C21 Steroidal Saponins from Cynanchum otophyllum

ObjectiveTo study the chemical structures of saponins in the rhizome of Cynanchum otophyllum (Asclepiadaceae), and to find new compounds.MethodsThe total saponins of the rhizome were separated by silica gel column chromatography. The chemical structures of obtained compounds were determined by NMR and FAB-MS spectra.ResultsThree C21 steroidal saponins were separated. Their structures were determined as caudatin 3-O-β-D-glucopyranosyl-(1→4)-β-D-digitoxopyranosyl-(1→40)-β-D-digino-pyranosyl-(1→4)-α-D-oleandropyranoside (1), caudatin 3-O-β-D-oleandropyranosyl-(1→4)-α-D-oleandropyranosyl-(1→4)-α-D-oleandropyranoside (2), and caudatin 3-O-β-D-glucopyranosyl-(1→4)-α-D-oleandropyranosyl-(1→4)-β-D-diginopyranosyl-(1→4)-α-D-oleandropyranoside (3), respectively.ConclusionSaponins 1–3 are new compounds.