Steroidal saponins from Dioscorea preussii

Three new steroidal saponins, named diospreussinosides A-C (1-3), along with two known ones (4, 5) were isolated from rhizomes of Dioscorea preussii. The spirostane-type skeleton of compound 3 with an unusual dihydroxylation pattern on the F-ring is reported for the first time. Cytotoxicity of 2-5 was evaluated against two human colon carcinoma cell lines (HT-29 and HCT 116). The most active compound was a derivative of pennogenin (5).92