Next Issue
Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Molecules, Volume 16, Issue 10 (October 2011), Pages 8143-8929

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-52
Export citation of selected articles as:
Open AccessArticle Determination of Capsaicin and Dihydrocapsaicin in Capsicum Fruit Samples using High Performance Liquid Chromatography
Molecules 2011, 16(10), 8919-8929; https://doi.org/10.3390/molecules16108919
Received: 22 August 2011 / Revised: 14 October 2011 / Accepted: 15 October 2011 / Published: 24 October 2011
Cited by 75 | PDF Full-text (329 KB)
Abstract
The aim of the present study was to determine the content of capsaicin and dihydrocapsaicin in Capsicum samples collected from city markets in Riyadh (Saudi Arabia), calculate their pungency in Scoville heat units (SHU) and evaluate the average daily intake of capsaicin for
[...] Read more.
The aim of the present study was to determine the content of capsaicin and dihydrocapsaicin in Capsicum samples collected from city markets in Riyadh (Saudi Arabia), calculate their pungency in Scoville heat units (SHU) and evaluate the average daily intake of capsaicin for the population of Riyadh. The investigated samples consisted of hot chillies, red chillies, green chillies, green peppers, red peppers and yellow peppers. Extraction of capsaicinoids was done using ethanol as solvent, while high performance liquid chromatography (HPLC) was used for separation, identification and quantitation of the components. The limit of detection (LOD) of the method was 0.09 and 0.10 µg/g for capsaicin and dihydrocapsaicin, respectively, while the limit of quantification (LOQ) was 0.30 and 0.36 µg/g for capsaicin and dihydrocapsaicin, respectively. Hot chillies showed the highest concentration of capsaicin (4249.0 ± 190.3 µg/g) and the highest pungency level (67984.60 SHU), whereas green peppers had the lowest detected concentration (1.0 ± 0.9 µg/g); green peppers, red peppers and yellow peppers were non pungent. The mean consumption of peppers for Riyadh city population was determined to be 15.5 g/person/day while the daily capsaicin intake was 7.584 mg/person/day. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessReview Silver Nanoparticles as Potential Antiviral Agents
Molecules 2011, 16(10), 8894-8918; https://doi.org/10.3390/molecules16108894
Received: 1 September 2011 / Revised: 30 September 2011 / Accepted: 19 October 2011 / Published: 24 October 2011
Cited by 183 | PDF Full-text (380 KB)
Abstract
Virus infections pose significant global health challenges, especially in view of the fact that the emergence of resistant viral strains and the adverse side effects associated with prolonged use continue to slow down the application of effective antiviral therapies. This makes imperative the
[...] Read more.
Virus infections pose significant global health challenges, especially in view of the fact that the emergence of resistant viral strains and the adverse side effects associated with prolonged use continue to slow down the application of effective antiviral therapies. This makes imperative the need for the development of safe and potent alternatives to conventional antiviral drugs. In the present scenario, nanoscale materials have emerged as novel antiviral agents for the possibilities offered by their unique chemical and physical properties. Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses including human imunodeficiency virus, hepatitis B virus, herpes simplex virus, respiratory syncytial virus, and monkey pox virus. The use of metal nanoparticles provides an interesting opportunity for novel antiviral therapies. Since metals may attack a broad range of targets in the virus there is a lower possibility to develop resistance as compared to conventional antivirals. The present review focuses on the development of methods for the production of silver nanoparticles and on their use as antiviral therapeutics against pathogenic viruses. Full article
(This article belongs to the Special Issue Antivirals)
Open AccessArticle Autotoxicity and Allelopathy of 3,4-Dihydroxyacetophenone Isolated from Picea schrenkiana Needles
Molecules 2011, 16(10), 8874-8893; https://doi.org/10.3390/molecules16108874
Received: 19 September 2011 / Revised: 9 October 2011 / Accepted: 17 October 2011 / Published: 24 October 2011
Cited by 23 | PDF Full-text (2401 KB)
Abstract
Bioassay-guided fractionation of the diethyl ether fraction of a water extract of Picea schrenkiana needles led to the isolation of the phenolic compound 3,4-dihydroxy- acetophenone (DHAP). The allelopathic effects of DHAP were evaluated under laboratory conditions on P. schrenkiana, rice (Oryza
[...] Read more.
Bioassay-guided fractionation of the diethyl ether fraction of a water extract of Picea schrenkiana needles led to the isolation of the phenolic compound 3,4-dihydroxy- acetophenone (DHAP). The allelopathic effects of DHAP were evaluated under laboratory conditions on P. schrenkiana, rice (Oryza sativa L.), wheat (Triticum aestivum L.), radish (Raphanus sativus L.), lettuce (Latuca sativa L.), cucumber (Cucumis sativus L.) and mung bean (Phaseolus radiatus L.). DHAP significantly inhibited seed germination and seedling growth of P. schrenkiana at concentrations of 2.5 mM and 0.5 mM (p < 0.05). Soil analysis revealed that P. schrenkiana forest soils contained exceptionally high DHAP concentrations (mean = 0.51 ± 0.03 mg/g dry soil), sufficient to inhibit natural P. schrenkiana recruitment. DHAP also exhibited strong allelopathic potential. It significantly inhibited wheat and lettuce seed germination at concentrations of 1 mM and 0.5 mM (p < 0.05). The active compound also completely inhibited root growth of the six test species at high concentrations. Our results suggest a dual role of DHAP, both as an allelochemical and as an autotoxicant. The potential for a single plant needle-leached compound to influence both inter- and intra-specific interactions emphasized the complex effects that plant secondary metabolites might have on plant population and community structure. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessCommunication A New Languidulane Diterpenoid from Salvia mexicana var. mexicana
Molecules 2011, 16(10), 8866-8873; https://doi.org/10.3390/molecules16108866
Received: 27 September 2011 / Revised: 17 October 2011 / Accepted: 18 October 2011 / Published: 21 October 2011
Cited by 2 | PDF Full-text (179 KB) | Supplementary Files
Abstract
From the aerial parts of Salvia mexicana var. mexicana, two C-10 epimers (α and β) of salvimexicanolide were isolated. Our interpretation of the data, especially the 13C NMR, led us to conclude that the previously described 13C-NMR spectrum of the
[...] Read more.
