Separation of five oligostilbenes from Vitis amurensis by flow-rate gradient high-performance counter-current chromatography

A rapid and efficient high-performance counter-current chromatography (HPCCC) method was developed to separate five oligostilbenes from the roots of Vitis amurensis. An n-hexane/ethyl acetate/methanol/water system (4:8:4:10, v/v/v/v) was selected as an optimal two-phase solvent system of which the upper phase was used as the stationary phase and the lower phase was used as the mobile one. Partition coefficient values for the target compounds under these optimized conditions were 0.28 (1, ampleosin A), 7.12 (2, (+)-g-viniferin), 2.26 (3, vitisin A), 5.38 (4, wilsonol C), and 11.23 (5, vitisin B). Flow-rate gradient HPCCC (4mL/min in 0-70 min, 8mL/min in 70-250 min) was applied to isolate the target compounds in as high purity as possible within the shortest possible run time. Under these conditions, ampelopsin A (12.1 mg), (+)-g-viniferin (10.4 mg), vitisin A (2.8 mg), wilsonol C (3.2 mg), and vitisin B (37 mg) were isolated with >95% purity from 150 mg of enriched oligostilbene extract. Although the K-D of the last eluted compound, vitisin B (K-D = 11.23), was relatively large, it was eluted in 115-145 min using the two-phase solvent system. This study shows that HPCCC is an efficient tool for the isolation and purification of natural products.