Structure determination of two new C21 steroidal glycosides from Cynanchum komarovii.

Two new 13,14:14,15-disecopregnane-type C21 steroidal glycosides, namely komarosides R (1) and S (2), along with four known compounds (3-6), were obtained from the 95% ethanol extract of the whole herbs of Cynanchum komarovii Al.Iljinski (Asclepiadaceae). The structures of new compounds were elucidated on the basis of 1D, 2D NMR spectroscopic data and acid hydrolysis. Compounds 1 and 2 showed potent inhibitory activities against human leukemia cell line (HL-60) with IC50 values being 6.2 and 17.6 µM, respectively, compared to the positive control 5-fluorouracil (6.4 µM).