From the aerial parts of Salvia mexicana var. mexicana, two C-10 epimers (α and β) of salvimexicanolide were isolated. Our interpretation of the data, especially the 13C NMR, led us to conclude that the previously described 13C-NMR spectrum of the α-epimer was not accurately assigned and it actually corresponds to the β-epimer. The structures proposed for the salvimexicanolides were verified by means of NOESY experiments. Dugesin B, arbutin, naringenin and the mixture of oleanolic and ursolic acids were also isolated from this Salvia spp. Full article
Open AccessArticle Transcriptional and Functional Analysis Shows Sodium Houttuyfonate-Mediated Inhibition of Autolysis in Staphylococcus aureus
Molecules 2011, 16(10), 8848-8865; https://doi.org/10.3390/molecules16108848
Received: 13 October 2011 / Accepted: 17 October 2011 / Published: 21 October 2011
Cited by 14 | PDF Full-text (305 KB) | Supplementary Files
Abstract
Sodium houttuyfonate (SH), an addition compound of sodium bisulfite and houttuynin, showed in vitro antibacterial activity against 21 Staphylococcus aureus (S. aureus) strains grown in planktonic cultures. Microarray results showed decreased levels of autolysin atl, sle1, cidA and
[...] Read more.
Sodium houttuyfonate (SH), an addition compound of sodium bisulfite and houttuynin, showed in vitro antibacterial activity against 21 Staphylococcus aureus (S. aureus) strains grown in planktonic cultures. Microarray results showed decreased levels of autolysin atl, sle1, cidA and lytN transcripts in the SH-treated strain as compared to the control strain, consistent with the induction of the autolytic repressors lrgAB and sarA and with the downregulation of the positive regulators agrA and RNAIII. Triton X-100-induced autolysis was significantly decreased by SH in S. aureus ATCC 25923, and quantitative bacteriolytic assays and zymographic analysis demonstrated SH-mediated reduction of extracellular murein hydrolase activity in these cells. Anti-biofilm assay showed that SH is poorly active against S. aureus grown in biofilm cultures, whereas SH diminished the amounts of extracellular DNA (eDNA) of S. aureus in a dose-dependent manner, which suggested that SH may impede biofilm formation by reducing the expression of cidA to inhibit autolysis and eDNA release in the early phase. Some of the microarray results were confirmed by real-time RT-PCR. Full article
Open AccessArticle Components of Rhizome Extract of Cnidium officinale Makino and Their In vitro Biological Effects
Molecules 2011, 16(10), 8833-8847; https://doi.org/10.3390/molecules16108833
Received: 21 September 2011 / Revised: 13 October 2011 / Accepted: 18 October 2011 / Published: 21 October 2011
Cited by 21 | PDF Full-text (954 KB)
Abstract
The anti-inflammatory and anticancer activities of a methanol extract of the rhizome of Cnidium officinale were investigated. Four compounds, namely falcarindiol (1), 6-hydroxy-7-methoxy-dihydroligustilide (2), ligustilidiol (3), and senkyunolide H (4) were isolated from the extract
[...] Read more.
The anti-inflammatory and anticancer activities of a methanol extract of the rhizome of Cnidium officinale were investigated. Four compounds, namely falcarindiol (1), 6-hydroxy-7-methoxy-dihydroligustilide (2), ligustilidiol (3), and senkyunolide H (4) were isolated from the extract of the rhizome of Cnidium officinale and their structures were elucidated by analysis of their spectroscopic data and by comparison with previously reported data. These compounds showed anti-inflammatory activities, measured as inhibition of nitric oxide (NO) release in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells, with IC50 values of 4.31 ± 5.22, 152.95 ± 4.23, 72.78 ± 5.13, and 173.42 ± 3.22 μM, respectively. They also inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA expression induced by LPS. Among these compounds, falcarindiol (1) was found to have anti-proliferative effect against MCF-7 human breast cancer cells by induction of a G0/G1 cell cycle block of the cells, with an IC50 value of 35.67 μM. Typical apoptotic effects were observed by phase contrast microscopy and were also exhibited in fluorescence microscopy with Hoechst 33342 staining. In addition, falcarindiol induced apoptosis through strongly increased mRNA expression of Bax and p53, and slightly reduced Bcl-2 mRNA levels in a dose dependent manner. This study suggested that C. officinale extract and its components would be valuable candidates in therapeutic applications for anti-inflammatory and anti-cancer agents. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessArticle Studies on the Synthesis of DMAP Derivatives by Diastereoselective Ugi Reactions
Molecules 2011, 16(10), 8815-8832; https://doi.org/10.3390/molecules16108815
Received: 17 August 2011 / Revised: 11 October 2011 / Accepted: 12 October 2011 / Published: 20 October 2011
Cited by 15 | PDF Full-text (343 KB)
Abstract
Diastereoselective Ugi reactions of DMAP-based aldehydes with α-amino acids and tert-butyl isocyanide were examined. The reactions of 4-(dimethylamino)-2-pyridine-carboxaldehyde with various α-amino acids afforded 2-substituted DMAP derivatives with low diastereoselectivity. On the contrary, reactions with 4-(dimethylamino)-3-pyridine-carboxaldehyde delivered 3-substituted DMAP derivatives with moderate to
[...] Read more.
Diastereoselective Ugi reactions of DMAP-based aldehydes with α-amino acids and tert-butyl isocyanide were examined. The reactions of 4-(dimethylamino)-2-pyridine-carboxaldehyde with various α-amino acids afforded 2-substituted DMAP derivatives with low diastereoselectivity. On the contrary, reactions with 4-(dimethylamino)-3-pyridine-carboxaldehyde delivered 3-substituted DMAP derivatives with moderate to high diastereoselectivity. The combination of α-amino acid and DMAP-based aldehyde is thus important to achieve high diastereoselectivity. Kinetic resolution of a secondary alcohol using a chiral DMAP derivative obtained through these reactions was also examined. Full article
(This article belongs to the Special Issue Multicomponent Reaction)
Open AccessArticle Microwave-Assisted Improved Synthesis of Oxazolidin-2-ones, Oxazolidine-2-thiones and Thiazolidine-2-thione Chiral Auxiliaries
Molecules 2011, 16(10), 8803-8814; https://doi.org/10.3390/molecules16108803
Received: 13 September 2011 / Revised: 7 October 2011 / Accepted: 18 October 2011 / Published: 20 October 2011
Cited by 9 | PDF Full-text (211 KB)
Abstract
A microwave assisted method for the synthesis of some typical 4-substituted oxazolidinone chiral auxiliaries used in asymmetric synthesis is reported in this work. Under these conditions, treatment of (S)-phenylalaninol, (S)-phenylglycinol, (S)-valinol and (1S, 2R
[...] Read more.
