Study on Relationship Between Degree of Polymerization and Radical Scavenging Capacity of Grape Seed Procyanidins

DPPH·and two chemical irritant light reactions were used for comparing the radical scavenging capacity of grape seed procyanidin fractions with different degree of polymerization(DP). Results showed that the DPPH· scavenging capacity of procyanidins was higher than VC, VE and BHT, with IC50 being 1.8, 2.5, 6.3, 3.5μg/ml respectively. For O·2, the scavenging ability of procyanidins was higher than VE and similar to VC. When compared on base of mass concentration, fractions with different DP has almost the same DPPH· scavenging capacity. But for HO·and O·2, the scavenging ability of procyanidins decreased with increase of DP. When compared on base of mol concentration, procyanidins have an increasing radical scavenging capacity as the DP increase. It seems that the antioxidant activity of procyanidins were dependent on the solvent used in the reaction system. In water, the antioxidant activity of single phenolic hydroxyl in procyanidin molecule decreased as the DP increase.