New 23-spirocholestane derivatives from Ypsilandra thibetica.

Three new unusual 23-spirocholestane derivatives, ypsilanogenin (1), ypsilanogenin 3-O-β-D-glucopyranoside (2), and 4'-acetylypsilanogenin 3-O-β-D-glucopyranoside (3), were isolated from the whole plants of Ypsilandra thibetica. The structures of compounds 1-3 were deduced by spectroscopic and chemical methods, and the structure of 1 was further confirmed by a single-crystal diffraction analysis. All isolates were evaluated for their inhibitory activities against HIV-1. Georg Thieme Verlag KG Stuttgart · New York.