Five New C21‐Steroidal Sapogenins from the Acid Hydrolysate of Cynanchum otophyllum Roots

Abstract Five new C 21 ‐steroidal sapogenins ( 1 – 5 ) named cynotogenins J−N, were isolated from the acid hydrolysate of Cynanchum otophyllum roots. Their structures were established by extensive spectroscopic analysis (UV, IR, HR‐ESI‐MS, and NMR). Most notably, compounds 1 – 3 harboring a rare 5β,6β‐epoxy group in the C 21 ‐steroidal skeleton of Cynanchum plants. All compounds were evaluated for their cytotoxicities against multiple cancer cell lines, in which compounds 5 showed weak cytotoxicity against HepG2 cancer cells with IC 50 values of 44.90 μM.