main constituent of sandalwood essential oil. We investigated the structure-odor relationship of (Z)-α-santalol and its derivatives, focusing on the relationship between the structure of the side chain and the odor of the compounds. Various α-santalol derivatives (aldehydes, formates, and acetates) were synthesized from (Z)- and (E)-α-santalol, which were prepared from (+)-3-bromocamphor through modifications of a reported synthetic route. The Z- and E-isomers of α-santalols have different double-bond configurations in the side chain. Analogues with saturated side chains were also prepared from the corresponding α-santalols, and the odors of the all the prepared compounds were evaluated. We found that the odors of the Z-isomers (woody) were similar to those of the corresponding saturated compounds, but clearly different from the odors of the corresponding E-isomers (odorless, fresh, or fatty). These results indicate that the relative configuration of the side chain with respect to the santalane frame plays an important role in the odor of α-santalol. E-configuration in the side chain eliminates the woody odor character of α-santalol and its examined derivatives, whereas the Z-configuration or saturation of the carbon side chain does not. Full article
(This article belongs to the Special Issue Terpenoids)

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Open AccessReview Chiroptical Switches: Applications in Sensing and Catalysis
Molecules 2012, 17(2), 1247-1277; doi:10.3390/molecules17021247
Received: 28 December 2011 / Revised: 18 January 2012 / Accepted: 20 January 2012 / Published: 31 January 2012
Cited by 26 | PDF Full-text (2616 KB)
Abstract
Chiroptical switches have found application in the detection of a multitude of different analytes with a high level of sensitivity and in asymmetric catalysis to offer switchable stereoselectivity. A wide range of scaffolds have been employed that respond to metals, small molecules, [...] Read more.
Chiroptical switches have found application in the detection of a multitude of different analytes with a high level of sensitivity and in asymmetric catalysis to offer switchable stereoselectivity. A wide range of scaffolds have been employed that respond to metals, small molecules, anions and other analytes. Not only have chiroptical systems been used to detect the presence of analytes, but also other properties such as oxidation state and other physical phenomena that influence helicity and conformation of molecules and materials. Moreover, the tunable responses of many such chiroptical switches enable them to be used in the controlled production of either enantiomer or diastereomer at will in many important organic reactions from a single chiral catalyst through selective use of a low-cost inducer: Co-catalysts (guests), metal ions, counter ions or anions, redox agents or electrochemical potential, solvents, mechanical forces, temperature or electromagnetic radiation. Full article
(This article belongs to the Special Issue Chiroptical Techniques)
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Open AccessReview Supramolecular Photodimerization of Coumarins
Molecules 2012, 17(2), 1408-1418; doi:10.3390/molecules17021408
Received: 10 January 2012 / Revised: 31 January 2012 / Accepted: 1 February 2012 / Published: 3 February 2012
Cited by 13 | PDF Full-text (563 KB)
Abstract Stereoselective photodimerization of coumarin and its derivatives in supra-molecular systems is reviewed. The enantioselective photodimerization of coumarin and thiocoumarin in inclusion crystals with optically active host compounds is also described. Full article
(This article belongs to the Special Issue Coumarins and Xanthones)
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Open AccessReview Communic Acids: Occurrence, Properties and Use as Chirons for the Synthesis of Bioactive Compounds
Molecules 2012, 17(2), 1448-1467; doi:10.3390/molecules17021448
Received: 25 November 2011 / Revised: 31 January 2012 / Accepted: 31 January 2012 / Published: 6 February 2012
Cited by 10 | PDF Full-text (569 KB)
Abstract
Communic acids are diterpenes with labdane skeletons found in many plant species, mainly conifers, predominating in the genus Juniperus (fam. Cupresaceae). In this review we briefly describe their distribution and different biological activities (anti- bacterial, antitumoral, hypolipidemic, relaxing smooth muscle, etc. [...] Read more.
