α-Glucosidase Inhibitory and Cytotoxic Taxane Diterpenoids from the Stem Bark of Taxus wallichiana.

From a CHCl extract of the bark of Taxus wallichiana, six new taxoids, wallitaxanes A-F (1-6), were isolated, together with 29 known compounds. The structures of the new compounds were elucidated on the basis of spectroscopic data interpretation. Wallitaxane D (4) was identified as an opened oxetane-type taxoid having the first naturally occurring C(H)-20 acetal group, while wallitaxanes E (5) and F (6) are representative of the rare abeo-taxoid class.