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Special Issue "2004 RACI One-day Natural Products Group Symposium"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (31 March 2005)

Published Papers (9 papers)

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Displaying articles 1-9
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Editorial

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Open AccessEditorial 2004 RACI One-day Natural Products Group Symposium
Molecules 2005, 10(10), 1229-1231; doi:10.3390/10101229
Received: 28 July 2005 / Published: 31 October 2005
PDF Full-text (30 KB)
(This article belongs to the Special Issue 2004 RACI One-day Natural Products Group Symposium)

Research

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Open AccessArticle Theoretical Study of Molecular Determinants Involved in Signal Binding to the TraR Protein of Agrobacterium tumefaciens
Molecules 2005, 10(10), 1263-1271; doi:10.3390/10101263
Received: 1 December 2004 / Accepted: 20 April 2005 / Published: 31 October 2005
Cited by 3 | PDF Full-text (413 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Towards a Synthesis of Naphthalene Derived Natural Products
Molecules 2005, 10(10), 1272-1278; doi:10.3390/10101272
Received: 3 December 2004 / Accepted: 28 April 2005 / Published: 31 October 2005
Cited by 3 | PDF Full-text (74 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Modulation of macrophage immune responses by Echinacea
Molecules 2005, 10(10), 1279-1285; doi:10.3390/10101279
Received: 3 December 2004 / Accepted: 26 May 2005 / Published: 31 October 2005
Cited by 17 | PDF Full-text (163 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle Isolation and Structure Elucidation of a Novel Yellow Pigment from the Marine Bacterium Pseudoalteromonas tunicata
Molecules 2005, 10(10), 1286-1291; doi:10.3390/10101286
Received: 12 December 2004 / Revised: 21 April 2005 / Accepted: 4 May 2005 / Published: 31 October 2005
Cited by 45 | PDF Full-text (62 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle 9-Hydroxyfurodysinin-O-ethyl Lactone: A New Sesquiterpene Isolated from the Tropical Marine Sponge Dysidea arenaria
Molecules 2005, 10(10), 1292-1297; doi:10.3390/10101292
Received: 28 March 2005 / Accepted: 2 May 2005 / Published: 31 October 2005
Cited by 9 | PDF Full-text (67 KB) | HTML Full-text | XML Full-text
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)
Open AccessArticle Bioavailability of Echinacea Constituents: Caco-2 Monolayers and Pharmacokinetics of the Alkylamides and Caffeic Acid Conjugates
Molecules 2005, 10(10), 1242-1251; doi:10.3390/10101242
Received: 26 November 2004 / Accepted: 18 March 2005 / Published: 30 October 2005
Cited by 14 | PDF Full-text (102 KB) | HTML Full-text | XML Full-text
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
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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)
Open AccessArticle An Ethnopharmacological Study of Medicinal Plants in New South Wales
Molecules 2005, 10(10), 1252-1262; doi:10.3390/10101252
Received: 1 December 2004 / Accepted: 15 April 2005 / Published: 30 October 2005
Cited by 9 | PDF Full-text (135 KB) | HTML Full-text | XML Full-text
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
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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)

Review

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Open AccessReview 25 Years of Natural Product R&D with New South Wales Agriculture
Molecules 2005, 10(10), 1232-1241; doi:10.3390/10101232
Received: 7 March 2005 / Accepted: 30 May 2005 / Published: 31 October 2005
PDF Full-text (218 KB)
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
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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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