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Molecules, Volume 18, Issue 4 (April 2013), Pages 3641-4843

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Open AccessArticle Theoretical Analysis on the Kinetic Isotope Effects of Bimolecular Nucleophilic Substitution (SN2) Reactions and Their Temperature Dependence
Molecules 2013, 18(4), 4816-4843; https://doi.org/10.3390/molecules18044816
Received: 13 March 2013 / Revised: 3 April 2013 / Accepted: 18 April 2013 / Published: 23 April 2013
Cited by 7 | Viewed by 3252 | PDF Full-text (458 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Factors affecting the kinetic isotope effects (KIEs) of the gas-phase SN2 reactions and their temperature dependence have been analyzed using the ion-molecule collision theory and the transition state theory (TST). The quantum-mechanical tunneling effects were also considered using the canonical variational
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Factors affecting the kinetic isotope effects (KIEs) of the gas-phase SN2 reactions and their temperature dependence have been analyzed using the ion-molecule collision theory and the transition state theory (TST). The quantum-mechanical tunneling effects were also considered using the canonical variational theory with small curvature tunneling (CVT/SCT). We have benchmarked a few ab initio and density functional theory (DFT) methods for their performance in predicting the deuterium KIEs against eleven experimental values. The results showed that the MP2/aug-cc-pVDZ method gave the most accurate prediction overall. The slight inverse deuterium KIEs usually observed for the gas-phase SN2 reactions at room temperature were due to the balance of the normal rotational contribution and the significant inverse vibrational contribution. Since the vibrational contribution is a sensitive function of temperature while the rotation contribution is temperature independent, the KIEs are thus also temperature dependent. For SN2 reactions with appreciable barrier heights, the tunneling effects were predicted to contribute significantly both to the rate constants and to the carbon-13, and carbon-14 KIEs, which suggested important carbon atom tunneling at and below room temperature. Full article
(This article belongs to the Special Issue Isotope Effects)
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Open AccessArticle Intravenous and Subcutaneous Toxicity and Absorption Kinetics in Mice and Dogs of the Antileishmanial Triterpene Saponin PX-6518
Molecules 2013, 18(4), 4803-4815; https://doi.org/10.3390/molecules18044803
Received: 16 February 2013 / Revised: 7 April 2013 / Accepted: 19 April 2013 / Published: 22 April 2013
Cited by 2 | Viewed by 2784 | PDF Full-text (939 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The intravenous (IV) and subcutaneous (SC) toxicity and absorption kinetics of the antileishmanial triterpene saponin PX-6518 and its active constituents maesabalide-III and -IV were studied in mice and dogs. A high-dose wash-out study of PX-6518 at 20 mg/kg SC for 5 days and
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The intravenous (IV) and subcutaneous (SC) toxicity and absorption kinetics of the antileishmanial triterpene saponin PX-6518 and its active constituents maesabalide-III and -IV were studied in mice and dogs. A high-dose wash-out study of PX-6518 at 20 mg/kg SC for 5 days and a single low-dose wash-out study at 1, 2.5 or 5 mg/kg SC and IV with follow-up until day 35 after treatment were performed in mice. Beagle dogs received three escalating doses of maesabalide-III and -IV at weekly intervals (0.01, 0.1 and 0.5 mg/kg IV and maesabalide-III was also dosed SC at 0.1, 0.2 and 0.4 mg/kg). Endpoint measurements included clinical, hematological and serum biochemical parameters. Pathology and toxicokinetic studies were performed on the dogs. Whereas the neutrophils and aspartate aminotransferase and alanine aminotransferase levels were increased in the high-dose wash-out mouse study, these parameters did not change in the low-dose wash-out study. The dogs were far more susceptible than mice to liver toxicity (hepatocellular necrosis and elevated liver enzymes) and developed a painful inflammatory reaction at the SC injection site. Toxicokinetic analysis revealed a non dose-linear systemic availability with plasma concentrations above the antileishmanial IC50 after only a single dose at 0.01 mg/kg IV or 0.1 mg/kg SC. Related to the long half-life (T1/2 71–91 h after SC dosing), repeated dosing at weekly intervals may result in drug accumulation and enhanced toxicity. It was decided not to pursue further drug development for PX-6518 because of the hepatotoxic risk. Full article
(This article belongs to the Special Issue Triterpenes and Triterpenoids 2013)
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Open AccessArticle 1H-MAS-NMR Chemical Shifts in Hydrogen-Bonded Complexes of Chlorophenols (Pentachlorophenol, 2,4,6-Trichlorophenol, 2,6-Dichlorophenol, 3,5-Dichlorophenol, and p-Chlorophenol) and Amine, and H/D Isotope Effects on 1H-MAS-NMR Spectra
Molecules 2013, 18(4), 4786-4802; https://doi.org/10.3390/molecules18044786
Received: 1 March 2013 / Revised: 12 April 2013 / Accepted: 18 April 2013 / Published: 22 April 2013
Cited by 5 | Viewed by 3335 | PDF Full-text (564 KB) | HTML Full-text | XML Full-text
Abstract
Chemical shifts (CS) of the 1H nucleus in N···H···O type hydrogen bonds (H-bond) were observed in some complexes between chlorophenols [pentachlorophenol (PCP), 2,4,6-tricholorophenol (TCP), 2,6-dichlorophenol (26DCP), 3,5-dichlorophenol (35DCP), and p-chlorophenol (pCP)] and nitrogen-base (N-Base) by solid-state high-resolution 1H-NMR
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Chemical shifts (CS) of the 1H nucleus in N···H···O type hydrogen bonds (H-bond) were observed in some complexes between chlorophenols [pentachlorophenol (PCP), 2,4,6-tricholorophenol (TCP), 2,6-dichlorophenol (26DCP), 3,5-dichlorophenol (35DCP), and p-chlorophenol (pCP)] and nitrogen-base (N-Base) by solid-state high-resolution 1H-NMR with the magic-angle-spinning (MAS) method. Employing N-Bases with a wide range of pKa values (0.65–10.75), 1H-MAS-NMR CS values of bridging H atoms in H-bonds were obtained as a function of the N-Base’s pKa. The result showed that the CS values were increased with increasing pKa values in a range of DpKa < 0 [DpKa = pKa(N-Base) - pKa(chlorophenols)] and decreased when DpKa > 2: The maximum CS values was recorded in the PCP (pKa = 5.26)–4-methylpyridine (6.03), TCP (6.59)–imidazole (6.99), 26DCP (7.02)–2-amino-4-methylpyridine (7.38), 35DCP (8.04)–4-dimethylaminopyridine (9.61), and pCP (9.47)–4-dimethylaminopyridine (9.61) complexes. The largest CS value of 18.6 ppm was recorded in TCP–imidazole crystals. In addition, H/D isotope effects on 1H-MAS-NMR spectra were observed in PCP–2-amino-3-methylpyridine. Based on the results of CS simulation using a B3LYP/6-311+G** function, it can be explained that a little changes of the N–H length in H-bond contribute to the H/D isotope shift of the 1H-MAS-NMR peaks. Full article
