Effect of inorganic salt on partition of high-polarity parishins in two-phase solvent systems and separation by high-speed counter-current chromatography from Gastrodia elata Blume.

Parishins are high-polarity and major bioactive constituents in Gastrodia elata Blume. In this study, the effect of several inorganic salts on the partition of parishins in two-phase solvent systems was investigated. Adding ammonium sulfate, which has a higher solubility in water, was found to significantly promote the partition of parishins in the upper organic polar solvents. Based on the results, a two-phase solvent system composed of butyl alcohol/acetonitrile/near-saturated ammonium sulfate solution/water (1.5:0.5:1.2:1, v/v/v/v) was used for the purification of parishins by high-speed counter-current chromatography. Fractions obtained from high-speed counter-current chromatography were subjected to semi-preparative high-performance liquid chromatography to remove salt and impurities. As a result, parishin E (6.0 mg), parishin B (7.8 mg), parishin C (3.2 mg), gastrodin (15.3 mg), and parishin A (7.3 mg) were isolated from water extract of Gastrodia elata Blume (400 mg). These results demonstrated that adding inorganic salt that has high solubility in water to the two-phase solvent system in high-speed counter-current chromatography was a suitable approach for the purification of high-polarity compounds.