19-Hydroxybaccatin III, 10-Deacetylcephalomannine, and 10-Deacetyltaxol: New Antitumor Taxanes From Taxus wallichiana

Abstract

Activity-guided, chromatographic fractionation of a polar extract of T. wallichiana Zucc. (originally identified as Cephalotaxus mannii Hook.) resulted in the isolation of 3 new KB [human oral epidermoid carcinoma] cytotoxic taxane derivatives. NMR and mass spectral analyses permitted their characterization as 19-hydroxybaccatin III, 10-deacetylcephalomannine and 10-deacetyltaxol. The latter 2 compounds, which are also active against PS leukemia [mouse lymphocytic] in vivo, were observed to be especially labile, each forming equilibrium mixtures with their cytotoxic C-7 epimers.