(This article belongs to the Special Issue Isotope Effects)
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Open AccessArticle Computational Modeling of the Size Effects on the Optical Vibrational Modes of H-Terminated Ge Nanostructures
Molecules 2013, 18(4), 4776-4785; https://doi.org/10.3390/molecules18044776
Received: 16 January 2013 / Revised: 16 April 2013 / Accepted: 18 April 2013 / Published: 22 April 2013
Cited by 6 | Viewed by 2853 | PDF Full-text (974 KB) | HTML Full-text | XML Full-text
Abstract
The vibrational dispersion relations of porous germanium (pGe) and germanium nanowires (GeNWs) were calculated using the ab initio density functional perturbation theory with a generalized gradient approximation with norm-conserving pseudopotentials. Both pores and nanowires were modeled using the supercell technique. All of the
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The vibrational dispersion relations of porous germanium (pGe) and germanium nanowires (GeNWs) were calculated using the ab initio density functional perturbation theory with a generalized gradient approximation with norm-conserving pseudopotentials. Both pores and nanowires were modeled using the supercell technique. All of the surface dangling bonds were saturated with hydrogen atoms. To address the difference in the confinement between the pores and the nanowires, we calculated the vibrational density of states of the two materials. The results indicate that there is a slight shift in the highest optical mode of the Ge-Ge vibration interval in all of the nanostructures due to the phonon confinement effects. The GeNWs exhibit a reduced phonon confinement compared with the porous Ge due to the mixed Ge-dihydride vibrational modes around the maximum bulk Ge optical mode of approximately 300 cm−1; however, the general effects of such confinements could still be noticed, such as the shift to lower frequencies of the highest optical mode belonging to the Ge vibrations. Full article
(This article belongs to the Special Issue Computational Chemistry)
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Open AccessArticle Chemical Constituents of the Root of Jasminum giraldii
Molecules 2013, 18(4), 4766-4775; https://doi.org/10.3390/molecules18044766
Received: 1 February 2013 / Revised: 26 March 2013 / Accepted: 12 April 2013 / Published: 22 April 2013
Cited by 12 | Viewed by 2989 | PDF Full-text (264 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two new compounds, ethylconiferin (1) and (−)-lariciresinol 4-(6'''-O-cinnamyl-β-d-glucopyranoside) (2), along with the three known compounds (+)-pinoresinol (3), (+)-cycloolivil (4), nobiletin (5), were isolated from the root of Jasminum girialdii
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Two new compounds, ethylconiferin (1) and (−)-lariciresinol 4-(6'''-O-cinnamyl-β-d-glucopyranoside) (2), along with the three known compounds (+)-pinoresinol (3), (+)-cycloolivil (4), nobiletin (5), were isolated from the root of Jasminum girialdii. All these compounds were isolated for the first time from this source. Their structures were elucidated on the basis of extensive spectroscopic analysis and chemical methods. In addition, the in vitro cytotoxic activity of these compounds was evaluated. The results showed that none of the compounds had any significant inhibitory activities on the proliferation of HCT-116 and SW-620 cells. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessReview Application of the Suzuki-Miyaura Reaction in the Synthesis of Flavonoids
Molecules 2013, 18(4), 4739-4765; https://doi.org/10.3390/molecules18044739
Received: 19 March 2013 / Revised: 10 April 2013 / Accepted: 19 April 2013 / Published: 22 April 2013
Cited by 27 | Viewed by 3818 | PDF Full-text (350 KB) | HTML Full-text | XML Full-text
Abstract
The application of the Suzuki-Miyaura reaction in the synthesis of flavonoids, an important class of natural products, is reviewed. This reaction has not only been employed to provide access to flavonoid nuclei, but has also been applied to the synthesis of dimeric flavonoids
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The application of the Suzuki-Miyaura reaction in the synthesis of flavonoids, an important class of natural products, is reviewed. This reaction has not only been employed to provide access to flavonoid nuclei, but has also been applied to the synthesis of dimeric flavonoids and in the synthesis of libraries of flavonoid derivatives for biological activity studies. The classes of flavonoids that are discussed are the chalcones, flavones, isoflavones, neoflavones, biflavones and derivatives of flavonoids obtained by C-C bond formation via the Suzuki-Miyaura reaction. Full article
(This article belongs to the Special Issue Suzuki Reaction)
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Open AccessArticle A New Vanadium (III) Complex of 2,6-Bis(3,5-diphenylpyrazol-1-ylmethyl)pyridine as a Catalyst for Ethylene Polymerization
Molecules 2013, 18(4), 4728-4738; https://doi.org/10.3390/molecules18044728
Received: 11 March 2013 / Revised: 17 April 2013 / Accepted: 18 April 2013 / Published: 22 April 2013
Cited by 15 | Viewed by 2588 | PDF Full-text (326 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The tridentate ligand 2,6-bis(3,5-diphenylpyrazol-1-ylmethyl)pyridine, abbreviated as 2,6-[(3,5-ph2pz-CH2)2-py], a new pyridine-pyrazole derivative, was prepared from 2,6-bis(bromomethyl)pyridine and 3,5-diphenylpyrazole. The ligand was characterized by means of elemental analyses, ATR-IR, 1H- and 13C-NMR spectroscopy and single crystal X-ray
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The tridentate ligand 2,6-bis(3,5-diphenylpyrazol-1-ylmethyl)pyridine, abbreviated as 2,6-[(3,5-ph2pz-CH2)2-py], a new pyridine-pyrazole derivative, was prepared from 2,6-bis(bromomethyl)pyridine and 3,5-diphenylpyrazole. The ligand was characterized by means of elemental analyses, ATR-IR, 1H- and 13C-NMR spectroscopy and single crystal X-ray crystallography. Using this ligand, a new mononuclear vanadium (III) complex, {2,6-[(3,5-ph2pz)CH2]2py}VCl3 was prepared and characterized by elemental analysis, ATR-IR and HR-MS. The complex was investigated as a catalyst for ethylene polymerization and compared with 2,6-[(3,5-Me2pz)CH2]2py}VCl3 to explore the effect of the substituent on the pyrazolyl rings on ethylene polymerization. High catalytic activity was observed at ambient temperature. After treatment with AlEtCl2, these complexes showed high activity for ethylene polymerization converting ethylene to highly linear polyethylene and affording high molecular weight polymers (up to 1.0 × 106 g/mol) with unimodal molecular weight distributions. Full article
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Open AccessArticle New Amide Derivatives of Quinoxaline 1,4-di-N-Oxide with Leishmanicidal and Antiplasmodial Activities
