A New C21-steroidal Cynansteroid O from Roots of Cynanchum auriculatum.

A new C₂₁-steroidal cynansteroid O (1), together with one new natural product 20-hydroxylateqingyangshengenin (2), and three known compounds (3–5) were isolated from the roots of Cynanchum auriculatum. The chemical structures were elucidated by analyses of physio-chemical properties and spectral data and compared with the published data with given references. Compounds 1–3 were isolated for the first time from the roots of C. auriculatum. [ABSTRACT FROM AUTHOR]