High-performance thin-layer chromatographic determination of six major ginsenosides in Panax ginseng.

A densitometric determination of six major ginsenosides in Panax ginseng, separated by high-performance thin-layer chromatography (HPTLC), was optimized. Simple extraction and clean-up methods of the target constituents and the development of standardized conditions of chromatoplates with a quaternary-solvents system allowed an efficient saponins recovery from the plant material and their selective separation. After exposure of the chromatograms to thionyl chloride vapors and further heating, stable reaction products of ginsenosides, which showed absorption maxima at lambda=275 nm as well as a fluorescence (lambda(excitation)=366 nm, lambda(emission)=400 nm), allowed the application of a sensitive and reproducible method for their simultaneous determination. The method was validated by spiking the ginseng extracts with pure standards.

[Taxol and related diterpenoids of Taxus sp.: important acquisitions in the treatment of cancer]. / Le taxol et les diterpénoïdes apparentés de Taxus sp: acquisitions importantes dans la chimiothérapie du cancer.

Phytochemical and pharmacological studies on Taxus sp extracts have resulted in the isolation and the identification of several diterpenoids, and the discovery of the potent antitumor activity of taxol. This natural compound displays a unique mechanism of action as it stabilizes microtubules and inhibits their depolymerization into free tubulin. The emergence of taxol from the screening of natural products shows the benefits and the potent interest of these constituents in the search of drugs exhibiting novel mechanisms of action. The most pressing problem in taxol or taxol derivates commercialization is the drug supply. Alternative sources of taxol are now under investigation, mainly the total synthesis of taxol, the hemisynthesis of taxol or of taxotere from 10-deacetylbaccatine III, the in vitro production of taxol by cell or tissue cultures, and the prospection of new natural sources of taxol.

Enzyme-linked immunosorbent assay for the detection and the semi-quantitative determination of taxane diterpenoids related to taxol in Taxus sp. and tissue cultures.

An ELISA-assay for the detection and the semi-quantitative determination of taxane diterpenoids structurally related to taxol found in Taxus sp. has been developed. The antiserum was raised in rabbits using a 2'-succinyltaxol-bovine serum albumin conjugate as immunogen. The working range of the assay was from 1 to 100 ng of taxol. In order to improve the production of taxol, preliminary experiments have been performed on crude extracts of several Taxus sp.; the results indicate that the present immunoassay is an useful tool for the rapid screening of species, varieties or individual plants out of a large population as well as for tissue cultures analysis.