Communic acids are diterpenes with labdane skeletons found in many plant species, mainly conifers, predominating in the genus Juniperus (fam. Cupresaceae). In this review we briefly describe their distribution and different biological activities (anti- bacterial, antitumoral, hypolipidemic, relaxing smooth muscle, etc.). This paper also includes a detailed explanation of their use as chiral building blocks for the synthesis of bioactive natural products. Among other uses, communic acids have proven useful as chirons for the synthesis of quassinoids (formal), abietane antioxidants, ambrox and other perfume fixatives, podolactone herbicides, etc., featuring shorter and more efficient processes. Full article
(This article belongs to the Special Issue Terpenoids)
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Open AccessReview Anthocyanins and Their Variation in Red Wines II. Anthocyanin Derived Pigments and Their Color Evolution
Molecules 2012, 17(2), 1483-1519; doi:10.3390/molecules17021483
Received: 2 December 2011 / Revised: 25 January 2012 / Accepted: 2 February 2012 / Published: 7 February 2012
Cited by 37 | PDF Full-text (1562 KB)
Abstract
Originating in the grapes, anthocyanins and their derivatives are the crucial pigments responsible for the red wine color. During wine maturation and aging, the concentration of monomeric anthocyanins declines constantly, while numerous more complex and stable anthocyanin derived pigments are formed, mainly [...] Read more.
Originating in the grapes, anthocyanins and their derivatives are the crucial pigments responsible for the red wine color. During wine maturation and aging, the concentration of monomeric anthocyanins declines constantly, while numerous more complex and stable anthocyanin derived pigments are formed, mainly including pyranoanthocyanins, polymeric anthocyanins produced from condensation between anthocyanin and/or flavan-3-ols directly or mediated by aldehydes. Correspondingly, their structural modifications result in a characteristic variation of color, from purple-red color in young red wines to brick-red hue of the aged. Because of the extreme complexity of chemical compounds involved, many investigations have been made using model solutions of know composition rather than wine. Thus, there is a large amount of research still required to obtain an overall perspective of the anthocyanin composition and its change with time in red wines. Future findings may well greatly revise our current interpretation of the color in red wines. This paper summarizes the most recent advances in the studies of the anthocyanins derived pigments in red wines, as well as their color evolution. Full article
Open AccessReview Benzoxetes and Benzothietes ¾ Heterocyclic Analogues of Benzocyclobutene
Molecules 2012, 17(2), 1548-1570; doi:10.3390/molecules17021548
Received: 7 December 2011 / Revised: 13 January 2012 / Accepted: 17 January 2012 / Published: 7 February 2012
Cited by 7 | PDF Full-text (902 KB)
Abstract
Benzo-condensed four-ring heterocycles, such as benzoxetes 1 and benzothietes 3 represent multi-purpose starting compounds for the preparation of various higher heterocyclic ring systems. The thermal or photochemical valence isomerizations between the benzenoid forms 1,3 and the higher reactive o-quinoid [...] Read more.
Benzo-condensed four-ring heterocycles, such as benzoxetes 1 and benzothietes 3 represent multi-purpose starting compounds for the preparation of various higher heterocyclic ring systems. The thermal or photochemical valence isomerizations between the benzenoid forms 1,3 and the higher reactive o-quinoid structures 2,4 provide the basis for the synthetic applications. On the other hand, this valence isomerization impedes in particular the generation and storage of 1 because the thermal equilibrium 1 2 is completely on the side of 2. Thus, the number of erroneous or questionable benzoxete structures published to date is surprisingly high. On the contrary, the thermal equilibrium 3 4 is on the side of the benzothietes 3, which makes them easily accessible, especially by different flash vacuum pyrolysis techniques. The present article gives a survey of the preparations of 1 and 2, and tries to stimulate their use in synthetic projects. Naphtho-condensed and higher condensed compounds and compounds with an exocyclic C=O or S=O double bond (lactones, thiolactones, sulfoxides and sulfones) are not covered in this article. Full article
(This article belongs to the Special Issue Heterocycles)
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Open AccessReview Anthocyanins and Their Variation in Red Wines I. Monomeric Anthocyanins and Their Color Expression
Molecules 2012, 17(2), 1571-1601; doi:10.3390/molecules17021571
Received: 2 December 2011 / Revised: 24 January 2012 / Accepted: 2 February 2012 / Published: 7 February 2012
Cited by 54 | PDF Full-text (680 KB)
Abstract
Originating in the grapes, monomeric anthocyanins in young red wines contribute the majority of color and the supposed beneficial health effects related to their consumption, and as such they are recognized as one of the most important groups of phenolic metabolites in [...] Read more.
