Isolation and purification of salvianolic acid A and salvianolic acid B from Salvia miltiorrhiza by high-speed counter-current chromatography and comparison of their antioxidant activity.

Water-soluble salvianolic acid A (Sal A) and salvianolic acid B (Sal B) were successfully isolated and purified from the crude extract of Salvia miltiorrhiza by high-speed counter-current chromatography (HSCCC). The solvent system was n-hexane-ethyl acetate-methanol-water (3:6:6:10, v/v/v/v). 4.27 mg of Sal A and 32.09 mg of Sal B were obtained from 260 mg of the crude sample. The purities of Sal A and Sal B were 96.67% and 97.43%, respectively. Their structures were identified by (1)H NMR and (13)C NMR. Antioxidant activities of Sal A and Sal B were also evaluated and compared by the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+)) radical cation decolourisation assay. Both Sal A and Sal B showed high radical scavenging activities with their EC(50) values being 1.43+/-0.09 and 1.81+/-0.01 microg/ml in DPPH radical method. The ABTS results showed that Sal A and Sal B exhibited high total antioxidant activities, their EC(50) values were 1.35+/-0.00 and 1.43+/-0.01 microg/ml, respectively.