Biomedical subjects

Andrew Marston

Publications and source records attributed to Andrew Marston.

9 recordsLinked to original sources

PubMed2006

Bioactive diterpenes from the fruits of Detarium microcarpum.

A fruit pulp extract of Detarium microcarpum showed inhibition of the growth of the plant pathogenic fungus Cladosporium cucumerinum and of the enzyme acetylcholinesterase, implicated in Alzheimer's disease. Fractionation of this extract led to the isolation of four new clerodane diterpenes, 3,4-epoxyclerodan-13E-en-15-oic acid (1), 5alpha,8alpha(2-oxokolavenic acid) (2), 3,4-dihydroxyclerodan-13E-en-15-oic acid (4), and 3,4-dihydroxyclerodan-13Z-en-15-oic acid (5). Also isolated were 2-oxokolavenic acid (3) and copalic acid (6). Structure elucidation of the compounds was carried out by spectroscopic data interpretation and by the X-ray crystallography of 2 and 4. Three of the new clerodane diterpenes (1, 2, and 5) showed both antifungal activity and inhibition of acetylcholinesterase, and 3 showed a slight inhibition of this enzyme.

Antifungal Agents↗

PubMed2005

Bio-guided isolation of cholinesterase inhibitors from the bulbs of Crinum x powellii.

In a search for potential acetylcholinesterase (AChE) inhibitors, the ethanol extract of the bulbs of Crinum x powellii (Amaryllidaceae) was found to demonstrate a marked inhibition of this enzyme. Using a bio-guided isolation strategy, linoleic acid ethyl ester has been identified as the compound responsible for this inhibition. Three other molecules - the alkaloid hippadine, the glycosylated benzyl alcohol derivative calleryanin and 4'-hydroxy-7-methoxyflavan - were also isolated and characterized for the first time from Crinum x powellii. The structures of these compounds were elucidated by spectrometric methods including EI, D/CI mass spectrometry, (1)H, (13)C and 2D NMR experiments. Linoleic acid was also found to inhibit AChE.

Amaryllidaceae Alkaloids↗

PubMed2005

Methylpyrrole tropane alkaloids from the bark of Erythroxylum vacciniifolium.

Nine new tropane alkaloids substituted by a methylpyrrole moiety were isolated from the bark of Erythroxylum vacciniifolium, a Brazilian endemic plant used in traditional medicine and locally known as catuaba. All compounds were elucidated as tropanediol or -triol alkaloids esterified by at least one 1-methyl-1H-pyrrole-2-carboxylic acid. One of the isolated compounds was identified as a tropane alkaloid N-oxide. Their structures were determined by high-resolution mass spectrometry and multidimensional NMR spectroscopy.

Alkaloids↗

PubMed2004

Screening of non-alkaloidal natural compounds as acetylcholinesterase inhibitors.

Acetylcholinesterase (AChE) inhibitors are currently the only approved therapy for the treatment of Alzheimer's disease, only a limited number of drugs are commercially available. A library of non-alkaloidal natural compounds was investigated. To this end, a convenient microtitre plate method for assaying AChE inhibition, which allows a complete kinetic analysis of AChE inhibitors, was developed. Seven active compounds with Ki values in the micromolar range were identified, six of which were xanthones. This is the first report that a promising potential for AChE inhibition exists in such non-nitrogenous natural compounds. Furthermore, four xanthones among these xanthones had already been described as monoamine oxidase (MAO) inhibitors, making then dual AChE/MAO inhibitors of great interest.

Acetylcholinesterase↗

PubMed2004

Xanthones from Gentiana campestris as new acetylcholinesterase inhibitors.

In order to discover new acetylcholinesterase (AChE) inhibitors, different plant extracts were screened by a previously established TLC bioautographic method. The methanol extract of Gentiana campestris leaves exhibited significant inhibition of AChE activity. A bioactivity-guided fractionation approach was undertaken to isolate the active components. Four xanthones, bellidin, bellidifolin, bellidin 8-O-beta-glucopyranoside (norswertianolin), and bellidifolin 8-O-beta-glucopyranoside (swertianolin), were found to be responsible for the anti-AChE activity effects. Bellidifolin showed similar activity to galanthamine in this enzyme assay.

Acetylcholinesterase↗

PubMed2003

Antifungal diterpenes from Hypoestes serpens (Acanthaceae).

Two new diterpenes, fusicoserpenol A and dolabeserpenoic acid A, with antifungal activity, were isolated from leaves of Hypoestes serpens (Acanthaceae). Their structures were elucidated by means of spectrometric methods including 1D and 2D NMR experiments and MS analysis. X-ray crystallographic analysis confirmed the structure of fusicoserpenol A and established the relative configuration.

Acanthaceae↗

PubMed2003

Tropane alkaloids from the bark of Erythroxylum vacciniifolium.

Eight new tropane alkaloids (1-8) were isolated from the bark of "catuaba", a Brazilian endemic plant Erythroxylum vacciniifolium Martius. Their structures were determined by high-resolution mass spectrometry and multidimensional NMR spectroscopy.

Alkaloids↗

PubMedDate not supplied

Qualitative and quantitative determination of yohimbine in authentic yohimbe bark and in commercial aphrodisiacs by HPLC-UV-API/ MS methods.

The development and validation of a rapid qualitative and quantitative method based on an HPLC-UV-MS technique with atmospheric pressure chemical ionisation and electrospray ionisation for the analysis of yohimbine in a number of commercial aphrodisiac products is reported. HPLC with multiple-stage mass spectrometry experiments allowed the identification of the target compound and increased the selectivity of complex analyses such as those involved with multi-botanical preparations. The precision and the robustness of the method were improved by the use of two internal standards: codeine for UV detection and deuterium-labelled yohimbine for MS detection. Twenty commercial aphrodisiac preparations were analysed and the amount of yohimbine measured and expressed as the maximal dose per day suggested on product labels ranged from 1.32 to 23.16 mg.

Aphrodisiacs↗

PubMedDate not supplied

Labdane diterpenes from Juniperus communis L. berries.

A phytochemical study of the methanol extract of Juniperus communis berries was undertaken. The crude extract was analysed by HPLC-UV and the isolation of the minor compounds was performed by centrifugal partition chromatography. By this means, five diterpenes were isolated, one of which was a new labdane diterpene 15,16-epoxy-12-hydroxy-8(17),13(16),14-labdatrien-19-oic acid. The structures of the isolated compounds were elucidated by spectroscopic methods, including UV, NMR, MS and HR-MS.

Chromatography, Liquid↗