Preparative isolation of monomer catechins and oligomer procyanidin fractions from grape seed extracts by high-speed counter-current chromatography

In this paper, monomer (+)-catechin; (-)-epicatechin and (-)-epicatechin-3-o-gallate, three oligomeric procyanidin fractions (OPCs) and one polymeric procyanidin fractions (PPCs) were successfully separated and isolated from grape seed extracts using semi-preparative TBE-300B high-speed counter-current chromatography (HSCCC). For their separation in monomer (+)-catechin; (-)-epicatechin and (-)-epicatechin 3O-gallate, hexane/ethyl acetate/water (1:10: 10, v/v/v) was selected as solvent system. For separation of OPCs and PPCs, solvent system ethyl acetate/water (1:1, v/v) was selected. Compositional data and mean polymerization degrees of OPCs were determined by phloroglucinolysis method. The purity of each fraction obtained; monomer (+)-catechin (C), (-)-epicatechin (EC) and (-)-epicatechin-3-o-gallate (ECG), verified by UPLC, was 98%, 82% and 71%, respectively. The mean polymerization degrees of the three OPCs fractions were respectively 2.842, 3.521, 4.475. As compared with traditional separation methods for catechins and OPCs, HSCCC has shown to be a powerful and efficient technique for large-scale isolation of these compounds.