Isolation of high-purity casticin from Artemisia annua L. by high-speed counter-current chromatography

Following an initial clean-up step on silica, high-speed counter-current chromatography (HSCCC) was used to purify a flavone, casticin (5,3′-dihydroxy-3,6,7, 4′-tetramethoxyflavone), from an extract of the dried leaves of Artemisia annua L. The two-phase solvent system used was composed of n-hexane–ethyl acetate–methanol–water at an optimized volume ratio of 7:10:7:10 (v/v). HSCCC separation of 226.4 mg of crude sample (containing casticin at 16.5% purity after silica gel clean-up) yielded 36.3 mg of casticin with a purity of over 99% and 96.2% recovery. Identification of the target compound was performed by 1H NMR, 13C NMR, two-dimensional NMR, electrospray ionization MS, IR and UV.