Molecules

107 KiB

Open AccessArticle

Urea- Hydrogen Peroxide (UHP) Oxidation of Thiols to the Corresponding Disulfides Promoted by Maleic Anhydride as Mediator

by Bahador Karami, M. Montazerozohori and M. H. Habibi

Molecules 2005, 10(10), 1358-1363; https://doi.org/10.3390/10101385 - 31 Oct 2005

Cited by 49 | Viewed by 13285

Abstract

Urea-hydrogen peroxide (UHP) was used in the presence of maleic anhydride as mediator in a simple and convenient method for the oxidation in high yield of some thiols to the corresponding disulfides. Peroxymaleic acid formed in situ from the reaction of UHP with [...] Read more.

Urea-hydrogen peroxide (UHP) was used in the presence of maleic anhydride as mediator in a simple and convenient method for the oxidation in high yield of some thiols to the corresponding disulfides. Peroxymaleic acid formed in situ from the reaction of UHP with maleic anhydride has a key role in this oxidation. Performance of the reaction in various solvents showed that methanol was the solvent of choice at 0 oC. The products were isolated by simple filtration on silica gel. Full article

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125 KiB

Open AccessArticle

A Novel Synthesis of (E)-3-Methylthio-3-Substituted Arylamino-2-Cyanoacrylates under Microwave Irradiation

by Guiping Ouyang, Baoan Song, Huiping Zhang, Song Yang, Linhong Jin, Qianzhu Li and Deyu Hu

Molecules 2005, 10(10), 1351-1357; https://doi.org/10.3390/10101351 - 31 Oct 2005

Cited by 12 | Viewed by 9660

Abstract

A facile synthesis of 3-methylthio-3-arylamino-2-cyanoacrylates from 3,3-dimethylthioacrylate and aromatic amines or amino pyridines has been achieved in moderate to high yields (64.0% ~ 93.5%) in 30 minutes at 50°C under microwave irradiation. This method is very simple and the reaction conditions are mild, [...] Read more.

A facile synthesis of 3-methylthio-3-arylamino-2-cyanoacrylates from 3,3-dimethylthioacrylate and aromatic amines or amino pyridines has been achieved in moderate to high yields (64.0% ~ 93.5%) in 30 minutes at 50°C under microwave irradiation. This method is very simple and the reaction conditions are mild, environmentally friendly and more importantly, quick. In the 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) test, some of the title compounds were found to possess good antiproliferation activity towards PC3 cells. Full article

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173 KiB

Open AccessArticle

Formation of New Alkynyl(phenyl)iodonium Salts and Their Use in the Synthesis of Phenylsulfonyl Indenes and Acetylenes

by A. Koumbis, C. Kyzas, A. Savva and A. Varvoglis

Molecules 2005, 10(10), 1340-1350; https://doi.org/10.3390/10101340 - 31 Oct 2005

Cited by 20 | Viewed by 8939

Abstract

The preparation of phenylsulfonyl indene derivatives and phenylsulfonyl- acetylenes from readily available alkynyl(phenyl)iodonium tetrafluoroborates and triflates was investigated using phenylsulfinate as nucleophile. Full article

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105 KiB

Open AccessArticle

Diastereoselective Spiroannulation of Phenolic Substrates: Synthesis of (±)-2-tert-Butyl-6-methoxy-1-oxaspiro[4,5]deca-6,9-diene-8-one

by G. Plourde and N. English

Molecules 2005, 10(10), 1335-1339; https://doi.org/10.3390/10101335 - 31 Oct 2005

Cited by 5 | Viewed by 6348

Abstract

The synthesis of a new spiroether is described. The title compound is obtained as a diastereomeric mixture in 45% yield. Full article

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118 KiB

Open AccessArticle

Facile Preparation of Peracetates and Per-3-bromobenzoates of α-Mono- and Disaccharides

by Zerong Wang, Mahfuza Matin and Samia Sheikh

Molecules 2005, 10(10), 1325-1334; https://doi.org/10.3390/10101325 - 31 Oct 2005

Cited by 14 | Viewed by 10846

Abstract

A simple and convenient method for the preparation of fully acetylated and (3- bromo)benzoylated α-monosaccharides and disaccharides through vigorous mechanical mixing of solid reactants on a high speed shaker is described. Using this technique a variety of α-acylated sugars are prepared, including penta-O-acetyl-α-D-galactopyranose, [...] Read more.

