[Studies on constituents of the Chinese traditional drug baishouwu (Cynanchum auriculatum Royle ex Wight)].

The botanical source of Baishouwu are chiefly the root tuber of Cynanchum auriculatum Royle ex Wight, family Asclepiadaceae. In this paper, the separation and the structure elucidation of three pregnane ester type aglycones and a benzophenone derivative from this plant are described. On the basis of UV, IR, ~1HNMR, ~(13)CNMR and MS spectroscopic analysis the compounds were identified as caudatin Ⅰ, kidjolanin Ⅱ, metaplexigenin Ⅲ and baishouwubenzophenone Ⅳ, the last one being a new natural product.