C-21 steroidal glycosides from the roots of Cynanchum chekiangense and their immunosuppressive activities.

Two new C21 steroidal glycosides, chekiangensosides A and B, were isolated from the roots of Cynanchum chekiangense, together with two known compounds. On the basis of chemical evidence and extensive spectroscopic methods, including one-dimensional and two-dimensional NMR, the structures of two new compounds were identified as cynajapogenin A, 3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-alpha-L-cymaropyranosyl-(1-->4)-beta-D-cymaropyranoside, and glaucogenin A, 3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-alpha-L-cymaropyranosyl-(1-->4)-beta-D-cymaropyranoside, respectively. The two known steroidal glycosides, and were revised. These isolated compounds were tested for their immunological activities in vitro against concanavalin A (Con A)- and lipopolysaccharide (LPS)-induced proliferation of mice splenocytes. Compounds showed immunosuppressive activities in vitro in a dose-dependent manner.