A microwave assisted method for the synthesis of some typical 4-substituted oxazolidinone chiral auxiliaries used in asymmetric synthesis is reported in this work. Under these conditions, treatment of (S)-phenylalaninol, (S)-phenylglycinol, (S)-valinol and (1S, 2R)-norephedrine with ethyl carbonate or carbon disulfide under the appropriate and specific microwave reaction conditions, led to an efficient synthesis of some oxazolidin-2-ones, oxazolidine-2-thiones and thiazolidine-2-thiones. The methodology reported in this paper provides these chiral auxiliaries with improved yields and a remarkable reduction on the reaction times, particularly in the case of thiazolidine-2-thiones, as compared with the conventional methods. All the auxiliaries prepared here show spectroscopic data in full agreement with those previously reported in the literature. Full article
(This article belongs to the Special Issue Microwave Assisted Synthesis)
Figures

Graphical abstract

Open AccessArticle Synthesis, Acidity Constants and Tautomeric Structure of the Diazonium Coupling Products of 2-(Benzylsulfanyl)-7H-purin-6-one in Its Ground and Excited States
Molecules 2011, 16(10), 8788-8802; https://doi.org/10.3390/molecules16108788
Received: 22 September 2011 / Revised: 7 October 2011 / Accepted: 12 October 2011 / Published: 19 October 2011
Cited by 7 | PDF Full-text (276 KB)
Abstract
A series of new 8-arylhydrazono-2-(benzylsulfanyl)-7H-purin-6-ones 6 were synthesized, their electronic absorption spectra in different organic solvents of varying polarities were investigated and their acid dissociation constants in both the ground and excited states were determined spectrophotometrically. The tautomeric structures of such
[...] Read more.
A series of new 8-arylhydrazono-2-(benzylsulfanyl)-7H-purin-6-ones 6 were synthesized, their electronic absorption spectra in different organic solvents of varying polarities were investigated and their acid dissociation constants in both the ground and excited states were determined spectrophotometrically. The tautomeric structures of such products were elucidated by spectral analyses and correlation of their acid dissociation constants with the Hammett equation. The results indicated that the studied compounds 6 exist predominantly in the hydrazone tautomeric form 6A in both the ground and excited states. Full article
(This article belongs to the Special Issue Heterocycles)
Open AccessArticle Divergent Synthesis of Novel Five-Membered Heterocyclic Compounds by Base-Mediated Rearrangement of Acrylamides Derived from a Novel Isocyanide-Based Multicomponent Reaction
Molecules 2011, 16(10), 8775-8787; https://doi.org/10.3390/molecules16108775
Received: 21 September 2011 / Revised: 3 October 2011 / Accepted: 11 October 2011 / Published: 19 October 2011
Cited by 11 | PDF Full-text (237 KB)
Abstract
We have recently reported a novel multicomponent reaction between arylacetic acids and isocyanides, affording α-acyloxyacrylamides through an unusual mechanism. The products of this novel multicomponent reaction can rearrange to five membered heterocyclic compounds when exposed to an alkaline environment. Depending on the reaction
[...] Read more.
We have recently reported a novel multicomponent reaction between arylacetic acids and isocyanides, affording α-acyloxyacrylamides through an unusual mechanism. The products of this novel multicomponent reaction can rearrange to five membered heterocyclic compounds when exposed to an alkaline environment. Depending on the reaction conditions and on the substitution pattern on the substrates, various pyrrolidine derivatives can be selectively obtained. We now wish to report that libraries endowed with skeletal diversity, thus responding to the requirements of Diversity Oriented Synthesis (DOS), can be efficiently prepared in this manner, and phenotypic biological assays have shown interesting properties of some representative compounds. Full article
(This article belongs to the Special Issue Multicomponent Reaction)
Figures

Graphical abstract

Open AccessArticle Triazolobithiophene Light Absorbing Self-Assembled Monolayers: Synthesis and Mass Spectrometry Applications
Molecules 2011, 16(10), 8758-8774; https://doi.org/10.3390/molecules16108758
Received: 20 September 2011 / Revised: 10 October 2011 / Accepted: 17 October 2011 / Published: 19 October 2011
Cited by 3 | PDF Full-text (311 KB) | Supplementary Files
Abstract
The synthesis of five light absorbing triazolobithiophenic thiols, which were utilized for producing self-assembled monolayers (SAMs) on gold surfaces, is presented. The monolayer formation was monitored by cyclic voltammetry, indicating excellent surface coverage. The new triazolobithiophenic compounds exhibited an absorption maximum around 340
[...] Read more.
The synthesis of five light absorbing triazolobithiophenic thiols, which were utilized for producing self-assembled monolayers (SAMs) on gold surfaces, is presented. The monolayer formation was monitored by cyclic voltammetry, indicating excellent surface coverage. The new triazolobithiophenic compounds exhibited an absorption maximum around 340 nm, which is close to the emission wavelength of a standard nitrogen laser. Consequently these compounds could be used to aid ionization in laser desorption mass spectrometry (MS). Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessArticle Facile Synthesis of Functionalized Spiropyrrolizidine Oxindoles via a Three-Component Tandem Cycloaddition Reaction
Molecules 2011, 16(10), 8745-8757; https://doi.org/10.3390/molecules16108745
Received: 26 August 2011 / Revised: 30 September 2011 / Accepted: 3 October 2011 / Published: 19 October 2011
Cited by 16 | PDF Full-text (323 KB) | Supplementary Files
Abstract
An efficient synthesis of functionalized spiropyrrolizidine oxindoles via a three-component tandem cycloaddition has been achieved. This strategy can provide direct and rapid access to spiropyrrolizidine oxindoles in high yields (up to 99%) with excellent diastereoselectivities (up to 99:1 dr). The features of this
[...] Read more.
An efficient synthesis of functionalized spiropyrrolizidine oxindoles via a three-component tandem cycloaddition has been achieved. This strategy can provide direct and rapid access to spiropyrrolizidine oxindoles in high yields (up to 99%) with excellent diastereoselectivities (up to 99:1 dr). The features of this procedure are the following: mild reaction conditions, high yields, high diastereoselectivities, one-pot procedure and operational simplicity. Full article
(This article belongs to the Special Issue Heterocycles)
Open AccessArticle Efficient Microwave-Assisted Synthesis of Ionic Esterified Amino Acids
Molecules 2011, 16(10), 8733-8744; https://doi.org/10.3390/molecules16108733
Received: 16 September 2011 / Revised: 11 October 2011 / Accepted: 14 October 2011 / Published: 19 October 2011
Cited by 8 | PDF Full-text (226 KB)
Abstract
In this work, an efficient microwave-assisted methodology for the esterification of unprotected α-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p
[...] Read more.
