A New C 21 -steroidal Cynansteroid O from Roots of Cynanchum auriculatum

new C 21 -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 .