Molecules 2013, 18(4), 4718-4727; https://doi.org/10.3390/molecules18044718
Received: 26 March 2013 / Revised: 11 April 2013 / Accepted: 18 April 2013 / Published: 22 April 2013
Cited by 21 | Viewed by 2912 | PDF Full-text (192 KB) | HTML Full-text | XML Full-text
Abstract
Malaria and leishmaniasis are two of the World’s most important tropical parasitic diseases. Continuing with our efforts to identify new compounds active against malaria and leishmaniasis, twelve new 1,4-di-N-oxide quinoxaline derivatives were synthesized and evaluated for their in vitro antimalarial and
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Malaria and leishmaniasis are two of the World’s most important tropical parasitic diseases. Continuing with our efforts to identify new compounds active against malaria and leishmaniasis, twelve new 1,4-di-N-oxide quinoxaline derivatives were synthesized and evaluated for their in vitro antimalarial and antileishmanial activity against Plasmodium falciparum FCR-3 strain, Leishmania infantum and Leishmania amazonensis. Their toxicity against VERO cells (normal monkey kidney cells) was also assessed. The results obtained indicate that a cyclopentyl derivative had the best antiplasmodial activity (2.9 µM), while a cyclohexyl derivative (2.5 µM) showed the best activity against L. amazonensis, and a 3-chloropropyl derivative (0.7 µM) showed the best results against L. infantum. All these compounds also have a Cl substituent in the R7 position. Full article
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Open AccessReview Applications of Biomaterials to Liquid Crystals
Molecules 2013, 18(4), 4703-4717; https://doi.org/10.3390/molecules18044703
Received: 17 January 2013 / Revised: 10 April 2013 / Accepted: 17 April 2013 / Published: 19 April 2013
Cited by 20 | Viewed by 3070 | PDF Full-text (369 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, chemically synthesized proteins and peptides are attractive building blocks and have potential in many important applications as biomaterials. In this review, applications of biomaterials to thermotropic liquid crystals are discussed. The review covers the improvement of the performance of liquid crystal displays
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Nowadays, chemically synthesized proteins and peptides are attractive building blocks and have potential in many important applications as biomaterials. In this review, applications of biomaterials to thermotropic liquid crystals are discussed. The review covers the improvement of the performance of liquid crystal displays using liquid crystal physical gels consisting of a liquid crystal and amino acid-based gelators, and also new functionalization of liquid crystals. Moreover, the influence of DNA, which is one of the more attractive biomaterials, dispersed in thermotropic liquid crystals and its potential use in the liquid crystal industry is described. In addition, we found interesting results during electrooptical measurements of liquid crystals doped with DNA, and explain them from the point of view of biological applications. These recent approaches suggest that these biomaterials may be applicable in the electronic device industry and should be considered as an interesting material with their physical properties having the potential to create or refine an industrial product. Full article
(This article belongs to the Special Issue Chemical Protein and Peptide Synthesis)
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Open AccessArticle Resveratrol Protects against Physical Fatigue and Improves Exercise Performance in Mice
Molecules 2013, 18(4), 4689-4702; https://doi.org/10.3390/molecules18044689
Received: 4 February 2013 / Revised: 17 April 2013 / Accepted: 18 April 2013 / Published: 19 April 2013
Cited by 54 | Viewed by 7091 | PDF Full-text (2944 KB) | HTML Full-text | XML Full-text
Abstract
Resveratrol (RES) is a well-known phytocompound and food component which has antioxidative and multifunctional bioactivities. However, there is limited evidence for the effects of RES on physical fatigue and exercise performance. The purpose of this study was to evaluate the potential beneficial effects
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Resveratrol (RES) is a well-known phytocompound and food component which has antioxidative and multifunctional bioactivities. However, there is limited evidence for the effects of RES on physical fatigue and exercise performance. The purpose of this study was to evaluate the potential beneficial effects of trans-RES on fatigue and ergogenic functions following physiological challenge. Male ICR mice from four groups (n = 8 per group) were orally administered RES for 21 days at 0, 25, 50, and 125 mg/kg/day, which were respectively designated the vehicle, RES-25, RES-50, and RES-125 groups. The anti-fatigue activity and exercise performance were evaluated using forelimb grip strength, exhaustive swimming time, and levels of serum lactate, ammonia, glucose, and creatine kinase (CK) after a 15-min swimming exercise. The exhaustive swimming time of the RES-25 group (24.72 ± 7.35 min) was significantly (p = 0.0179) longer than that of vehicle group (10.83 ± 1.15 min). A trend analysis revealed that RES treatments increased the grip strength. RES supplementation also produced dose-dependent decreases in serum lactate and ammonia levels and CK activity and also an increase in glucose levels in dose-dependent manners after the 15-min swimming test. The mechanism was related to the increased energy utilization (as blood glucose), and decreased serum levels of lactate, ammonia, and CK. Therefore, RES could be a potential agent with an anti-fatigue pharmacological effect. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle Microwave-Assisted Synthesis of New Selenazole Derivatives with Antiproliferative Activity
Molecules 2013, 18(4), 4679-4688; https://doi.org/10.3390/molecules18044679
Received: 11 March 2013 / Revised: 12 April 2013 / Accepted: 17 April 2013 / Published: 19 April 2013
Cited by 13 | Viewed by 2611 | PDF Full-text (212 KB) | HTML Full-text | XML Full-text
Abstract
New aryl-hydrazinyl-1,3-selenazole and aroyl-hydrazonyl-1,3-selenazoles were synthesized via Hantzsch type condensation reactions of selenosemicarbazides with α-halogenocarbonyl derivatives, under classical versus microwave heating conditions. Excellent yields and shorter reaction times were obtained under irradiation conditions. The structures of the synthesized compounds were assigned based on
