Cytotoxic natural products from thai plants: a recent study.

Natural products will continue to be the most prolific source of bioactive compounds. Natural products exhibiting antitumor activity continue to be the subject of extensive research aimed at the development of drugs for the treatment of different human tumors. It is generally accepted that natural products offer a diversity and complexity of structure unmatched by even the most active imaginations of synthetic organic chemists. This paper reviews the research of selected Thai plants for the discovery of therapeutic agents. Attention will be focused on our recent research on Thai plants that possess cytotoxic properties. Synthetic modification and reaction of some of these compounds aimed at enhancing their potency will also be presented.

Chemical investigation of mammea siamensis.

A new 4-alkylcoumarin, mammea B/AC cyclo D ( 1 ), together with a 4-phenylcoumarin, mammea A/AC cyclo D ( 2 ), were isolated from the hexane extract of the dried flower of Mammea siamensis . Their structures were determined on the basis of spectroscopic evidence.

Reinvestigation of derris reticulata.

The novel compound 1'''-hydroxy-2''',3'''-epoxylupinifolin ( 1 ), together with three known prenylated flavanones were identified from the stem of Derris reticulata during our reinvestigation of the plant. The structures were determined by spectroscopic methods including detailed study of NMR spectral data (DEPT, 2D-COSY, HMQC and HMBC) as well as by chemical derivatizations.

New sesquiterpene lactones with antibacterial activity from Vernonia fastigiata.

Sesquiterpene lactones 1-5 were isolated for the first time from the ethyl acetate of Vernonia fastigiata (Asteraceae). Compounds 3, 4 and 5 are new, compounds 1 and 2 have been found earlier in other Vernonia species but not in V. fastigiata.

Cyanogenic and non-cyanogenic glycosides from Manihot esculenta.

In addition to lotaustralin and linamarin, a novel cyanogenic glycoside, 2-((6-O-(beta-D-apiofuranosyl)-beta-D-glucopyranosyl)oxy)-2-met hylbutanenitrile , two novel non-cyanogenic glycosides, (2S)-((6-O-(beta-D-apiofuranosyl)-beta-D- glucopyranosyl)oxy)butane and 2-((6-O-(beta-D-apiofuranosyl)-beta-D-glucopyranosyl)oxy)propane, and a simple non-cyanogenic glycoside, ethyl beta-D-glucopyranoside, were isolated from an ethanolic extract of the fresh root cortex of Manihot esculenta. From a methanolic extract of the fresh leaves of this species lotaustralin and linamarin, and two flavonoid glycosides, kaempferol-3-O-rutinoside and quercetin-3-O-rutinoside were isolated.