Isolation and purification of flavonoid glucosides from Radix Astragali by high-speed counter-current chromatography

High-speed counter-current chromatography methods, combined with resin chromatography were applied to the separation and purification of flavonoid glycosides from the Chinese medicinal herb, Radix Astragali. Five flavonoid glycosides, namely calycosin-7-O-beta-d-glucoside, ononin, (6aR, 11aR)-9,10-dimethoxypterocarpan-3-O-beta-d-glucoside, (3R)-2'-hydroxy-3',4'-dimethoxyisoflavan-7-O-beta-d-glucoside and calycosin-7-O-beta-d-glucoside-6''-O-acetate, were obtained. Among them, calycosin-7-O-beta-d-glucoside-6''-O-acetate was preparatively separated from Radix Astragali for the first time. Their structures were identified by ESI-MS, (1)H NMR, (13)C NMR, and 2D NMR.