In this work, an efficient microwave-assisted methodology for the esterification of unprotected α-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p-TsOH) to afford the pure products after a simple work-up procedure. This procedure can also be extended to the preparation of long and short chain alkyl and benzyl esters. Full article
(This article belongs to the Special Issue Microwave Assisted Synthesis)
Open AccessReview Alkaloids from Marine Ascidians
Molecules 2011, 16(10), 8694-8732; https://doi.org/10.3390/molecules16108694
Received: 16 September 2011 / Revised: 11 October 2011 / Accepted: 14 October 2011 / Published: 19 October 2011
Cited by 28 | PDF Full-text (601 KB)
Abstract
About 300 alkaloid structures isolated from marine ascidians are discussed in term of their occurrence, structural type and reported pharmacological activity. Some major groups (e.g., the lamellarins and the ecteinascidins) are discussed in detail, highlighting their potential as therapeutic agents for the treatment
[...] Read more.
About 300 alkaloid structures isolated from marine ascidians are discussed in term of their occurrence, structural type and reported pharmacological activity. Some major groups (e.g., the lamellarins and the ecteinascidins) are discussed in detail, highlighting their potential as therapeutic agents for the treatment of cancer or viral infections. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessArticle Hepatoprotective Action of Radix Paeoniae Rubra Aqueous Extract against CCl4-Induced Hepatic Damage
Molecules 2011, 16(10), 8684-8693; https://doi.org/10.3390/molecules16108684
Received: 30 August 2011 / Revised: 7 October 2011 / Accepted: 11 October 2011 / Published: 17 October 2011
Cited by 16 | PDF Full-text (183 KB)
Abstract
In the present study the capacity of Radix Paeoniae Rubra aqueous extract (RPRAE) as an antioxidant to protect against carbon tetrachloride (CCl4)-induced oxidative stress and hepatotoxicity in Wistar rats was investigated. Six groups of rats were used. Radix Paeoniae Rubra aqueous
[...] Read more.
In the present study the capacity of Radix Paeoniae Rubra aqueous extract (RPRAE) as an antioxidant to protect against carbon tetrachloride (CCl4)-induced oxidative stress and hepatotoxicity in Wistar rats was investigated. Six groups of rats were used. Radix Paeoniae Rubra aqueous extract (100 or 200 or 300 mg/kg of bw) or bifendate (100 mg/kg of bw) were given daily by gavage to the animals on 28 consecutive days to elucidate the protective effects against CCl4-induced hepatotoxicity. The 20% CCl4/olive oil was gavage of gastric tube twice a week (on the third and seventh days of each week). The animals of normal control group were given only vehicle. The animals of CCl4-treated group were administered with CCl4 twice a week (on the third and seventh days of each week) and with vehicle on rest of the days. The test materials were found effective as hepatoprotective agents, as evidenced by plasma and liver biochemical parameters. Therefore, the results of this study show that Radix Paeoniae Rubra aqueous extract can protect the liver against CCl4-induced oxidative damage in rats, and the hepatoprotective effects might be correlated with its antioxidant and free radical scavenger effects. Full article
Open AccessArticle Synthesis, Metal Ion Complexation and Computational Studies of Thio Oxocrown Ethers
Molecules 2011, 16(10), 8670-8683; https://doi.org/10.3390/molecules16108670
Received: 17 August 2011 / Revised: 29 September 2011 / Accepted: 11 October 2011 / Published: 14 October 2011
Cited by 9 | PDF Full-text (343 KB)
Abstract
The synthesis of some thio-oxocrown ether ligands, B1 (1,4-dithio-12-crown-4), B2 (1,7-dithio-12-crown-4), B3 (1,7-dithio-15-Crown-5), B4 (1,7-dithio-18-crown-6), B5 (1,10-dithio-18-crown-6), B6 (1,10-dithio-21-crown-7), under mild conditions, were reported. The ligands were characterized by FT-IR, 1H NMR and GC-MS spectroscopy. The formation of 1:1 ligand complexes with
[...] Read more.
The synthesis of some thio-oxocrown ether ligands, B1 (1,4-dithio-12-crown-4), B2 (1,7-dithio-12-crown-4), B3 (1,7-dithio-15-Crown-5), B4 (1,7-dithio-18-crown-6), B5 (1,10-dithio-18-crown-6), B6 (1,10-dithio-21-crown-7), under mild conditions, were reported. The ligands were characterized by FT-IR, 1H NMR and GC-MS spectroscopy. The formation of 1:1 ligand complexes with a variety of metal salts (Ag+, Ca+2, K+, Na+, Mg+2, Zn+2 and Fe+2) were investigated by a conductometric method in a 1:1 dioxane–water system at 25 °C, and the complexation constants (Ke = (ΛMAm -Λ) / ((Λ-ΛMaΛbAm) [L]) and free energy (∆Go= - RT lnKe) values are calculated. Details of the specific molecular interactions between the ligands and metals were proposed. We also performed DFT calculations to explain their geometrical properties, charges and frontier molecular orbitals. Full article
(This article belongs to the Special Issue Heterocycles in Supramolecular Chemistry)
Open AccessArticle Mechanistic Studies of the Anti-Ulcerogenic Activity and Acute Toxicity Evaluation of Dichlorido-Copper(II)-4-(2-5-Bromo-benzylideneamino)ethyl) Piperazin-1-ium Phenolate Complex against Ethanol-Induced Gastric Injury in Rats
Molecules 2011, 16(10), 8654-8669; https://doi.org/10.3390/molecules16108654
Received: 7 September 2011 / Revised: 24 September 2011 / Accepted: 27 September 2011 / Published: 14 October 2011
Cited by 17 | PDF Full-text (794 KB)
Abstract
The compound dichlorido-copper(II)-4-(2-5-bromobenzylideneamino)ethyl) piperazin-1-ium phenolate (CuLBS) was synthesized, characterized and screened for acute toxicity and protective activity against ethanol-induced gastric mucosal injury in rats. Gross microscopic lesions, biochemical and immunological parameters and histochemcial staining of glycogen storage were taken into consideration. Oral administration
[...] Read more.
