Preparative isolation and purification of acetophenones from the Chinese medicinal plant Cynanchum bungei Decne. by high-speed counter-current chromatography

Four acetophenones, baishouwubenzophenone (1), 4-hydroxyacetophenone (2), 2,4-dihydroxyacetophenone (3) and 2,5-dihydroxyacetophenone (4), were successfully isolated and purified from the Chinese medicinal plant Cynanchum bungei Decne. by high-speed counter-current chromatography (HSCCC) using a pair of two solvent system, one consisting of light petroleum–ethyl acetate–methanol–water (2:5:3:3, v/v) and another of light petroleum–ethyl acetate–methanol–water (2:4:3:3, v/v). A total of 62.3 mg (1), 18.9 mg (2), 15.0 mg (3) and 4.5 mg (4) were purified from the n-butanol extract (600 mg) of crude sample of C. bungei Decne. in one-step separation within 5 h, each at over 96% purity as determined by high performance liquid chromatography (HPLC). Their structures were identified by Mass Spectrometer (MS), Nuclear magnetic resonance (1H NMR and 13C NMR).