Bioactive taxoids from the Japanese yew Taxus cuspidata.

A series of new taxoids, named taxuspines A-H and J-Z (1-25) and taxezopidines A-H and J-L (26-36), have been isolated together with 37 known taxoids (37-73) including paclitaxel (53) from the Japanese yew, Taxus cuspidata Sieb. et Zucc. (Taxaceae). These new taxoids possess various skeletons containing 5/7/6, 6/10/6, 6/5/5/6, 6/8/6, or 6/12-membered ring systems. Among the new taxoids, some non-taxol-type compounds remarkably reduced CaCl(2)-induced depolymerization of microtubules, or increased cellular accumulation of vincristine in multidrug-resistant tumor cells as potent as verapamil. On the other hand, chemical derivatization of taxinine (37), one of major taxoids obtained from this yew, led to the discovery of unusual reactions of taxinine derivatives. Here we describe our recent results on the isolation, structure elucidation, and bioactivity of these new and known taxoids and the formation of unexpected products of the unusual reactions of taxinine.