The compound dichlorido-copper(II)-4-(2-5-bromobenzylideneamino)ethyl) piperazin-1-ium phenolate (CuLBS) was synthesized, characterized and screened for acute toxicity and protective activity against ethanol-induced gastric mucosal injury in rats. Gross microscopic lesions, biochemical and immunological parameters and histochemcial staining of glycogen storage were taken into consideration. Oral administration of CuLBS (30 and 60 mg/Kg) for two weeks dose-dependently flattened gastric mucosa, significantly increased gastric mucus and total acidity, compared with control group (P < 0.01). Serum levels of liver enzymes aspartate (AST) and alanine transaminases (ALT), pro-inflammatory (IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokines in the rats exposed to ethanol induced ulceration have been altered. Administration of CuLBS showed considerable (P < 0.05) protection against ulceration by modulating the acute alterations of cytokines AST, ALT and stomach glycogen. Interestingly, CuLBS did not interfere with the natural release of nitric oxide. CuLBS alone (60 mg/Kg) did not exhibit any ulcerogenic effect as assessed using Adami’s scoring scale. An acute toxicity study showed that rats treated with CuLBS (1,000 and 2,000 mg/Kg) manifested no abnormal signs. These findings therefore, suggested that the gastroprotective activity of CuLBS might contribute in modulating the inflammatory cytokine-mediated oxidative damage to gastric mucosa. Full article
(This article belongs to the Section Medicinal Chemistry)
Open AccessArticle Two New Epoxysteroids from Helianthus tuberosus
Molecules 2011, 16(10), 8646-8653; https://doi.org/10.3390/molecules16108646
Received: 5 September 2011 / Revised: 10 October 2011 / Accepted: 11 October 2011 / Published: 13 October 2011
Cited by 4 | PDF Full-text (424 KB)
Abstract
Two new epoxy steroids, 5α,8α-epidioxy-22β,23β-epoxyergosta-6-en-3β-ol (1) and 5α,8α-epidioxy-22α,23α-epoxyergosta-6-en-3β-ol (2), and ten known steroids including (24R)-5α,8
[...] Read more.
Two new epoxy steroids, 5α,8α-epidioxy-22β,23β-epoxyergosta-6-en-3β-ol (1) and 5α,8α-epidioxy-22α,23α-epoxyergosta-6-en-3β-ol (2), and ten known steroids including (24R)-5α,8α-epidioxyergosta-6-en-3β-ol (3), (22E,24R)-5α,8α-epidioxyergosta-6,22-dien-3β-ol (4), (22E,24R)-5α,8α-epidioxyergosta-6,9(11),22-trien-3β-ol (5), β-sitosterol (6), sitost-5-en-3β-ol acetate (7), 7α-hydroxysitosterol (8), schleicheol 2 (9), (24R)-24-ethyl-5α-cholestane-3β,5α,6β-triol (10), 7α-hydroxystigmasterol (11), and stigmasterol (12) were isolated from Helianthus tuberosus grown in Laizhou salinized land of coastal zone of Bohai Sea, China. The structures of these compounds were unambiguously established by 1D, 2D NMR and mass spectroscopic techniques. The new compounds 1 and 2 exhibited weak antibacterial activity and no antifungal activity. Full article
(This article belongs to the Special Issue Steroids)
Open AccessArticle Synthesis, Characterization and Biological Activities of Cu(II), Co(II), Mn(II), Fe(II), and UO2(VI) Complexes with a New Schiff Base Hydrazone: O-Hydroxyacetophenone-7-chloro-4-quinoline Hydrazone
Molecules 2011, 16(10), 8629-8645; https://doi.org/10.3390/molecules16108629
Received: 8 September 2011 / Revised: 30 September 2011 / Accepted: 10 October 2011 / Published: 13 October 2011
Cited by 38 | PDF Full-text (459 KB)
Abstract
The Schiff base hydrazone ligand HL was prepared by the condensation reaction of 7-chloro-4-quinoline with o-hydroxyacetophenone. The ligand behaves either as monobasic bidentate or dibasic tridentate and contain ONN coordination sites. This was accounted for be the presence in the ligand of
[...] Read more.
The Schiff base hydrazone ligand HL was prepared by the condensation reaction of 7-chloro-4-quinoline with o-hydroxyacetophenone. The ligand behaves either as monobasic bidentate or dibasic tridentate and contain ONN coordination sites. This was accounted for be the presence in the ligand of a phenolic azomethine and imine groups. It reacts with Cu(II), Ni(II), Co(II), Mn(II), UO2 (VI) and Fe(II) to form either mono- or binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, NMR, Mass, and UV-Visible spectra. The magnetic moments and electrical conductance of the complexes were also determined. The Co(II), Ni(II) and UO2 (VI) complexes are mononuclear and coordinated to NO sites of two ligand molecules. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, the Ni(II) complex is octahedral while the UO2 (VI) complex has its favoured heptacoordination. The Co(II), Mn(II) complexes and also other Ni(II) and Fe(III) complexes, which were obtained in the presence of Li(OH) as deprotonating agent, are binuclear and coordinated via the NNNO sites of two ligand molecules. All the binuclear complexes have octahedral geometries and their magnetic moments are quite low compared to the calculated value for two metal ions complexes and thus antiferromagnetic interactions between the two adjacent metal ions. The ligand HL and metal complexes were tested against a strain of Gram +ve bacteria (Staphylococcus aureus), Gram −ve bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited high antibacterial activities. Full article
(This article belongs to the Section Organic Chemistry)
Open AccessArticle Synthesis and Pharmacological Activity of Diterpenylnaphthoquinone Derivatives
Molecules 2011, 16(10), 8614-8628; https://doi.org/10.3390/molecules16108614
Received: 13 September 2011 / Revised: 29 September 2011 / Accepted: 30 September 2011 / Published: 13 October 2011
Cited by 9 | PDF Full-text (467 KB)
Abstract
New diterpenylquinones, combining a diterpene diacid and a naphthoquinone, were prepared from junicedric acid and lapachol. The new derivatives were assessed as gastroprotective agents by the HCl-EtOH-induced gastric lesions model in mice as well as for basal cytotoxicity on the following human cell
[...] Read more.
New diterpenylquinones, combining a diterpene diacid and a naphthoquinone, were prepared from junicedric acid and lapachol. The new derivatives were assessed as gastroprotective agents by the HCl-EtOH-induced gastric lesions model in mice as well as for basal cytotoxicity on the following human cell lines: Normal lung fibroblasts (MRC-5), gastric epithelial adenocarcinoma (AGS), and hepatocellular carcinoma (Hep G2). Several of the new compounds were significantly active as antiulcer agents and showed selective cytotoxicity against AGS cells. Full article
(This article belongs to the Section Medicinal Chemistry)
Open AccessArticle The Protective Effects of Silymarin against Doxorubicin-Induced Cardiotoxicity and Hepatotoxicity in Rats
Molecules 2011, 16(10), 8601-8613; https://doi.org/10.3390/molecules16108601
Received: 7 September 2011 / Revised: 5 October 2011 / Accepted: 10 October 2011 / Published: 12 October 2011
Cited by 47 | PDF Full-text (515 KB)
Abstract
Silymarin is a complex of five major compounds, and silibinin is the most biologically active component of the complex. The aim of this study was to investigate, evaluate and confirm the potential cardioprotective and hepatoprotective effects of administration of silymarin, rich in silibinin,
[...] Read more.
