Efficient purification of paclitaxel from yews using high-performance displacement chromatography technique.

Paclitaxel was purified using high-performance displacement chromatography (HPDC) technique, but not by the mechanism of HPDC. On small scale, paclitaxel was extracted with methanol from dry needles of Taxus canadensis and was enriched by extracting with chloroform after removing water-soluble hydrophilic components and hexane-soluble hydrophobic components. Then, 93-99% purity of paclitaxel was obtained using the HPDC technique.

Coumestan glycosides from the stem bark of Cylicodiscus gabunensis.

Two new coumestan glycosides, coumestoside C (1) and coumestoside D (2), were isolated from the stem bark of Cylicodiscus gabunensis Harms. Their structures were established by spectroscopic means and chemical transformations as 9-O-alpha-L-rhamnopyranosyl-3-hydroxy-4-(5'-hydroxy-3'-methylbut-2'E-enyl) coumestan (1) and 9-O-beta-D-galactopyranosyl-3-O- prenyl-4-hydroxycoumestan. Coumestoside C exhibited antimicrobial activity against Proteus vulgaris.

One-step purification of palmatine and its derivative dl-tetrahydropalmatine from Enantia chlorantha using high-performance displacement chromatography.

Palmatine and its reduced form, dl-tetrahydropalmatine are a group of isoquinoline alkaloids that have been reported to display a variety of biological and pharmacological activities. Both drugs are hydrophilic and are difficult to be purified by conventional purification methods of natural products. A high-performance displacement chromatography (HPDC) method successfully purified palmatine and its semi-synthetic derivative dl-tetrahydropalmatine from crude extract of the African medicinal plant Enantia chlorantha.

Antimicrobial activity of the methanolic extract, fractions and four flavonoids from the twigs of Dorstenia angusticornis Engl. (Moraceae).

The methanolic extract (DAT), fractions (FRS) and four flavonoids, namely Gancaonin Q (1), Stipulin (2), Angusticornin B (3) and Bartericin A (4), isolated from the twigs of Dorstenia angusticornis (Moraceae), were tested for their in vitro antimicrobial activity. A total of 22 microbial cultures belonging to three Candida species, 6 Gram-positive and 13 Gram-negative bacterial species were used in this study. The inhibition zones (IZ) of the test samples against the pathogens were determined by the Agar Hole Diffusion test while the Liquid dilution method was used to determine their minimal inhibition concentrations (MIC) and their minimal microbicidal concentrations (MMC).

Screening of some medicinal plants from cameroon for beta-lactamase inhibitory activity.

In efforts to find new bioactive beta-lactamase inhibitors, this study investigated 16 Cameroonian plants belonging to 10 families which were evaluated for anti-beta-lactamase activity. The investigation showed that extracts 2, 6, 3 and 5 of the 16 plants investigated presented interesting in vitro beta-lactamase inhibition (over 90%), respectively, of the beta-lactamases TEM-1, OXA-10, IMP-1 and P99. These extracts were from Mammea africana (all beta-lactamases), Garcinia lucida, G.