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New aryl-hydrazinyl-1,3-selenazole and aroyl-hydrazonyl-1,3-selenazoles were synthesized via Hantzsch type condensation reactions of selenosemicarbazides with α-halogenocarbonyl derivatives, under classical versus microwave heating conditions. Excellent yields and shorter reaction times were obtained under irradiation conditions. The structures of the synthesized compounds were assigned based on spectroscopic data (FT-IR, 1H-NMR), MS and elemental analysis. Selenazole derivatives were screened for their anti-proliferative effects against two leukemia cell lines (CCRF-CEM and HL60) and three carcinoma cell lines (MDA-MB231, HCT116 and U87MG). Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle Synthesis and Antimicrobial Activity of Some New Thieno[2,3-b]thiophene Derivatives
Molecules 2013, 18(4), 4669-4678; https://doi.org/10.3390/molecules18044669
Received: 28 March 2013 / Revised: 10 April 2013 / Accepted: 16 April 2013 / Published: 19 April 2013
Cited by 10 | Viewed by 2436 | PDF Full-text (305 KB) | HTML Full-text | XML Full-text
Abstract
A series of thieno[2,3-b]thiophene moiety-containing bis-cyanopyrazoles 5ac, bis-aminopyrazole 9 and bis-pyridazine derivatives 11 were synthesized and evaluated in vitro for their antimicrobial potential. The antimicrobial activity of some selected products was evaluated and showed good
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A series of thieno[2,3-b]thiophene moiety-containing bis-cyanopyrazoles 5ac, bis-aminopyrazole 9 and bis-pyridazine derivatives 11 were synthesized and evaluated in vitro for their antimicrobial potential. The antimicrobial activity of some selected products was evaluated and showed good results. 5,5'-(3,4-Dimethylthieno[2,3-b]thiophene-2,5-diyl)bis(3-acetyl-1-(4-chlorophenyl)-1H-pyrazole-4-carbonitrile) (5d) was found to be more potent than the standard drug amphotericin B against Geotricum candidum and equipotent to amphotericin B against Syncephalastrum racemosum. In addition, it was found to be equipotent to the standard drug Penicillin G against Staphylococcus aureus. Moreover, it was more potent than the standard drug streptomycin against Pseudomonas aeruginosa and Escherichia coli. Full article
(This article belongs to the Section Organic Chemistry)
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Open AccessArticle Evaluation of Biological Value and Appraisal of Polyphenols and Glucosinolates from Organic Baby-Leaf Salads as Antioxidants and Antimicrobials against Important Human Pathogenic Bacteria
Molecules 2013, 18(4), 4651-4668; https://doi.org/10.3390/molecules18044651
Received: 14 March 2013 / Revised: 12 April 2013 / Accepted: 17 April 2013 / Published: 19 April 2013
Cited by 6 | Viewed by 3575 | PDF Full-text (340 KB) | HTML Full-text | XML Full-text
Abstract
The present investigation has been carried out to investigate the biological role of four different types of baby-leaf salads and to study their potential as natural sources of antioxidants and antimicrobials against several isolates from important human pathogenic bacteria. Four single types of
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The present investigation has been carried out to investigate the biological role of four different types of baby-leaf salads and to study their potential as natural sources of antioxidants and antimicrobials against several isolates from important human pathogenic bacteria. Four single types of salads (green lettuce, red lettuce, rucola and watercress) and two mixtures [(1) red lettuce+green lettuce; (2) green lettuce + red lettuce + watercress + rucola] were assayed. The HPLC analysis revealed interesting levels of polyphenols and glucosinolates. The results showed a significant variation (p < 0.05) of polyphenols and glucosinolates with plant material. Nine different types of polyphenols grouped in three major classes were found: gallic acid, chlorogenic acid, caffeic acid and dicaffeoyltartaric acid (phenolic acids); quercitin-3-O-rutinoside, quercitin-3-O-rhamnoside, luteolin-7-O-glucoside and isorhamnetin (flavonoids); and cyanidin-3-glucoside (anthocyanins). Only three different glucosinolates were found: glucoraphanin; gluconasturtiin and 4-methoxy-glucobrassicin. A positive correlation was detected between polyphenol contents and antioxidant activity. Red lettuce and mixture 1 were the baby-leaf salads with the highest antioxidant potential. As for the antimicrobial activity, the results showed a selective effect of chemicals against Gram-positive and Gram-negative bacteria and Enterococcus faecalis and Staphylococcus aureus were the bacteria most affected by the phytochemicals. Based on the results achieved baby-leaf salads represent an important source of natural antioxidants and antimicrobial substances. Full article
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Open AccessCommunication Arabinoxylan Microspheres: Structural and Textural Characteristics
Molecules 2013, 18(4), 4640-4650; https://doi.org/10.3390/molecules18044640
Received: 8 February 2013 / Revised: 7 April 2013 / Accepted: 8 April 2013 / Published: 19 April 2013
Cited by 13 | Viewed by 2815 | PDF Full-text (586 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this research was to study the structural and textural characteristics of maize bran arabinoxylan (MBAX) microspheres. The laccase-induced cross-linking process was monitored by storage (G') and loss (G'') moduli changes in a 4% (w/v) MBAX solution. The G' and G''
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The aim of this research was to study the structural and textural characteristics of maize bran arabinoxylan (MBAX) microspheres. The laccase-induced cross-linking process was monitored by storage (G') and loss (G'') moduli changes in a 4% (w/v) MBAX solution. The G' and G'' values at the plateau region were 215 and 4 Pa, respectively. After gelation, the content of ferulic acid dimers decreased from 0.135 to 0.03 µg/mg MBAX, suggesting the formation of ferulated structures unreleased by mild alkaline hydrolysis. MBAX microspheres presented an average diameter of 531 µm and a swelling ratio value (q) of 18 g water/g MBAX. The structural parameters of MBAX microspheres were calculated from equilibrium swelling experiments, presenting an average mesh size of 52 nm. Microstructure and textural properties of dried MBAX microspheres were studied by scanning electron microscopy and nitrogen adsorption/desorption isotherms, respectively, showing a heterogeneous mesoporous and macroporous structure throughout the network. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessCommunication A Series of Asymmetrical Phthalocyanines: Synthesis and Near Infrared Properties
Molecules 2013, 18(4), 4628-4639; https://doi.org/10.3390/molecules18044628
Received: 30 January 2013 / Revised: 7 April 2013 / Accepted: 8 April 2013 / Published: 19 April 2013
Cited by 4 | Viewed by 3050 | PDF Full-text (390 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We report here the preparation of asymmetrical phthalocyanine dimers 1a3a, which are endowed with novel charge transfer bands at 1,151–1,154 nm and strong NIR luminescences at 840–860 nm and 1,600–1,650 nm. Through H-bonding interaction, 1a3a are inclined to
[...] Read more.