Originating in the grapes, monomeric anthocyanins in young red wines contribute the majority of color and the supposed beneficial health effects related to their consumption, and as such they are recognized as one of the most important groups of phenolic metabolites in red wines. In recent years, our increasing knowledge of the chemical complexity of the monomeric anthocyanins, their stability, together with the phenomena such as self-association and copigmentation that can stabilize and enhance their color has helped to explain their color representation in red wine making and aging. A series of new enological practices were developed to improve the anthocyanin extraction, as well as their color expression and maintenance. This paper summarizes the most recent advances in the studies of the monomeric anthocyanins in red wines, emphasizing their origin, occurrence, color enhancing effects, their degradation and the effect of various enological practices on them. Full article
Open AccessReview Applications of Supercritical Fluid Extraction (SFE) of Palm Oil and Oil from Natural Sources
Molecules 2012, 17(2), 1764-1794; doi:10.3390/molecules17021764
Received: 24 December 2011 / Revised: 8 February 2012 / Accepted: 9 February 2012 / Published: 10 February 2012
Cited by 16 | PDF Full-text (369 KB)
Abstract
Supercritical fluid extraction (SFE), which has received much interest in its use and further development for industrial applications, is a method that offers some advantages over conventional methods, especially for the palm oil industry. SC-CO2 refers to supercritical fluid extraction (SFE) [...] Read more.
Supercritical fluid extraction (SFE), which has received much interest in its use and further development for industrial applications, is a method that offers some advantages over conventional methods, especially for the palm oil industry. SC-CO2 refers to supercritical fluid extraction (SFE) that uses carbon dioxide (CO2) as a solvent which is a nontoxic, inexpensive, nonflammable, and nonpolluting supercritical fluid solvent for the extraction of natural products. Almost 100% oil can be extracted and it is regarded as safe, with organic solvent-free extracts having superior organoleptic profiles. The palm oil industry is one of the major industries in Malaysia that provides a major contribution to the national income. Malaysia is the second largest palm oil and palm kernel oil producer in the World. This paper reviews advances in applications of supercritical carbon dioxide (SC-CO2) extraction of oils from natural sources, in particular palm oil, minor constituents in palm oil, producing fractionated, refined, bleached, and deodorized palm oil, palm kernel oil and purified fatty acid fractions commendable for downstream uses as in toiletries and confectionaries. Full article
Open AccessReview Fructose Might Contribute to the Hypoglycemic Effect of Honey
Molecules 2012, 17(2), 1900-1915; doi:10.3390/molecules17021900
Received: 31 January 2012 / Revised: 9 February 2012 / Accepted: 9 February 2012 / Published: 15 February 2012
Cited by 19 | PDF Full-text (190 KB)
Abstract
Honey is a natural substance with many medicinal properties, including antibacterial, hepatoprotective, hypoglycemic, antioxidant and antihypertensive effects. It reduces hyperglycemia in diabetic rats and humans. However, the mechanism(s) of its hypoglycemic effect remain(s) unknown. Honey comprises many constituents, making it difficult to [...] Read more.
