Preparative isolation and purification of rupestonic acid from the Chinese medicinal plant Artemisia rupestris L. by high-speed counter-current chromatography.

Rupestonic acid was purified for the first time by high-speed counter-current chromatography from a dichloromethane extract of the traditional Chinese medicinal plant Artemisia rupestris L. The separation was performed in two steps with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (6:4:3.5:6.5, v/v) with 0.5% acetic acid in stationary-phase. From 200 mg of the crude extract, 27.9 mg of rupestonic acid was obtained at over 98% purity as determined by HPLC analysis, and its chemical structure was confirmed by MS, 1H and 13C nuclear magnetic resonance.