We report here the preparation of asymmetrical phthalocyanine dimers 1a3a, which are endowed with novel charge transfer bands at 1,151–1,154 nm and strong NIR luminescences at 840–860 nm and 1,600–1,650 nm. Through H-bonding interaction, 1a3a are inclined to self-assemble into hexrod nanotubes at the interface of CHCl3 and CH3OH. Our results provide further insights into the interaction in molecular dimers, and suggest that 1a3a have potential application in magnets and supramolecular architectures. Full article
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Open AccessArticle Synthesis of New 1,2,3-Triazole Derivatives of Uracil and Thymine with Potential Inhibitory Activity against Acidic Corrosion of Steels
Molecules 2013, 18(4), 4613-4627; https://doi.org/10.3390/molecules18044613
Received: 26 January 2013 / Revised: 11 April 2013 / Accepted: 16 April 2013 / Published: 18 April 2013
Cited by 20 | Viewed by 3142 | PDF Full-text (298 KB) | HTML Full-text | XML Full-text
Abstract
Ten 1,4-disubstituted 1,2,3-triazoles were synthesized from one of 1-(azido-methyl)benzene, 1-(azidomethyl)-4-fluorobenzene, 1-(azidomethyl)-4-chlorobenzene, 1-(azidomethyl)-4-bromobenzene or 1-(azidomethyl)-4-iodobenzene, generated in situ from sodium azide and the corresponding benzyl halide, and dipropargyl uracil or dipropargyl thymine. Optimal experimental conditions were established for the conventional click chemistry. The corrosion
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Ten 1,4-disubstituted 1,2,3-triazoles were synthesized from one of 1-(azido-methyl)benzene, 1-(azidomethyl)-4-fluorobenzene, 1-(azidomethyl)-4-chlorobenzene, 1-(azidomethyl)-4-bromobenzene or 1-(azidomethyl)-4-iodobenzene, generated in situ from sodium azide and the corresponding benzyl halide, and dipropargyl uracil or dipropargyl thymine. Optimal experimental conditions were established for the conventional click chemistry. The corrosion inhibiting properties of some of these compounds, which were determined by means of an electrochemical technique, are also presented. Full article
(This article belongs to the Section Organic Chemistry)
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Open AccessArticle Functionalization of Multi-Walled Carbon Nanotubes with Thermo-Responsive Azide-Terminated Poly(N-isopropylacrylamide) via Click Reactions
Molecules 2013, 18(4), 4599-4612; https://doi.org/10.3390/molecules18044599
Received: 24 January 2013 / Revised: 10 April 2013 / Accepted: 15 April 2013 / Published: 18 April 2013
Cited by 12 | Viewed by 3132 | PDF Full-text (404 KB) | HTML Full-text | XML Full-text
Abstract
Covalently functionalized multi-walled carbon nanotubes (MWNTs) were prepared by grafting well-defined thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) via click reactions. First, azide-terminated poly(N-isopropylacrylamide) (N3-PNIPAM) was synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization, and then the N3-PNIPAM moiety
[...] Read more.
Covalently functionalized multi-walled carbon nanotubes (MWNTs) were prepared by grafting well-defined thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) via click reactions. First, azide-terminated poly(N-isopropylacrylamide) (N3-PNIPAM) was synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization, and then the N3-PNIPAM moiety was connected onto MWNTs by click chemistry. The products were characterized by means of FT-IR, TGA and TEM. The results show that the modification of MWNTs is very successful and MWNTs functionalized by N3-PNIPAM (MWNTs-PNIPAM) have good solubility and stability in water. TEM images show the functionalized MWNTs are dispersed individually, indicating that the bundles of original MWNTs are separated into individual tubes by surface modification with polymer chains. These MWNTs modified with PNIPAM represent a potential nano-material for preparation of hydrophilic composite materials. Full article
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Open AccessArticle Chemical Composition, Cytotoxic and Antimicrobial Activity of Essential Oils from Cassia bakeriana Craib. against Aerobic and Anaerobic Oral Pathogens
Molecules 2013, 18(4), 4588-4598; https://doi.org/10.3390/molecules18044588
Received: 21 March 2013 / Revised: 16 April 2013 / Accepted: 16 April 2013 / Published: 18 April 2013
Cited by 11 | Viewed by 3588 | PDF Full-text (217 KB) | HTML Full-text | XML Full-text
Abstract
The chemical composition of the essential oils from leaves, bark and wood of Cassia bakeriana Craib. was determined by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). Alcohols, aldehydes and fatty acids were the major components in leaf and bark oil, while wood
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The chemical composition of the essential oils from leaves, bark and wood of Cassia bakeriana Craib. was determined by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). Alcohols, aldehydes and fatty acids were the major components in leaf and bark oil, while wood essential oil was rich in fatty acids. Terpenes such as linalool, (E)-nerolidol and phytol were present in low concentrations. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated using the microdilution method, as was the cell viability test carried out with Vero cells. The oils from leaves and bark showed high antimicrobial activity, with minimum inhibitory concentrations between 62.5 and 125 µg·mL−1 for most of the tested bacteria, including Streptococcus mutans, the main etiological agent of dental caries. Leaves oil displayed the lowest cytotoxic effect (EC50 of 153 µg·mL−1), while wood oil exhibited the highest toxicity to Vero cells. C. bakeriana oils are thus a source of biologically active compounds against aerobic and anaerobic oral microorganisms. This study is the first report on the chemical composition, antimicrobial activity and cytotoxicity of C. bakeriana. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle Triacylglyceride, Antioxidant and Antimicrobial Features of Virgin Camellia oleifera, C. reticulata and C. sasanqua Oils
Molecules 2013, 18(4), 4573-4587; https://doi.org/10.3390/molecules18044573
Received: 13 March 2013 / Revised: 9 April 2013 / Accepted: 15 April 2013 / Published: 18 April 2013
Cited by 14 | Viewed by 2987 | PDF Full-text (317 KB) | HTML Full-text | XML Full-text
Abstract
Virgin oils obtained from seeds of Camellia oleifera (CO), Camellia reticulata (CR) and Camellia sasanqua (CS) were studied for their triacylglyceride composition, antioxidant and antimicrobial activities. Levels of fatty acids determined by 1H-nuclear magnetic resonance analysis were similar to those reported for
