2.3. Fractionation of grape seed extract using high-performance countercurrent chromatography (HPCCC) The grape seed extract (8 g) was added to 160 mL of ethanol and kept under constant stirring. Hexane (450 mL) was slowly dripped into the solution for the sequential precipitation of polymeric material. The suspension was stirred for another 30 min and then filtered. The polar phase containing monomeric and oligomeric flavan-3-ols was freezedried. The remaining solids were dissolved in water and freeze-dried to obtain the higher oligomeric and polymeric procyanidins.