Phytochemical Studies on Astragalus Root (2)- Flavonoids and a Lignan

From the 70% EtOH extract of the roots of Astragalus membranaceus (Leguminosae), eleven flavonoid derivatives and a lignan, were isolated and identified as liquiritigenin (1), daidzein (2), formononetin (3), sophorophenolone (4), calycosin (5), methylnissolin (6), isomucronulatol (7), isomucronulatol 7-O-glucoside (8), methylnissolin 3-O-glucoside (9), calycosin 7-O-glucoside (10), (+)-syringaresinol O--D-glucoside (11), and isomucronulatol 7,2'-di-O-glucoside (12), by spectroscopic methods. This is the second report of the isoflavonoid derivatives sophorophenolone (4) and isomucronulatol 7,2'-di-O-glucoside (12) from a natural source, as well as the first report of compounds liquiritigenin (1), daidzein (2) and (+)-syringaresinol O--D-glucoside (11) from the species A. membranaceus.