Silymarin is a complex of five major compounds, and silibinin is the most biologically active component of the complex. The aim of this study was to investigate, evaluate and confirm the potential cardioprotective and hepatoprotective effects of administration of silymarin, rich in silibinin, at a dose of 60 mg/kg orally for a time-span of 12 days on doxorubicin induced toxicity in male Wistar rats. The in vivo model was used to explore whether silymarin could prevent damage of liver and heart tissue induced by doxorubicin administered every other day at dose of 1.66 mg/kg intraperitoneally for twelve days. In the study the change of body weight, ECG changes, biochemical parameters of oxidative stress, serum activity of alanine and aspartate transaminase, lactate dehydrogenase, creatine kinase and histological preparations of heart and liver samples of treated animals were examined. According to physiological, pharmacological, microscopic and biochemical results, we confirmed that at the examined dose, silymarin exhibits a protective influence on the heart and liver tissue against toxicity induced by doxorubicin. Full article
Open AccessArticle Antioxidant Potential of Polyphenols and Tannins from Burs of Castanea mollissima Blume
Molecules 2011, 16(10), 8590-8600; https://doi.org/10.3390/molecules16108590
Received: 31 August 2011 / Revised: 29 September 2011 / Accepted: 29 September 2011 / Published: 12 October 2011
Cited by 23 | PDF Full-text (525 KB)
Abstract
Spiny burs of Castanea mollissima Blume (Chinese chestnut) are usually discarded as industrial waste during post-harvesting processing. The objective of this study was to establish an extraction and isolation procedure for tannins from chestnut burs, and to assess their potential antioxidant activity. Aqueous
[...] Read more.
Spiny burs of Castanea mollissima Blume (Chinese chestnut) are usually discarded as industrial waste during post-harvesting processing. The objective of this study was to establish an extraction and isolation procedure for tannins from chestnut burs, and to assess their potential antioxidant activity. Aqueous ethanol solution was used as extraction solvent, and HPD 100 macroporous resin column was applied for isolation. The influence of solvent concentration in the extraction and elution process on extraction yield, tannins and polyphenols content, as well as antioxidant potential, including DPPH and ABTS radical scavenging ability, reducing power ability and cellular antioxidant ability were assessed. In both the extraction and isolation process, 50% aqueous ethanol led to superior total tannins and polyphenols content as well as significantly higher antioxidant activity. In addition, the antioxidant activity and the total tannins content in extracts and fractions had a positive linear correlation, and the predominant components responsible for antioxidant activities were characterized as hydrolysable tannins. To the best of our knowledge, this is the first report on the enrichment of tannins from burs of C. mollissim using macroporous resin chromatography, and to assess the cellular antioxidant activity of them. Full article
Open AccessArticle A QM/MM–Based Computational Investigation on the Catalytic Mechanism of Saccharopine Reductase
Molecules 2011, 16(10), 8569-8589; https://doi.org/10.3390/molecules16108569
Received: 5 September 2011 / Revised: 27 September 2011 / Accepted: 30 September 2011 / Published: 12 October 2011
Cited by 6 | PDF Full-text (1423 KB) | Supplementary Files
Abstract
Saccharopine reductase from Magnaporthe grisea, an NADPH-containing enzyme in the α-aminoadipate pathway, catalyses the formation of saccharopine, a precursor to L-lysine, from the substrates glutamate and α-aminoadipate-δ-semialdehyde. Its catalytic mechanism has been investigated using quantum mechanics/molecular mechanics (QM/MM) ONIOM-based approaches. In particular,
[...] Read more.
Saccharopine reductase from Magnaporthe grisea, an NADPH-containing enzyme in the α-aminoadipate pathway, catalyses the formation of saccharopine, a precursor to L-lysine, from the substrates glutamate and α-aminoadipate-δ-semialdehyde. Its catalytic mechanism has been investigated using quantum mechanics/molecular mechanics (QM/MM) ONIOM-based approaches. In particular, the overall catalytic pathway has been elucidated and the effects of electron correlation and the anisotropic polar protein environment have been examined via the use of the ONIOM(HF/6-31G(d):AMBER94) and ONIOM(MP2/6-31G(d)//HF/6-31G(d):AMBER94) methods within the mechanical embedding formulism and ONIOM(MP2/6-31G(d)//HF/6-31G(d):AMBER94) and ONIOM(MP2/6-311G(d,p)//HF/6-31G(d):AMBER94) within the electronic embedding formulism. The results of the present study suggest that saccharopine reductase utilises a substrate-assisted catalytic pathway in which acid/base groups within the cosubstrates themselves facilitate the mechanistically required proton transfers. Thus, the enzyme appears to act most likely by binding the three required reactant molecules glutamate, α-aminoadipate-δ-semialdehyde and NADPH in a manner and polar environment conducive to reaction. Full article
(This article belongs to the Special Issue Enzyme-Catalyzed Reactions)
Figures

Graphical abstract

Open AccessArticle Beneficial Effects of THSG on Acetic Acid-Induced Experimental Colitis: Involvement of Upregulation of PPAR-γ and Inhibition of the Nf-Κb Inflammatory Pathway
Molecules 2011, 16(10), 8552-8568; https://doi.org/10.3390/molecules16108552
Received: 8 August 2011 / Revised: 3 October 2011 / Accepted: 3 October 2011 / Published: 12 October 2011
Cited by 35 | PDF Full-text (868 KB)
Abstract
The polyphenolic compound 2,3,5,4′-tetrahydroxystilbene-2-O-beta-D-glucoside (THSG) has been shown to possess anti-inflammatory effects. Here, we examined the effects of THSG on experimental mice with colitis induced by acetic acid and whether the underlying mechanisms were associated with the PPAR-γ and NF-κB pathways.
[...] Read more.
