Preparative isolation and purification of four flavonoids from Flos Gossypii by high-speed countercurrent chromatography

Following an initial cleanup step on the AB-8 macroporous resin, high-speed countercurrent chromatography (HSCCC) was successfully applied for the first time to the isolation and purification of four flavonoids from Flos Gossypii. HSCCC was performed with a two-phase solvent system composed of chloroform-methanol-isopropanol-water (5:5:1:3, v/v) adding 0.4% phosphoric acid in the aqueous stationary phase. The separation yielded quercetin (5.6mg), quercetin-3'-O-D-glucoside (7.2mg), quercetin-3-O-beta-D-glucoside (16mg), quercetin-7-O-beta-D-glucoside (8.3mg), from 100mg of the crude extract in a one step separation. The structure identification was made by (1)H NMR, (13)C NMR.