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

Two new C21 steroidal glycosides, chekiangensosides A (1) and B (3), 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-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-α-l-cymaropyranosyl-(1 → 4)-β-d-cymaropyranoside, and glaucogenin A, 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-α-l-cymaropyranosyl-(1 → 4)-β-d-cymaropyranoside, respectively. The two known steroidal glycosides, 2 and 4, 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 1–4 showed immunosuppressive activities in vitro in a dose-dependent manner.