A simple and convenient method for the preparation of fully acetylated and (3- bromo)benzoylated α-monosaccharides and disaccharides through vigorous mechanical mixing of solid reactants on a high speed shaker is described. Using this technique a variety of α-acylated sugars are prepared, including penta-O-acetyl-α-D-galactopyranose, penta-O- acetyl-α-D-glucopyranose, penta-O-acetyl-α-D-mannopyranose, octa-O-acetyl-α-lactose, penta-O-(3-bromo)benzoyl-α-D-galactopyranose, penta-O-(3-bromo)benzoyl-α-D-gluco- pyranose, penta-O-(3-bromo)benzoyl-α-D-mannopyranose, and octa-O-(3-bromo)benzoyl- α-lactose. Full article

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52 KiB

Open AccessArticle

Synthesis of New Potentially Bioactive Bicyclic 2-Pyridones

by Maxime D. Crozet, Pascal George, Michel P. Crozet and Patrice Vanelle

Molecules 2005, 10(10), 1318-1324; https://doi.org/10.3390/10101318 - 31 Oct 2005

Cited by 13 | Viewed by 8679

Abstract

Three convenient methods of reduction of the nitro group of 5-nitroimidazoles and 5-nitrothiazole that bear a diethylmethylene malonate group in an ortho-like position with respect to the nitro group and cyclization of the resulting amino derivatives are reported. These reactions afforded the target [...] Read more.

Three convenient methods of reduction of the nitro group of 5-nitroimidazoles and 5-nitrothiazole that bear a diethylmethylene malonate group in an ortho-like position with respect to the nitro group and cyclization of the resulting amino derivatives are reported. These reactions afforded the target bicyclic 2-pyridones in good to excellent yields. Full article

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229 KiB

Open AccessArticle

Eco-friendly Oxidative Iodination of Various Arenes with Sodium Percarbonate as the Oxidant†

by Agnieszka Zielinska and Lech Skulski

Molecules 2005, 10(10), 1307-1317; https://doi.org/10.3390/10101307 - 31 Oct 2005

Cited by 26 | Viewed by 11148

Abstract

Six easy laboratory procedures are presented for the oxidative iodination ofvarious aromatics, mostly arenes, with either molecular iodine or potassium iodide (usedas the sources of iodinating species, I or I³ ), in the presence of sodium percarbonate(SPC), a stable, cheap, easy to [...] Read more.

Six easy laboratory procedures are presented for the oxidative iodination ofvarious aromatics, mostly arenes, with either molecular iodine or potassium iodide (usedas the sources of iodinating species, I or I³ ), in the presence of sodium percarbonate(SPC), a stable, cheap, easy to handle, and eco-friendly commercial oxidant. Full article

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139 KiB

Open AccessArticle

Pyrazolo[4,3-e][1,2,4]triazines: Purine Analogues with Electronic Absorption in the Visible Region

by Mariusz Mojzych, Andrzej Rykowski and Jacek Wierzchowski

Molecules 2005, 10(10), 1298-1306; https://doi.org/10.3390/10101298 - 31 Oct 2005

Cited by 17 | Viewed by 7939

Abstract

Synthesis of several pryrazolo[4,3-e][1,2,4]-triazines is described. Theabsorption spectrum of some 5-substituted derivatives was found to extend to the visibleregion. These compounds were found to inhibit some enzymes of purine metabolism, likexanthine oxidase or bacterial purine-nucleoside phosphorylase with Ki values in the 10^-3 [...] Read more.

