Separation of Four Compounds from Forsythia suspensa by Counter-Current Chromatography with Stepwise Elution

High speed counter-current chromatography technique in preparative scale has been successfully applied to separate and purify main compounds from the ethyl acetate extract of Forsythia suspense using stepwise elution with two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (1:4:1:4, v/v) and (1:4:2:3, v/v). Under the optimized conditions, the preparative high-speed counter-current chromatography was performed on 350 mg of the ethyl acetate yielding phillyrin (12.8 mg), isolariciresinol-9'-O-beta-D-glucopyranoside (5.3 mg), pinoresinol (21.2 mg), and phillygenin (8.3 mg) in a one-step separation, with purities over 90% as determined by HPLC. The structures of the separated compounds were identified by HPLC-MS and (HNMR)-H-1.