The polyphenolic compound 2,3,5,4′-tetrahydroxystilbene-2-O-beta-D-glucoside (THSG) has been shown to possess anti-inflammatory effects. Here, we examined the effects of THSG on experimental mice with colitis induced by acetic acid and whether the underlying mechanisms were associated with the PPAR-γ and NF-κB pathways. Mice were randomized into six equal groups: normal, colitis model, THSG (10, 30, 60 mg·kg−1) and mesalazine. The mice were administered 10, 30, 60 mg·kg−1 THSG or 100 mg·kg−1 mesalazine or saline once daily by intragastric administration for 7 days after induction of colitis by acetic acid irrigation. THSG dramatically attenuated acetic acid-induced colon lesions, including reversing the body weight loss and improving histopathological changes. THSG apparently decreased the increase of malondialdehyde (MDA) which is a marker of lipid peroxidation. THSG appears to exert its beneficial effects on acetic acid-induced experimental colitis through upregulation of PPAR-γ mRNA and protein levels and inhibition of the NF-κB pathway, which in turn decreases the protein overexpression of the downstream inflammatory mediators TNF-α, IL-6 and COX-2. The effect of THSG 60 mg·kg−1 on PPAR-γ mRNA expression was higher than that of mesalazine. THSG may thus be a promising new candidate or lead compound for the treatment of IBD. Full article
Open AccessArticle Detection, Quantification, and Microlocalisation of Targets of Pesticides Using Microchannel Plate Autoradiographic Imagers
Molecules 2011, 16(10), 8535-8551; https://doi.org/10.3390/molecules16108535
Received: 1 September 2011 / Revised: 30 September 2011 / Accepted: 30 September 2011 / Published: 11 October 2011
Cited by 10 | PDF Full-text (1495 KB)
Abstract
Organophosphorus (OP) compounds are a diverse chemical group that includes nerve agents and pesticides. They share a common chemical signature that facilitates their binding and adduction of acetylcholinesterase (AChE) within nerve synapses to induce cholinergic toxicity. However, this group diversity results in non-uniform
[...] Read more.
Organophosphorus (OP) compounds are a diverse chemical group that includes nerve agents and pesticides. They share a common chemical signature that facilitates their binding and adduction of acetylcholinesterase (AChE) within nerve synapses to induce cholinergic toxicity. However, this group diversity results in non-uniform binding and inactivation of other secondary protein targets, some of which may be adducted and protein activity influenced, even when only a relatively minor portion of tissue AChE is inhibited. The determination of individual OP protein binding targets has been hampered by the sensitivity of methods of detection and quantification of protein-pesticide adducts. We have overcome this limitation by the employment of a microchannel plate (MCP) autoradiographic detector to monitor a radiolabelled OP tracer compound. We preincubated rat thymus tissue in vitro with the OP pesticides, azamethiphos-oxon, chlorfenvinphos-oxon, chlorpyrifos-oxon, diazinon-oxon, and malaoxon, and then subsequently radiolabelled the free OP binding sites remaining with 3H-diisopropylfluorophosphate (3H-DFP). Proteins adducted by OP pesticides were detected as a reduction in 3H-DFP radiolabelling after protein separation by one dimensional polyacrylamide gel electrophoresis and quantitative digital autoradiography using the MCP imager. Thymus tissue proteins of molecular weights ~28 kDa, 59 kDa, 66 kDa, and 82 kDa displayed responsiveness to adduction by this panel of pesticides. The 59 kDa protein target (previously putatively identified as carboxylesterase I) was only significantly adducted by chlorfenvinphos-oxon (p < 0.001), chlorpyrifos-oxon (p < 0.0001), and diazinon-oxon (p < 0.01), the 66 kDa protein target (previously identified as serum albumin) similarly only adducted by the same three pesticides (p < 0.0001), (p < 0.001), and (p < 0.01), and the 82 kDa protein target (previously identified as acyl peptide hydrolase) only adducted by chlorpyrifos-oxon (p < 0.0001) and diazinon-oxon (p < 0.001), when the average values of tissue AChE inhibition were 30%, 35%, and 32% respectively. The ~28 kDa protein target was shown to be heterogeneous in nature and was resolved to reveal nineteen 3H-DFP radiolabelled protein spots by two dimensional polyacrylamide gel electrophoresis and MCP autoradiography. Some of these 3H-DFP proteins spots were responsive to adduction by preincubation with chlorfenvinphos-oxon. In addition, we exploited the useful spatial resolution of the MCP imager (~70 mm) to determine pesticide micolocalisation in vivo, after animal dosing and autoradiography of brain tissue sections. Collectively, MCP autoradiographic imaging provided a means to detect targets of OP pesticides, quantify their sensitivity of adduction relative to tissue AChE inhibition, and highlighted that these common pesticides exhibit specific binding character to protein targets, and therefore their toxicity will need to be evaluated on an individual compound basis. In addition, MCP autoradiography afforded a useful method of visualisation of the localisation of a small radiolabelled tracer within brain tissue. Full article
(This article belongs to the Special Issue Radiochemistry)
Open AccessReview Anti-Inflammatory Activity of Alkaloids: An Update from 2000 to 2010
Molecules 2011, 16(10), 8515-8534; https://doi.org/10.3390/molecules16108515
Received: 22 July 2011 / Revised: 7 September 2011 / Accepted: 26 September 2011 / Published: 11 October 2011
Cited by 51 | PDF Full-text (413 KB)
Abstract
Many natural substances with proven anti-inflammatory activity have been isolated throughout the years. The aim of this review is to review naturally sourced alkaloids with anti-inflammatory effects reported from 2000 to 2010. The assays were conducted mostly in vivo, and carrageenan-induced pedal
[...] Read more.
Many natural substances with proven anti-inflammatory activity have been isolated throughout the years. The aim of this review is to review naturally sourced alkaloids with anti-inflammatory effects reported from 2000 to 2010. The assays were conducted mostly in vivo, and carrageenan-induced pedal edema was the most used experimental model. Of the 49 alkaloids evaluated, 40 demonstrated anti-inflammatory activity. Of these the most studied type were the isoquinolines. This review was based on NAPRALERT data bank, Web of Science and Chemical Abstracts. In this review, 95 references are cited. Full article
(This article belongs to the Special Issue Alkaloids: Novel Therapeutic Perspectives)
Open AccessArticle Antibacterial Characteristics and Activity of Water-Soluble Chitosan Derivatives Prepared by the Maillard Reaction
Molecules 2011, 16(10), 8504-8514; https://doi.org/10.3390/molecules16108504
Received: 5 September 2011 / Revised: 5 October 2011 / Accepted: 9 October 2011 / Published: 11 October 2011
Cited by 31 | PDF Full-text (419 KB)
Abstract
The antibacterial activity of water-soluble chitosan derivatives prepared by Maillard reactions against Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Escherichia coli, Shigella dysenteriae, and Salmonella typhimurium was examined. Relatively high antibacterial activity against various microorganisms was noted for the
[...] Read more.