Synthesis of several pryrazolo[4,3-e][1,2,4]-triazines is described. Theabsorption spectrum of some 5-substituted derivatives was found to extend to the visibleregion. These compounds were found to inhibit some enzymes of purine metabolism, likexanthine oxidase or bacterial purine-nucleoside phosphorylase with Ki values in the 10^-3 –10^-5 M range. Full article

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67 KiB

Open AccessArticle

9-Hydroxyfurodysinin-O-ethyl Lactone: A New Sesquiterpene Isolated from the Tropical Marine Sponge Dysidea arenaria

by A. Piggott and P. Karuso

Molecules 2005, 10(10), 1292-1297; https://doi.org/10.3390/10101292 - 31 Oct 2005

Cited by 11 | Viewed by 8740

Abstract

A new sesquiterpene, 9-hydroxyfurodysinin-O-ethyl lactone, has been isolated from a New Caledonian Dysidea arenaria, along with three known compounds. The possible incorporation of the ethyl ether from the extraction solvent is discussed. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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62 KiB

Open AccessArticle

Isolation and Structure Elucidation of a Novel Yellow Pigment from the Marine Bacterium Pseudoalteromonas tunicata

by A. Franks, P. Haywood, C. Holmström, S. Egan, S. Kjelleberg and N. Kumar

Molecules 2005, 10(10), 1286-1291; https://doi.org/10.3390/10101286 - 31 Oct 2005

Cited by 93 | Viewed by 13369

Abstract

The marine environment is a major source for many novel natural compounds. A new yellow pigment has been isolated from the marine bacterium P. tunicata and identified as a new member of the tambjamine class of compounds. The structural identification was achieved by [...] Read more.

The marine environment is a major source for many novel natural compounds. A new yellow pigment has been isolated from the marine bacterium P. tunicata and identified as a new member of the tambjamine class of compounds. The structural identification was achieved by a combination of 1D and 2D-NMR spectroscopy and high resolution mass spectrometry data. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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163 KiB

Open AccessArticle

Modulation of macrophage immune responses by Echinacea

by L. Stevenson, A. Matthias, L. Banbury, K. Penman, K. Bone, D. Leach and R. Lehmann

Molecules 2005, 10(10), 1279-1285; https://doi.org/10.3390/10101279 - 31 Oct 2005

Cited by 29 | Viewed by 15131

Abstract

Echinacea preparations are widely used herbal medicines for the prevention and treatment of colds and minor infections. There is little evidence for the individual components in Echinacea that contribute to immune regulatory activity. Activity of an ethanolic Echinacea extract and several constituents, including [...] Read more.

Echinacea preparations are widely used herbal medicines for the prevention and treatment of colds and minor infections. There is little evidence for the individual components in Echinacea that contribute to immune regulatory activity. Activity of an ethanolic Echinacea extract and several constituents, including cichoric acid, have been examined using three in vitro measures of macrophage immune function – NF-κB, TNF- α and nitric oxide (NO). In cultured macrophages, all components except the monoene alkylamide (AA1) decreased lipopolysaccharide (LPS) stimulated NF-κB levels. 0.2 μg/ml cichoric acid and 2.0μg/mL Echinacea Premium Liquid (EPL) and EPL alkylamide fraction (EPL AA) were found to significantly decrease TNF-α production under LPS stimulated conditions in macrophages. In macrophages, only the alkylamide mixture isolated from the ethanolic Echinacea extract decreased LPS stimulated NO production. In this study, the mixture of alkylamides in the Echinacea ethanolic liquid extract did not respond in the same manner in the assays as the individual alkylamides investigated. While cichoric acid has been shown to affect NF-κB, TNF-α and NO levels, it is unlikely to be relevant in the Echinacea alterations of the immune response in vivo due to its non- bioavailability – i.e. no demonstrated absorption across the intestinal barrier and no detectable levels in plasma. These results demonstrate that Echinacea is an effective modulator of macrophage immune responses in vitro. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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74 KiB

Open AccessArticle

Towards a Synthesis of Naphthalene Derived Natural Products

by M. McCulloch and R. Barrow

Molecules 2005, 10(10), 1272-1278; https://doi.org/10.3390/10101272 - 31 Oct 2005

Cited by 9 | Viewed by 10937

Abstract

Dieckmann-type cyclization reactions have been employed in the synthesis of the alkyl substituted naphthoquinone 11 and the naphthalenes 10 and 12. Various conditions for the benzylic oxidation of these compounds have been investigated with a view towards the synthesis of some naphthalene based [...] Read more.

