[Study on glycosidal constituents from Epigynum auritum].

A known compound and a new glycoside, epigeoside, were isolated from the rhizomes of Epigynum auritum (Schneid.) Tsiang et P. T. Li (Apocynaceae). The structure of known compound was identified as daucosterol (beta-sitosterol-beta-D-glucopyranoside). The structure of epigeoside has been deduced on the basis of spectral analysis and chemical reactions as catechin-3-O-alpha-L-rhamnopyranosyl-(1----4)-beta-D-glucopyranosyl-(1-- --6) -beta-D-glucopyranoside. Partial hydrolysis of II with 0.2 mol/L HCl afforded compound IIa and rhamnose. Acid hydrolysis of IIa with 2 mol/L HCl afforded an aglycone which was identified by comparison with catechin, and glucose.