New taxane diterpenoids from the roots of Taxus mairei.

Two new taxoids, taxumairols A (1) and B (2), have been isolated from extracts of the roots of Formosan Taxus mairei (Lemee & Levl.) S. Y. Hu. The structures of 1 and 2 were identified as 5 alpha, 7 beta, 9 alpha, 10 beta, 13 alpha-pentaacetoxy-20-(benzoyloxy)- 2 alpha, 4 alpha-dihydroxytax-11-ene and 2 alpha, 5 alpha, 10 beta,-13 alpha-tetraacetoxy-1 beta, 7 beta, 9 alpha-trihydroxy-4 beta,20-epoxytax-11-ene, primarily on the basis of 1D- and 2D-NMR techniques including DEPT, COSY, and HMBC experiments, as well as chemical correlation with known compounds. Taxumairol A (1) exhibited significant cytotoxicities against murine P-388 and human KB-16, A-549, and HT-29 tumor cell lines.