Dieckmann-type cyclization reactions have been employed in the synthesis of the alkyl substituted naphthoquinone 11 and the naphthalenes 10 and 12. Various conditions for the benzylic oxidation of these compounds have been investigated with a view towards the synthesis of some naphthalene based natural products. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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413 KiB

Open AccessArticle

Theoretical Study of Molecular Determinants Involved in Signal Binding to the TraR Protein of Agrobacterium tumefaciens

by W. Goh, S. Rice and N. Kumar

Molecules 2005, 10(10), 1263-1271; https://doi.org/10.3390/10101263 - 31 Oct 2005

Cited by 7 | Viewed by 11183

Abstract

N-acylated homoserine lactone (AHL) mediated cell-cell communication in bacteria is dependent on the recognition of the cognate signal by its receptor. This interaction allows the receptor-ligand complex to act as a transcriptional activator, controlling the expression of a range of bacterial phenotypes, including [...] Read more.

N-acylated homoserine lactone (AHL) mediated cell-cell communication in bacteria is dependent on the recognition of the cognate signal by its receptor. This interaction allows the receptor-ligand complex to act as a transcriptional activator, controlling the expression of a range of bacterial phenotypes, including virulence factor expression and biofilm formation. One approach to determine the key features of signal- binding is to model the intermolecular interactions between the receptor and ligand using computational-based modeling software (LigandFit). In this communication, we have modeled the crystal structure of the AHL receptor protein TraR and its AHL signal N-(3- oxooctanoyl)-homoserine lactone from Agrobacterium tumefaciens and compared it to the previously reported antagonist behaviour of a number of AHL analogues, in an attempt to determine structural constraints for ligand binding. We conclude that (i) a common conformation of the AHL in the hydrophobic and hydrophilic region exists for ligand-binding, (ii) a tail chain length threshold of 8 carbons is most favourable for ligand-binding affinity, (iii) the positive correlation in the docking studies could be used a virtual screening tool. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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218 KiB

Open AccessReview

25 Years of Natural Product R&D with New South Wales Agriculture

by I. Southwell

Molecules 2005, 10(10), 1232-1241; https://doi.org/10.3390/10101232 - 31 Oct 2005

Cited by 3 | Viewed by 11590

Abstract

Following recent NSW Government restructuring, the Department of Agriculture now exists in a composite form along with Forestry, Fisheries and Minerals in the new NSW Department of Primary Industries. This paper outlines some of the highlights of secondary metabolite R&D accomplished in the [...] Read more.

Following recent NSW Government restructuring, the Department of Agriculture now exists in a composite form along with Forestry, Fisheries and Minerals in the new NSW Department of Primary Industries. This paper outlines some of the highlights of secondary metabolite R&D accomplished in the 25 years since the essential oil research unit was transferred from the Museum of Applied Arts & Sciences, Sydney to NSW Agriculture’s Wollongbar Agricultural Institute on the NSW north coast. The essential oil survey was continued, typing the Australian flora as a suitable source of isolates such as myrtenal (Astartea), myrtenol (Agonis), methyl chavicol (Ochrosperma), α-phellandren-8-ol (Prostanthera), methyl myrtenate (Darwinia), methyl geranate (Darwinia), kessane (Acacia), cis-dihydroagarofuran (Prosthanthera), protoanemonin (Clematis), isoamyl isovalerate (Micromyrtus), methyl cinnamate (Eucalyptus) and bornyl acetate (Boronia). Many of these components are used, or have potential use in the fragrance, flavour, medicinal plant or insect attraction fields. Two weeds toxic to livestock in the Central West of the State are also harvested commercially as medicinal plants. Measurement of hypericin concentrations in the various plant parts of St John’s Wort (Hypericum perforatum) over two seasons has shown that the weed can be effectively managed by grazing sheep during the winter months when toxin levels are low. Syntheses of β-carbolines tribulusterine and perlolyrine have shown that the former alkaloid was misidentified in the literature and hence not the toxic principle responsible for Tribulus staggers in sheep. Poor quality (high 1,8-cineole – low terpinen-4-ol) oil bearing tea tree (Melaleuca alternifolia) plantations have been established to the detriment of many a tea tree farmer. Analytical methods developed to check leaf quality at an early age indicated precursor sabinene constituents that convert to the active terpinen-4-ol both as the leaf matures or as the precursors are distilled for oil production. Tea tree’s major insect pest, pyrgo beetle (Paropsisterna tigrina), was seen to selectively metabolize only 1,8-cineole from it’s monoterpenoid-rich diet. Characterization of these and other metabolites from myrtaceous herbivores showed a species specific production of predominately ring hydroxylated products, some of which were attractive when bioassayed against adult beetles. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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30 KiB

