Pterocarpans and Isoflavans from Astragalus membranaceus (Fisch.) Bunge

A new pterocarpan, (6aR, llaR)-3, 9-dimethoxy-l0-hydroxypterocarpan with four known compounds, (6aR,11aR)-3,9,10-tri-methoxypterocarpan,9,l0-di-methoxypterocarpan-3-O-β-D-glucopyranoside, (3R)-2'-hydroxy-7, 3', 4'-trimethoxy-isoflavan, 2'-hydroxy-3', 4'- dimethoxyisoflavan-7-O-β-D-glucopyranoside, were isolated from ethanolic extract of the root of Astragalus membranaceus (Fisch.) Bunge. Their structures were elucidated by means of spectral analysis and chemical conversions.