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Virgin oils obtained from seeds of Camellia oleifera (CO), Camellia reticulata (CR) and Camellia sasanqua (CS) were studied for their triacylglyceride composition, antioxidant and antimicrobial activities. Levels of fatty acids determined by 1H-nuclear magnetic resonance analysis were similar to those reported for olive oils (82.30%–84.47%; 5.69%–7.78%; 0.26%–0.41% and 8.04%–11.2%, for oleic, linoleic, linolenic and saturated acids, respectively). The CR oil showed the best antioxidant potential in the three in vitro models tested. With regard to EC50 values (µg/mL), the order in DPPH radical-scavenging was CR (33.48) < CO (35.20) < CS (54.87). Effectiveness in reducing power was CR (2.81) < CO (3.09) < CS (5.32). IC50 for LPO inhibition were 0.37, 0.52 and 0.75 µg/mL for CR, CO and CS, respectively. All the oils showed antimicrobial activity, and exhibited different selectivity and MICs for each microorganism tested (E. coli, B. cereus and C. albicans). B. cereus was the less sensitive species (MIC: 52.083 ± 18.042 for CO; 41.667 ± 18.042 for CR; 104.167 ± 36.084 for CS mg/mL) and the E. coli was the most sensitive to camellia oil’s effect. The standard gentamicin presented higher MIC for E. coli (4.2) than the CR (MIC= 2.6) and CO (MIC = 3.9) oils. Full article
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Open AccessArticle Synthesis, Biological Evaluation, and Pharmacokinetic Study of Novel Liguzinediol Prodrugs
Molecules 2013, 18(4), 4561-4572; https://doi.org/10.3390/molecules18044561
Received: 15 March 2013 / Revised: 8 April 2013 / Accepted: 11 April 2013 / Published: 18 April 2013
Cited by 8 | Viewed by 2577 | PDF Full-text (275 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Liguzinediol (LZDO) ester prodrugs 35 were synthesized and evaluated in vitro and in vivo for their potential use in prolonging the half-life of the parent drug LZDO (1a) in vivo. Prodrugs 35 were found to display
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Liguzinediol (LZDO) ester prodrugs 35 were synthesized and evaluated in vitro and in vivo for their potential use in prolonging the half-life of the parent drug LZDO (1a) in vivo. Prodrugs 35 were found to display a potent positive inotropic effect on the myocardium, without the risk of arrhythmia. Prodrugs 35 rapidly underwent enzymatic hydrolysis to release the parent compound LZDO in 1–3 h in rat liver microsomes and rat plasma. The half-life of the parent compound was prolonged after intragastric administration of prodrug 3, which was found to be a superior prodrug candidate for increasing myocardial contractility. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle Deuterium Isotope Effects on 13C-NMR Chemical Shifts of 10-Hydroxybenzo[h]quinolines
Molecules 2013, 18(4), 4544-4560; https://doi.org/10.3390/molecules18044544
Received: 1 March 2013 / Revised: 9 April 2013 / Accepted: 15 April 2013 / Published: 17 April 2013
Cited by 9 | Viewed by 2940 | PDF Full-text (304 KB) | HTML Full-text | XML Full-text
Abstract
Deuterium isotope effects on 13C-NMR chemical shifts are investigated in a series of 10-hydroxybenzo[h]quinolines (HBQ’s) The OH proton is deuteriated. The isotope effects on 13C chemical shifts in these hydrogen bonded systems are rather unusual. The formal four-bond effects
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Deuterium isotope effects on 13C-NMR chemical shifts are investigated in a series of 10-hydroxybenzo[h]quinolines (HBQ’s) The OH proton is deuteriated. The isotope effects on 13C chemical shifts in these hydrogen bonded systems are rather unusual. The formal four-bond effects are found to be negative, indicating transmission via the hydrogen bond. In addition unusual long-range effects are seen. Structures, NMR chemical shifts and changes in nuclear shieldings upon deuteriation are calculated using DFT methods. Two-bond deuterium isotope effects on 13C chemical shifts are correlated with calculated OH stretching frequencies. Isotope effects on chemical shifts are calculated for systems with OH exchanged by OD. Hydrogen bond potentials are discussed. New and more soluble nitro derivatives are synthesized. Full article
(This article belongs to the Special Issue Isotope Effects)
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Open AccessArticle Synthesis, Structure and Cytotoxic Activity of New Acetylenic Derivatives of Betulin
Molecules 2013, 18(4), 4526-4543; https://doi.org/10.3390/molecules18044526
Received: 21 March 2013 / Revised: 8 April 2013 / Accepted: 11 April 2013 / Published: 17 April 2013
Cited by 25 | Viewed by 3346 | PDF Full-text (393 KB) | HTML Full-text | XML Full-text
Abstract
A new series of betulin derivatives containing one or two pharmacophores bearing an acetylenic and carbonyl function at the C-3 and/or C-28 positions has been synthesized and characterized by 1H- and 13C-NMR, IR, MS and elemental analyses. The crystal structure of
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A new series of betulin derivatives containing one or two pharmacophores bearing an acetylenic and carbonyl function at the C-3 and/or C-28 positions has been synthesized and characterized by 1H- and 13C-NMR, IR, MS and elemental analyses. The crystal structure of 28-O-propynoylbetulin was determined by X-ray structural analysis. All new compounds, as well as betulin, were tested in vitro for their antiproliferative activity against human SW707 colorectal, CCRF/CEM leukemia, T47D breast cancer, and against murine P388 leukemia and Balb3T3 normal fibroblasts cell lines. Most of the compounds showed better cytotoxicity than betulin and cisplatin used as reference agent. 28-O-Propynoylbetulin was the most potent derivative, being over 500 times more potent than betulin and about 100 times more cytotoxic than cisplatin against the human leukemia (CCRF/CEM) cell line, with an ID50 value of 0.02 μg/mL. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle The Use of Bio-Guided Fractionation to Explore the Use of Leftover Biomass in Dutch Flower Bulb Production as Allelochemicals against Weeds
Molecules 2013, 18(4), 4510-4525; https://doi.org/10.3390/molecules18044510
Received: 28 February 2013 / Revised: 28 March 2013 / Accepted: 12 April 2013 / Published: 17 April 2013
Cited by 2 | Viewed by 2962 | PDF Full-text (649 KB) | HTML Full-text | XML Full-text
Abstract
A major problem in flower bulb cultivation is weed control. Synthetic herbicides are mainly used, although they cause a range of problems, and integrated weed control through application of naturally occurring allelochemicals would be highly desirable. Flower bulb production creates large amounts of