Honey is a natural substance with many medicinal properties, including antibacterial, hepatoprotective, hypoglycemic, antioxidant and antihypertensive effects. It reduces hyperglycemia in diabetic rats and humans. However, the mechanism(s) of its hypoglycemic effect remain(s) unknown. Honey comprises many constituents, making it difficult to ascertain which component(s) contribute(s) to its hypoglycemic effect. Nevertheless, available evidence indicates that honey consists of predominantly fructose and glucose. The objective of this review is to summarize findings which indicate that fructose exerts a hypoglycemic effect. The data show that glucose and fructose exert a synergistic effect in the gastrointestinal tract and pancreas. This synergistic effect might enhance intestinal fructose absorption and/or stimulate insulin secretion. The results indicate that fructose enhances hepatic glucose uptake and glycogen synthesis and storage via activation of hepatic glucokinase and glycogen synthase, respectively. The data also demonstrate the beneficial effects of fructose on glycemic control, glucose- and appetite-regulating hormones, body weight, food intake, oxidation of carbohydrate and energy expenditure. In view of the similarities of these effects of fructose with those of honey, the evidence may support the role of fructose in honey in mediating the hypoglycemic effect of honey. Full article
Open AccessReview The Use of Stable and Radioactive Sterol Tracers as a Tool to Investigate Cholesterol Degradation to Bile Acids in Humans in Vivo
Molecules 2012, 17(2), 1939-1968; doi:10.3390/molecules17021939
Received: 13 January 2012 / Revised: 3 February 2012 / Accepted: 8 February 2012 / Published: 16 February 2012
Cited by 2 | PDF Full-text (328 KB)
Abstract
Alterations of cholesterol homeostasis represent important risk factors for atherosclerosis and cardiovascular disease. Different clinical-experimental approaches have been devised to study the metabolism of cholesterol and particularly the synthesis of bile acids, its main catabolic products. Most evidence in humans has derived [...] Read more.
Alterations of cholesterol homeostasis represent important risk factors for atherosclerosis and cardiovascular disease. Different clinical-experimental approaches have been devised to study the metabolism of cholesterol and particularly the synthesis of bile acids, its main catabolic products. Most evidence in humans has derived from studies utilizing the administration of labeled sterols; these have several advantages over in vitro assay of enzyme activity and expression, requiring an invasive procedure such as a liver biopsy, or the determination of fecal sterols, which is cumbersome and not commonly available. Pioneering evidence with administration of radioactive sterol derivatives has allowed to characterize the alterations of cholesterol metabolism and degradation in different situations, including spontaneous disease conditions, aging, and drug treatment. Along with the classical isotope dilution methodology, other approaches were proposed, among which isotope release following radioactive substrate administration. More recently, stable isotope studies have allowed to overcome radioactivity exposure. Isotope enrichment studies during tracer infusion has allowed to characterize changes in the degradation of cholesterol via the “classical” and the “alternative” pathways of bile acid synthesis. Evidence brought by tracer studies in vivo, summarized here, provides an exceptional tool for the investigation of sterol metabolism, and integrate the studies in vitro on human tissue. Full article
(This article belongs to the Special Issue Steroids)
Open AccessReview Astaxanthin in Cardiovascular Health and Disease
Molecules 2012, 17(2), 2030-2048; doi:10.3390/molecules17022030
Received: 18 January 2012 / Revised: 13 February 2012 / Accepted: 13 February 2012 / Published: 20 February 2012
Cited by 29 | PDF Full-text (289 KB)
Abstract
Oxidative stress and inflammation are established processes contributing to cardiovascular disease caused by atherosclerosis. However, antioxidant therapies tested in cardiovascular disease such as vitamin E, C and β-carotene have proved unsuccessful at reducing cardiovascular events and mortality. Although these outcomes may reflect [...] Read more.
Oxidative stress and inflammation are established processes contributing to cardiovascular disease caused by atherosclerosis. However, antioxidant therapies tested in cardiovascular disease such as vitamin E, C and β-carotene have proved unsuccessful at reducing cardiovascular events and mortality. Although these outcomes may reflect limitations in trial design, new, more potent antioxidant therapies are being pursued. Astaxanthin, a carotenoid found in microalgae, fungi, complex plants, seafood, flamingos and quail is one such agent. It has antioxidant and anti-inflammatory effects. Limited, short duration and small sample size studies have assessed the effects of astaxanthin on oxidative stress and inflammation biomarkers and have investigated bioavailability and safety. So far no significant adverse events have been observed and biomarkers of oxidative stress and inflammation are attenuated with astaxanthin supplementation. Experimental investigations in a range of species using a cardiac ischaemia-reperfusion model demonstrated cardiac muscle preservation when astaxanthin is administered either orally or intravenously prior to the induction of ischaemia. Human clinical cardiovascular studies using astaxanthin therapy have not yet been reported. On the basis of the promising results of experimental cardiovascular studies and the physicochemical and antioxidant properties and safety profile of astaxanthin, clinical trials should be undertaken. Full article
(This article belongs to the Special Issue Carotenoids)
Open AccessReview Reaction Dynamics of Flavonoids and Carotenoids as Antioxidants
Molecules 2012, 17(2), 2140-2160; doi:10.3390/molecules17022140
Received: 4 January 2012 / Revised: 30 January 2012 / Accepted: 3 February 2012 / Published: 21 February 2012
Cited by 29 | PDF Full-text (410 KB)
Abstract
Flavonoids and carotenoids with rich structural diversity are ubiquitously present in the plant kingdom. Flavonoids, and especially their glycosides, are more hydrophilic than most carotenoids. The interaction of flavonoids with carotenoids occurs accordingly at water/lipid interfaces and has been found important for [...] Read more.