Open AccessEditorial

2004 RACI One-day Natural Products Group Symposium

by P. Karuso

Molecules 2005, 10(10), 1229-1231; https://doi.org/10.3390/10101229 - 31 Oct 2005

Viewed by 4178

Abstract

This special issue of Molecules is dedicated to the Royal Australian Chemical Institute’s Natural Products group.[...] Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

135 KiB

Open AccessArticle

An Ethnopharmacological Study of Medicinal Plants in New South Wales

by N. Brouwer, Q. Liu, D. Harrington, J. Kohen, S. Vemulpad, J. Jamie, M. Randall and D. Randall

Molecules 2005, 10(10), 1252-1262; https://doi.org/10.3390/10101252 - 30 Oct 2005

Cited by 21 | Viewed by 13995

Abstract

The Australian Aboriginal people have used plants as medicine and food for thousands of years, however, this traditional knowledge is documented only to a limited extent, and is in danger of being lost. The Indigenous Bioresources Research Group (IBRG) aims to help Australian [...] Read more.

The Australian Aboriginal people have used plants as medicine and food for thousands of years, however, this traditional knowledge is documented only to a limited extent, and is in danger of being lost. The Indigenous Bioresources Research Group (IBRG) aims to help Australian Aboriginal communities to preserve their customary medicinal knowledge, and to provide information that can be used for their cultural or educational purposes, as well as for scientific advancement. This work is undertaken in close collaboration with Australian Aboriginal communities in New South Wales. The project is multidisciplinary, combining an ethnobotanical and an ethnopharmacological approach, which includes biological and chemical investigations, as well as developing best practices for protecting traditional knowledge. This paper describes the general strategy of the project as well as methods used in the ethnopharmacological study. Ethnobotanical databases are set up for each participating community. Plant material is collected, extracted, and active compounds are isolated using a bioassay-guided fractionation approach. All extracts and compounds are tested for biological activity in antimicrobial assays (disc diffusion, resazurin, fluorescein diacetate), neurological assays or anti-inflammatory assays, depending on their traditional use. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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102 KiB

Open AccessArticle

Bioavailability of Echinacea Constituents: Caco-2 Monolayers and Pharmacokinetics of the Alkylamides and Caffeic Acid Conjugates

by A. Matthias, K. Penman, N. Matovic, K. Bone, J. De Voss and R. Lehmann

Molecules 2005, 10(10), 1242-1251; https://doi.org/10.3390/10101242 - 30 Oct 2005

Cited by 20 | Viewed by 12352

Abstract

Many studies have been done over the years to assess the effectiveness of Echinacea as an immunomodulator. We have assessed the potential bioavailability of alkyl- amides and caffeic acid conjugates using Caco-2 monolayers and compared it to their actual bioavailability in a Phase [...] Read more.

Many studies have been done over the years to assess the effectiveness of Echinacea as an immunomodulator. We have assessed the potential bioavailability of alkyl- amides and caffeic acid conjugates using Caco-2 monolayers and compared it to their actual bioavailability in a Phase I clinical trial. The caffeic acid conjugates permeated poorly through the Caco-2 monolayers. Alkylamides were found to diffuse rapidly through Caco-2 monolayers. Differences in diffusion rates for each alkylamide correlated to structural variations, with saturation and N-terminal methylation contributing to decreases in diffusion rates. Alkylamide diffusion is not affected by the presence of other constituents and the results for a synthetic alkylamide were in line with those for alkylamides found in an ethanolic Echinacea preparation. We examined plasma from healthy volunteers for 12 hours after ingestion of Echinacea tablets manufactured from an ethanolic liquid extract. Caffeic acid conjugates could not be identified in any plasma sample at any time after tablet ingestion. Alkylamides were detected in plasma 20 minutes after tablet ingestion and for each alkylamide, pharmacokinetic profiles were devised. The data are consistent with the dosing regimen of one tablet three times daily and supports their usage as the primary markers for quality Echinacea preparations. Full article

(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

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Molecules, Volume 10, Issue 10 (October 2005) – 17 articles , Pages 1229-1363

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