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 (5.6 mg), quercetin‐3′‐O‐D‐glucoside (7.2 mg), quercetin‐3‐O‐β‐D‐glucoside (16 mg), quercetin‐7‐O‐β‐D‐glucoside (8.3 mg), from 100 mg of the crude extract in a one step separation. The structure identification was made by 1H NMR, 13C NMR.