C21-steroidal glycosides and sesquiterpenes from the roots of Cynanchum bungei and their inhibitory activities against the proliferation of B and T lymphocytes

Abstract

Phytochemical investigation of the roots of Cynanchum bungei Decne (Asclepiadaceae) led to the elucidation of seven C₂₁-steroidal glycosides (1-7) including three new compounds (1-3), named cynabungosides A-C, one new eudesmane-type sesquiterpene (8), named cynabungone, and one new humulane-type sesquiterpene (9), named cynabungolide. Their structures were elucidated on the basis of extensive spectroscopic analysis. The absolute configurations of 8 and 9 were defined unequivocally by ECD analysis and X-ray crystallography, respectively. A putative biosynthetic pathway of humulane-type sesquiterpenes 9 and 10 is proposed.

Keywords: C(21)-steroidal glycosides; Cynanchum bungei; Sesquiterpenes.