The antibacterial activity of water-soluble chitosan derivatives prepared by Maillard reactions against Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Escherichia coli, Shigella dysenteriae, and Salmonella typhimurium was examined. Relatively high antibacterial activity against various microorganisms was noted for the chitosan-glucosamine derivative as compared to the acid-soluble chitosan. In addition, it was found that the susceptibility of the test organisms to the water-soluble chitosan derivative was higher in deionized water than in saline solution. Metal ions were also found to reduce the antibacterial activity of the water-soluble chitosan derivative on S. aureus. The marked increase in glucose level, protein content and lactate dehydrogenase (LDH) activity was observed in the cell supernatant of S. aureus exposed to the water-soluble chitosan derivative in deionized water. The results suggest that the water-soluble chitosan produced by Maillard reaction may be a promising commercial substitute for acid-soluble chitosan. Full article
(This article belongs to the Special Issue Natural Polysaccharides: Chemistry, Bioactivity and Analysis)
Open AccessReview Pharmacological and Biological Antiviral Therapeutics for Cardiac Coxsackievirus Infections
Molecules 2011, 16(10), 8475-8503; https://doi.org/10.3390/molecules16108475
Received: 25 August 2011 / Revised: 29 September 2011 / Accepted: 30 September 2011 / Published: 11 October 2011
Cited by 16 | PDF Full-text (998 KB)
Abstract
Subtype B coxsackieviruses (CVB) represent the most commonly identified infectious agents associated with acute and chronic myocarditis, with CVB3 being the most common variant. Damage to the heart is induced both directly by virally mediated cell destruction and indirectly due to the immune
[...] Read more.
Subtype B coxsackieviruses (CVB) represent the most commonly identified infectious agents associated with acute and chronic myocarditis, with CVB3 being the most common variant. Damage to the heart is induced both directly by virally mediated cell destruction and indirectly due to the immune and autoimmune processes reacting to virus infection. This review addresses antiviral therapeutics for cardiac coxsackievirus infections discovered over the last 25 years. One group represents pharmacologically active low molecular weight substances that inhibit virus uptake by binding to the virus capsid (e.g., pleconaril) or inactivate viral proteins (e.g., NO-metoprolol and ribavirin) or inhibit cellular proteins which are essential for viral replication (e.g., ubiquitination inhibitors). A second important group of substances are interferons. They have antiviral but also immunomodulating activities. The third and most recently discovered group includes biological and cellular therapeutics. Soluble receptor analogues (e.g., sCAR-Fc) bind to the virus capsid and block virus uptake. Small interfering RNAs, short hairpin RNAs and antisense oligonucleotides bind to and led to degradation of the viral RNA genome or cellular RNAs, thereby preventing their translation and viral replication. Most recently mesenchymal stem cell transplantation has been shown to possess antiviral activity in CVB3 infections. Taken together, a number of antiviral therapeutics has been developed for the treatment of myocardial CVB infection in recent years. In addition to low molecular weight inhibitors, biological therapeutics have become promising anti-viral agents. Full article
(This article belongs to the Special Issue Antivirals)
Open AccessArticle An Unexpected Reaction between 5-Hydroxymethylfurfural and Imidazolium-Based Ionic Liquids at High Temperatures
Molecules 2011, 16(10), 8463-8474; https://doi.org/10.3390/molecules16108463
Received: 22 August 2011 / Revised: 14 September 2011 / Accepted: 26 September 2011 / Published: 11 October 2011
Cited by 14 | PDF Full-text (680 KB)
Abstract
A new compound was detected during the production of 5-hydroxymethylfurfural (HMF) from glucose and cellulose in the ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) at high temperatures. Further experiments found that it was derived from the reaction of HMF with [Bmim]Cl. The structure of new
[...] Read more.
A new compound was detected during the production of 5-hydroxymethylfurfural (HMF) from glucose and cellulose in the ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) at high temperatures. Further experiments found that it was derived from the reaction of HMF with [Bmim]Cl. The structure of new compound was established as 1-butyl-2-(5’-methyl-2’-furoyl)imidazole (BMI) based on nuclear magnetic resonance and mass spectrometry analysis, and a possible mechanism for its formation was proposed. Reactions of HMF with other imidazolium-based ionic liquids were performed to check the formation of BMI. Our results provided new insights in terms of side reactions between HMF and imidazolium-based ionic liquids, which should be valuable for designing better processes for the production of furans using biomass and related materials. Full article
(This article belongs to the Section Molecular Diversity)
Figures

Graphical abstract

Open AccessArticle Dissociation of the Disilatricyclic Diallylic Dianion [(C4Ph4SiMe)2]−2 to the Silole Anion [MeSiC4Ph4] by Halide Ion Coordination or Halide Ion Nucleophilic Substitution at the Silicon Atom
Molecules 2011, 16(10), 8451-8462; https://doi.org/10.3390/molecules16108451
Received: 26 August 2011 / Revised: 1 October 2011 / Accepted: 1 October 2011 / Published: 10 October 2011
Cited by 4 | PDF Full-text (381 KB)
Abstract
The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene) [(C4Ph4SiMe)2] (1) with either Li or Na in THF gives the silole anion [MeSiC4Ph4] (2). The head-to-tail dimerization of
[...] Read more.
The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene) [(C4Ph4SiMe)2] (1) with either Li or Na in THF gives the silole anion [MeSiC4Ph4] (2). The head-to-tail dimerization of the silole anion 2 gives crystals of the disilatricyclic diallylic dianion [(C4Ph4SiMe)2]−2 (3). The derivatization of 3 (crystals) with bromoethane (gas) under reduced pressure provides [(MeSiC4Ph4Et)2] (4) quantitatively. The reverse addition of 3 in THF to trimethylsilyl chloride, hydrogen chloride, and bromoethane in THF gives 1-methyl-1-trimethylsilyl-1-silole [Me3SiMeSiC4Ph4] (6), 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C4Ph4H2SiMe-MeSiC4Ph4] (7), and 1-methyl-2,5-diethyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C4Ph4Et2SiMe-MeSiC4Ph4] (8), respectively. The reaction products unambiguously suggest that the silole anion [MeSiC4Ph4] is generated by coordination of the chloride ion at the silicon atom in 3 or by the nucleophilic substitution of either chloride or bromide ion at one of two silicon atoms in 3. The quenching reaction of 3 dissolved in THF with water gives 1,2,3,4-tetraphenyl-2-butene, the disiloxane of 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl [O(MeSiC4Ph4)2] (10) and methyl silicate. Full article
(This article belongs to the Special Issue Organosilicon Chemistry)
Back to Top