Michele Meyer

Prenylated isoflavanone from the roots of Erythrina sigmoidea

A novel prenylated isoflavanone, sigmoidin I, has been isolated from the roots of Erythrina sigmoidea, in addition to the known isoflavones, corylin and neobavaisoflavone and the known pterocarpan, phaseollidin. Its structure was established as 7,4-dihydroxy-3-methoxy-5-(3-methylbut-2-enyl) isoflavanone by means of spectroscopic analyses and chemical transformations. Neobavaisoflavone displayed antifungal potency in vitro with minimum inhibitory concentrations against Aspergillus fumigatus and Cryptococcus neoformans, of 50 mg ml-1.

Production of taxoids with biological activity by plants and callus culture from selected Taxus genotypes

Twenty seven different yew trees belonging to various genotypes and hybrids have been screened for their capacity to produce significant amounts of taxoids provided with biological activity in the tubulin test. From the three best genotypes selected, Taxus x media Sargentii proved to be able to produce viable calluses from excised roots placed in vitro. Taxoid composition at various times of the in vitro culture was determined and the carcinostatic efficiency of the extracts was established using the KB cell cytotoxicity test. In leaves and calluses, respectively, 0.069 and 0.032% paclitaxel (taxol) contents were found. These contents were significantly higher than those previously reported for other genotypes.

Globulixanthones C, D and E: three prenylated xanthones with antimicrobial properties from the root bark of Symphonia globulifera

Two prenylated xanthone derivatives, named globulixanthones C and D and one bis-xanthone, designated globulixanthone E, have been isolated from the root bark of Symphonia globulifera. The structures of these compounds were elucidated by a detailed spectroscopic analysis. They have been shown to exhibit in vitro significant antimicrobial activity against a range of micro-organisms.

An isoflavanone and a coumestan from Erythrina sigmoidea

Abstract Analysis of the root bark and stem wood of Erythrina sigmoidea led to the isolation of a novel isoflavanone named sigmoidin H and a new coumestan, 4-hydroxycoumestrol, in addition to the known flavonoids abyssinone IV, abyssinone VI, erythrabyssin II, phaseollin, neobavaisoflavone, scandenone and 6,8-diprenylgenistein. The structures of these compounds were established by means of spectroscopic analyses and chemical evidence. Neobavaisoflavone exhibited significant antibacterial potency in vitro against Staphylococcus aureus .

Xanthones from the seeds of Allanblackia monticola and their apoptotic and antiproliferative activities.

Phytochemical investigations of the seeds of ALLANBLACKIA MONTICOLA have led to the isolation and characterization of one new xanthone derivative, named allanxanthone E ( 1), together with seven known compounds, including five xanthones, 1,7-dihydroxy-3-methoxy-2-(3-methylbut-2-enyl)xanthone ( 2), alpha-mangostin ( 3) , garciniafuran ( 4) , allanxanthone C ( 5), and 1,6-dihydroxy-2,4-diprenylxanthone ( 6), and two pentacyclic triterpenes, friedelin and lupeol. The structures of these compounds were established on the basis of one- and two-dimensional NMR homo- and heteronuclear correlation evidence. Some of these compounds were evaluated for their apoptotic and antiproliferative activities against human leukemic B lymphocytes, such as the hairy cell leukemia-derived ESKOL cell line and cells from B-CLL (B-cell chronic lymphocytic leukemia) patients.

5,9,23-Triacontatrienoic Methyl Ester, an Elastase Inhibitor from the Marine Sponge Chondrilla nucula

A polyethylenic fatty ester was isolated from the marine sponge Chondrilla nucula. The structure was elucidated through NMR spectral data and MS analysis as 5,9,23-triacon-tatrienoic methyl ester 1. Compound 1 is an elastase inhibitor [ID50=10 μg/mL (2·10−5M)].