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A major problem in flower bulb cultivation is weed control. Synthetic herbicides are mainly used, although they cause a range of problems, and integrated weed control through application of naturally occurring allelochemicals would be highly desirable. Flower bulb production creates large amounts of leftover biomass. Utilizing this source for weed control may provide new applications of the bulb crops. We therefore screened 33 flower bulb extracts for allelochemical activity against weeds. Several methanol and chloroform extracts were observed to inhibit germination and growth of Senecio vulgaris L. and Lolium perenne L., as representatives of di- and mono-cotyledonous weeds, respectively. Narciclasine was identified as the bioactive compound in Narcissus. The extract of Amaryllis belladonna L. was equally active, but did not contain any narciclasine. Bioassay-guided fractionation of the A. belladonna extract resulted in the identification of lycorine as the bio-active compound. The IC50 measured for radicle growth inhibition was 0.10 µM for narciclasine and 0.93 µM for lycorine, compared to 0.11 mM of chlorpropham, a synthetic herbicide. Therefore, the leftover biomass from the spring bulb industry represents an interesting potential source for promising allelochemicals for further studies on weed growth inhibition. Full article
(This article belongs to the Special Issue Bioassay-Guided Isolation of Natural Products)
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Open AccessArticle Synthesis and Biological Evaluation of Thieno[3,2-d]- pyrimidinones, Thieno[3,2-d]pyrimidines and Quinazolinones: Conformationally Restricted 17b-Hydroxysteroid Dehydrogenase Type 2 (17b-HSD2) Inhibitors
Molecules 2013, 18(4), 4487-4509; https://doi.org/10.3390/molecules18044487
Received: 22 March 2013 / Revised: 8 April 2013 / Accepted: 10 April 2013 / Published: 16 April 2013
Cited by 5 | Viewed by 2720 | PDF Full-text (418 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a series of conformationally restricted thieno[3,2-d]pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones was designed and synthesized with the goal of improving the biological activity as 17b-hydroxysteroid dehydrogenase type 2 inhibitors of the corresponding amidothiophene derivatives. Two moderately active compounds
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In this study, a series of conformationally restricted thieno[3,2-d]pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones was designed and synthesized with the goal of improving the biological activity as 17b-hydroxysteroid dehydrogenase type 2 inhibitors of the corresponding amidothiophene derivatives. Two moderately active compounds were discovered and this allowed the identification of the biologically active open conformer as well as the extension of the enzyme binding site characterisation. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle Chemical Constituents from the Leaves of Annona reticulata and Their Inhibitory Effects on NO Production
Molecules 2013, 18(4), 4477-4486; https://doi.org/10.3390/molecules18044477
Received: 24 January 2013 / Revised: 3 April 2013 / Accepted: 12 April 2013 / Published: 16 April 2013
Cited by 11 | Viewed by 3212 | PDF Full-text (231 KB) | HTML Full-text | XML Full-text
Abstract
In the present study, the chemical investigation of the leaves of Annona reticulata has resulted in the identification of nine compounds, including annonaretin A, (1), a new triterpenoid. The purified compounds were subjected to the examination of their effects on NO
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In the present study, the chemical investigation of the leaves of Annona reticulata has resulted in the identification of nine compounds, including annonaretin A, (1), a new triterpenoid. The purified compounds were subjected to the examination of their effects on NO inhibition in LPS-activated mouse peritoneal macrophages and most of them exhibited significant NO inhibition, with IC50 values in the range of 48.6 ± 1.2 and 99.8 ± 0.4 μM. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessReview H/D Isotope Effects in Hydrogen Bonded Systems
Molecules 2013, 18(4), 4467-4476; https://doi.org/10.3390/molecules18044467
Received: 26 February 2013 / Revised: 18 March 2013 / Accepted: 5 April 2013 / Published: 16 April 2013
Cited by 32 | Viewed by 3516 | PDF Full-text (562 KB) | HTML Full-text | XML Full-text
Abstract
An extremely strong H/D isotope effect observed in hydrogen bonded A-HB systems is connected with a reach diversity of the potential shape for the proton/deuteron motion. It is connected with the anharmonicity of the proton/deuteron vibrations and of the tunneling effect,
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An extremely strong H/D isotope effect observed in hydrogen bonded A-HB systems is connected with a reach diversity of the potential shape for the proton/deuteron motion. It is connected with the anharmonicity of the proton/deuteron vibrations and of the tunneling effect, particularly in cases of short bridges with low barrier for protonic and deuteronic jumping. Six extreme shapes of the proton motion are presented starting from the state without possibility of the proton transfer up to the state with a full ionization. The manifestations of the H/D isotope effect are best reflected in the infra-red absorption spectra. A most characteristic is the run of the relationship between the isotopic ratio nH/nD and position of the absorption band shown by using the example of NHN hydrogen bonds. One can distinguish a critical range of correlation when the isotopic ratio reaches the value of ca. 1 and then increases up to unusual values higher than . The critical range of the isotope effect is also visible in NQR and NMR spectra. In the critical region one observes a stepwise change of the NQR frequency reaching 1.1 MHz. In the case of NMR, the maximal isotope effect is reflected on the curve presenting the dependence of Δd (1H,2H) on d (1H). This effect corresponds to the range of maximum on the correlation curve between dH and ΔpKa that is observed in various systems. There is a lack in the literature of quantitative information about the influence of isotopic substitution on the dielectric properties of hydrogen bond except the isotope effect on the ferroelectric phase transition in some hydrogen bonded crystals. Full article
(This article belongs to the Special Issue Isotope Effects)
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Open AccessArticle Phosphorus Dendrimers as Carriers of siRNA—Characterisation of Dendriplexes
Molecules 2013, 18(4), 4451-4466; https://doi.org/10.3390/molecules18044451
Received: 18 March 2013 / Revised: 3 April 2013 / Accepted: 11 April 2013 / Published: 15 April 2013
Cited by 17 | Viewed by 3657 | PDF Full-text (545 KB) | HTML Full-text | XML Full-text
Abstract
There are many types of dendrimers used as nanomolecules for gene delivery but there is still an ongoing search for ones that are able to effectively deliver drugs to cells. The possibility of gene silencing using siRNA gives hope for effective treatment of
