C21 steroidal glycosides from the roots of Cynanchum paniculatum.

As a part of our continuing research for bioactive constituents from Cynanchum plants, four new C21 steroidal glycosides, cynapanoside D-G (1-4), together with six known compounds (5-10) were isolated from the roots of Cynanchum paniculatum (Bge.) Kitag. Their structures were elucidated on the basis of 1D- and 2D-NMR spectroscopic data as well as HR-ESI-MS analysis. Compound 8 exhibited potent inhibitory activities against HL-60, HT-29, PC-3 and MCF-7 cell lines with IC50 values of 8.3, 7.5, 34.3 and 19.4μM, respectively and compounds 1-4 and 9 displayed moderate cytotoxicity against the four cell lines. The in vitro antioxidant activities of compounds 1-4, 8 and 9 were assayed by DPPH radical scavenging activity. Antibacterial and antifungal activities of compounds 1-4, 8 and 9 were also tested.