Flavonoids and carotenoids with rich structural diversity are ubiquitously present in the plant kingdom. Flavonoids, and especially their glycosides, are more hydrophilic than most carotenoids. The interaction of flavonoids with carotenoids occurs accordingly at water/lipid interfaces and has been found important for the functions of flavonoids as antioxidants in the water phase and especially for the function of carotenoids as antioxidants in the lipid phase. Based on real-time kinetic methods for the fast reactions between (iso)flavonoids and radicals of carotenoids, antioxidant synergism during protection of unsaturated lipids has been found to depend on: (i) the appropriate distribution of (iso)flavonoids at water/lipid interface, (ii) the difference between the oxidation potentials of (iso)flavonoid and carotenoid and, (iii) the presence of electron-withdrawing groups in the carotenoid for facile electron transfer. For some (unfavorable) combinations of (iso)flavonoids and carotenoids, antioxidant synergism is replaced by antagonism, despite large potential differences. For contact with the lipid phase, the lipid/water partition coefficient is of importance as a macroscopic property for the flavonoids, while intramolecular rotation towards coplanarity upon oxidation by the carotenoid radical cation has been identified by quantum mechanical calculations to be an important microscopic property. For carotenoids, anchoring in water/lipid interface by hydrophilic groups allow the carotenoids to serve as molecular wiring across membranes for electron transport. Full article
(This article belongs to the Special Issue Carotenoids)
Open AccessReview Mechanisms of Suppression and Enhancement of Photocurrent/Conversion Efficiency in Dye-Sensitized Solar-Cells Using Carotenoid and Chlorophyll Derivatives as Sensitizers
Molecules 2012, 17(2), 2188-2218; doi:10.3390/molecules17022188
Received: 10 December 2011 / Revised: 14 February 2012 / Accepted: 15 February 2012 / Published: 22 February 2012
Cited by 8 | PDF Full-text (2252 KB)
Abstract
The mechanisms of suppression and enhancement of photocurrent/conversion efficiency (performance) in dye-sensitized solar cells, using carotenoid and chlorophyll derivatives as sensitizers, were compared systematically. The key factor to enhance the performance was found to be how to minimize interaction among the excited-state [...] Read more.
The mechanisms of suppression and enhancement of photocurrent/conversion efficiency (performance) in dye-sensitized solar cells, using carotenoid and chlorophyll derivatives as sensitizers, were compared systematically. The key factor to enhance the performance was found to be how to minimize interaction among the excited-state dye-sensitizer(s). In a set of retinoic-acid (RA) and carotenoic-acid (CA) sensitizers, having n conjugated double bonds, CA7 gave rise to the highest performance, which was reduced toward RA5 and CA13. The former was ascribed to the generation of triplet and the resultant singlet-triplet annihilation reaction, while the latter, to the intrinsic electron injection efficiency. In a set of shorter polyene sensitizers having different polarizabilities, the one with the highest polarizability (the highest trend of aggregate formation) exhibited the higher performance toward the lower dye concentration and the lower light intensity, contrary to our expectation. This is ascribed to a decrease in the singlet-triplet annihilation reaction. The performance of cosensitization, by a pair of pheophorbide sensitizers without and with the central metal, Mg or Zn, was enhanced by the light absorption (complementary rather than competitive), the transition-dipole moments (orthogonal rather than parallel) and by the pathways of electron injection (energetically independent rather than interactive). Full article
(This article belongs to the Special Issue Carotenoids)

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