Oligomeric and polymeric procyanidins from grape seeds

Five tannin fractions were isolated from grape (Vitis vinifera) seeds. HPLC analysis of the degradation products released by thioacidolysis showed that all fractions consisted of catechin, epicatechin and epicatechin gallate units. Epicatechin was the major component in the extended chain. Catechin was more abundant in terminal units than in extension units. The proportion of galloyllated units varied from 13% to 29% as the Mr, increased. Mean degrees of polymerization ranging from 2.3 to 15.1 (by thiolysis) and from 2.4 to 16.7 (by GPC) were determined.