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There are many types of dendrimers used as nanomolecules for gene delivery but there is still an ongoing search for ones that are able to effectively deliver drugs to cells. The possibility of gene silencing using siRNA gives hope for effective treatment of numerous diseases. The aim of this work was to investigate in vitro biophysical properties of dendriplexes formed by siRNA and cationic phosphorus dendrimers of 3rd and 4th generation. First, using the ethidium bromide intercalation method, it was examined whether dendrimers have an ability to form complexes with siRNA. Next, the characterisation of dendriplexes formed at different molar ratios was carried out using biophysical methods. The effects of zeta potential, size and changes of siRNA conformation on the complexation with dendrimers were examined. It was found that both phosphorus dendrimers interacted with siRNA. The zeta potential values of dendriplexes ranged from negative to positive and the hydrodynamic diameter depended on the number of dendrimer molecules in the complex. Furthermore, using circular dichroism spectroscopy it was found that cationic phosphorus dendrimers changed only slightly the shape of siRNA CD spectra, thus they did not induce significant changes in the nucleic acid secondary structure during complex formation. Full article
(This article belongs to the Special Issue Dendrimers in Medicine and Biotechnology)
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Open AccessArticle Hydrophobic Effect of Amphiphilic Derivatives of Chitosan on the Antifungal Activity against Aspergillus flavus and Aspergillus parasiticus
Molecules 2013, 18(4), 4437-4450; https://doi.org/10.3390/molecules18044437
Received: 19 February 2013 / Revised: 20 March 2013 / Accepted: 9 April 2013 / Published: 15 April 2013
Cited by 11 | Viewed by 3137 | PDF Full-text (528 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Low molecular weight amphiphilic derivatives of chitosan were synthesized, characterized and their antifungal activities against Aspergillus flavus and Aspergillus parasiticus were tested. The derivatives were synthesized using as starting material a deacetylated chitosan sample in a two step process: the reaction with propyltrimethyl-ammonium
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Low molecular weight amphiphilic derivatives of chitosan were synthesized, characterized and their antifungal activities against Aspergillus flavus and Aspergillus parasiticus were tested. The derivatives were synthesized using as starting material a deacetylated chitosan sample in a two step process: the reaction with propyltrimethyl-ammonium bromide (Pr), followed by reductive amination with dodecyl aldehyde. Aiming to evaluate the effect of the hydrophobic modification of the derivatives on the antifungal activity against the pathogens, the degree of substitution (DS1) by Pr groups was kept constant and the proportion of dodecyl (Dod) groups was varied from 7 to 29% (DS2). The derivatives were characterized by 1H-NMR and FTIR and their antifungal activities against the pathogens were tested by the radial growth of the colony and minimum inhibitory concentration (MIC) methods. The derivatives substituted with only Pr groups exhibited modest inhibition against A. flavus and A. parasiticus, like that obtained with deacetylated chitosan. Results revealed that the amphiphilic derivatives grafted with Dod groups exhibited increasing inhibition indexes, depending on polymer concentration and hydrophobic content. At 0.6 g/L, all amphiphilic derivatives having from 7.0 to 29% of Dod groups completely inhibited fungal growth and the MIC values were found to decrease from 4.0 g/L for deacetylated chitosan to 0.25–0.50 g/L for the derivatives. These new derivatives open up the possibility of new applications and avenues to develop effective biofungicides based on chitosan. Full article
(This article belongs to the Special Issue Chitins and Chitosans)
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Open AccessArticle Evaluation of the Biological Activity of Naturally Occurring 5,8-Dihydroxycoumarin
Molecules 2013, 18(4), 4419-4436; https://doi.org/10.3390/molecules18044419
Received: 19 February 2013 / Revised: 21 March 2013 / Accepted: 9 April 2013 / Published: 15 April 2013
Cited by 7 | Viewed by 3100 | PDF Full-text (468 KB) | HTML Full-text | XML Full-text
Abstract
5,8-Dihydroxycoumarin (5,8-DHC) was isolated from aerial parts of sweet grass (Hierochloë odorata L.) and screened for antioxidant and genotoxic activities. A clear linear dependency of radical scavenging capacity in DPPH and ABTS•+ assays was determined. 5,8-DHC was very efficient in
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5,8-Dihydroxycoumarin (5,8-DHC) was isolated from aerial parts of sweet grass (Hierochloë odorata L.) and screened for antioxidant and genotoxic activities. A clear linear dependency of radical scavenging capacity in DPPH and ABTS•+ assays was determined. 5,8-DHC was very efficient in retarding rapeseed oil oxidation (Oxipress test). TPC (total phenols content) and FRAP (the ability to reduce ferric ion to ferrous ion) assays revealed a somewhat lower antioxidant capacity of 5,8-DHC as compared with gallic acid. Genotoxic activity was tested using different genetic end-points: chromosome aberrations (CAs) and micronuclei (MN) in Wistar rat bone marrow in vivo, CAs and sister chromatid exchanges (SCEs) in human lymphocytes in vitro, and somatic mutations and recombination in Drosophila melanogaster wing cells in vivo. 5,8-DHC did not increase frequency of CAs in rat bone marrow cells, but induced a significant increase of MN. It was slightly mutagenic in the Drosophila melanogaster assay after 120 h of treatment, but not after 48 h of treatment. 5,8-DHC induced both CAs and SCEs in vitro in human lymphocytes in a clear dose-dependent manner. Thus, 5,8-DHC may be classified as weakly genotoxic both in vivo and in vitro. Full article
(This article belongs to the Special Issue Phytochemicals: Analytical and Medicinal Chemistry)
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Open AccessArticle Palladium(II)-Catalyzed othro-C–H-Benzoxylation of 2-Arylpyridines by Oxidative Coupling with Aryl Acylperoxides
Molecules 2013, 18(4), 4403-4418; https://doi.org/10.3390/molecules18044403
Received: 5 March 2013 / Revised: 21 March 2013 / Accepted: 21 March 2013 / Published: 15 April 2013
Cited by 15 | Viewed by 2855 | PDF Full-text (254 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A palladium(II)-catalyzed ortho-benzoxylation of 2-arylpyridines with aryl acylperoxides was developed. With pyridyl as directing group, the benzoxylation reaction exhibits remarkable regioselectivity and excellent functional group tolerance, providing the products in up to 87% yield. Full article
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