The relationship between antiglycation activity and procyanidin and phenolic content in commercial grape seed products.

Eight commercial grape seed products (GSPs) were assessed for their inhibition of the formation of advanced glycation end-products in vitro. All 8 commercial GSPs included in this study were potent inhibitors of advanced glycation end-product formation with IC(50) values ranging from 2.93 to 20.0 µg/mL. Total procyanidin content ranged from 60% to 73%. HPLC-DAD-ELSD results indicate that (+)-catechin, (-)-epicatechin, procyanidin B1, and procyanidin B2 were predominant and ubiquitously present in all the products under study, while gallic acid and procyanidin B4 were present in relatively minor amounts. The IC(50) values correlated with total phenolic content, and multiple regression analysis indicated that IC(50) is a linear function of the concentration of gallic acid and procyanidins B1, B2, and B4. Based on this study, GSPs have the potential to complement conventional diabetes medication toward disease management and prevention.