Steroidal saponins from Myriopteron extensum and their cytotoxic activity.

Two new steroidal saponins, extensumsides A ( 1) and B ( 2), were isolated from the whole plants of Myriopteron extensum (Wight) K. Schum. Their structures were elucidated as 17 beta-uzarigenin-3- O- beta-glucopyranosyl-(1-->6)- beta-glucopyranosyl-(1-->4)- beta-thevetopyranosyl-(1-->4)- beta-cymaropyranoside ( 1) and 12-(3-methylbut-2-enoyloxy)pregn-5-en-20-one 3- O-[beta-cymaropyranosyl-(1-->4)-beta-cymaropyranosyl-(1-->4)-beta-thevetopyranosyl-(1-->4)-(6- O-sulfo-beta-glucopyranoside)] ( 2) on the basis of chemical and spectral evidence. Extensumside A exhibited significant cytotoxicity against eight cancer cell lines with a mean GI (50) value of 0.346 microg/mL.