RESUMO
Objective: To study the chemical structures of saponins in the rhizome of Cynanchum otophyllum (Asclepiadaceae), and to find new compounds. Methods: The 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. Results: Three 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. Conclusion: Saponins 1-3 are new compounds.