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

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Article
Urea- Hydrogen Peroxide (UHP) Oxidation of Thiols to the Corresponding Disulfides Promoted by Maleic Anhydride as Mediator
Molecules 2005, 10(10), 1358-1363; https://doi.org/10.3390/10101385 - 31 Oct 2005
Cited by 43 | Viewed by 8936
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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Article
A Novel Synthesis of (E)-3-Methylthio-3-Substituted Arylamino-2-Cyanoacrylates under Microwave Irradiation
Molecules 2005, 10(10), 1351-1357; https://doi.org/10.3390/10101351 - 31 Oct 2005
Cited by 9 | Viewed by 7316
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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Article
Formation of New Alkynyl(phenyl)iodonium Salts and Their Use in the Synthesis of Phenylsulfonyl Indenes and Acetylenes
Molecules 2005, 10(10), 1340-1350; https://doi.org/10.3390/10101340 - 31 Oct 2005
Cited by 19 | Viewed by 6370
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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Article
Diastereoselective Spiroannulation of Phenolic Substrates: Synthesis of (±)-2-tert-Butyl-6-methoxy-1-oxaspiro[4,5]deca-6,9-diene-8-one
Molecules 2005, 10(10), 1335-1339; https://doi.org/10.3390/10101335 - 31 Oct 2005
Cited by 4 | Viewed by 4528
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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Article
Facile Preparation of Peracetates and Per-3-bromobenzoates of α-Mono- and Disaccharides
Molecules 2005, 10(10), 1325-1334; https://doi.org/10.3390/10101325 - 31 Oct 2005
Cited by 11 | Viewed by 6617
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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Article
Synthesis of New Potentially Bioactive Bicyclic 2-Pyridones
Molecules 2005, 10(10), 1318-1324; https://doi.org/10.3390/10101318 - 31 Oct 2005
Cited by 13 | Viewed by 6514
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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Article
Eco-friendly Oxidative Iodination of Various Arenes with Sodium Percarbonate as the Oxidant†
Molecules 2005, 10(10), 1307-1317; https://doi.org/10.3390/10101307 - 31 Oct 2005
Cited by 21 | Viewed by 7585
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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Article
Pyrazolo[4,3-e][1,2,4]triazines: Purine Analogues with Electronic Absorption in the Visible Region
Molecules 2005, 10(10), 1298-1306; https://doi.org/10.3390/10101298 - 31 Oct 2005
Cited by 15 | Viewed by 5677
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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Article
9-Hydroxyfurodysinin-O-ethyl Lactone: A New Sesquiterpene Isolated from the Tropical Marine Sponge Dysidea arenaria
Molecules 2005, 10(10), 1292-1297; https://doi.org/10.3390/10101292 - 31 Oct 2005
Cited by 11 | Viewed by 6525
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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Article
Isolation and Structure Elucidation of a Novel Yellow Pigment from the Marine Bacterium Pseudoalteromonas tunicata
Molecules 2005, 10(10), 1286-1291; https://doi.org/10.3390/10101286 - 31 Oct 2005
Cited by 71 | Viewed by 8966
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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Article
Modulation of macrophage immune responses by Echinacea
Molecules 2005, 10(10), 1279-1285; https://doi.org/10.3390/10101279 - 31 Oct 2005
Cited by 29 | Viewed by 12130
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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Article
Towards a Synthesis of Naphthalene Derived Natural Products
Molecules 2005, 10(10), 1272-1278; https://doi.org/10.3390/10101272 - 31 Oct 2005
Cited by 8 | Viewed by 8232
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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Article
Theoretical Study of Molecular Determinants Involved in Signal Binding to the TraR Protein of Agrobacterium tumefaciens
Molecules 2005, 10(10), 1263-1271; https://doi.org/10.3390/10101263 - 31 Oct 2005
Cited by 7 | Viewed by 8766
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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Review
25 Years of Natural Product R&D with New South Wales Agriculture
Molecules 2005, 10(10), 1232-1241; https://doi.org/10.3390/10101232 - 31 Oct 2005
Cited by 3 | Viewed by 9791
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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Editorial
2004 RACI One-day Natural Products Group Symposium
Molecules 2005, 10(10), 1229-1231; https://doi.org/10.3390/10101229 - 31 Oct 2005
Viewed by 2824
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)
Article
An Ethnopharmacological Study of Medicinal Plants in New South Wales
Molecules 2005, 10(10), 1252-1262; https://doi.org/10.3390/10101252 - 30 Oct 2005
Cited by 17 | Viewed by 11051
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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Article
Bioavailability of Echinacea Constituents: Caco-2 Monolayers and Pharmacokinetics of the Alkylamides and Caffeic Acid Conjugates
Molecules 2005, 10(10), 1242-1251; https://doi.org/10.3390/10101242 - 30 Oct 2005
Cited by 18 | Viewed by 8657
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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