Studies on the constituents of asclepiadaceae plants. LXVI The structures of three new glycosides, cynapanosides A, B, and C, from the Chinese drug "Xu-Chang-Qing," Cynanchum paniculatum Kitagawa.

Three new glycosides named cynapanosides A (1), B (2), and C (3) which contain a new aglycone, glaucogenin D (10), were isolated from Cynanchum paniculatum, in addition to the known compounds, cynatratoside B (5) and 3β, 14-dihydroxy-14β-pregn-5-en-20-one (13). Their structures were elucidated by spectroscopic and chemical methods. The results led us to propose a structure revision of glaucogenin B (11).