The flavanol (-)-epicatechin and its metabolites protect against oxidative stress in primary endothelial cells via a direct antioxidant effect.

Accumulating evidence suggests that foods rich in flavanols decrease the developing cardiovascular diseases. Attenuation of oxidative stress was to contribute to the cardiovascular benefit of flavanols. Up to now it unclear whether flavanol metabolites can also protect cells from stress. The aim of the present study was to determine the potential of several glucuronidated, methylated and sulfated metabolites of (-)- (EC) and (+)-catechin (Cat) to the protection of human vascular (HUVECs) against oxidative stress. The relative potency of the tested to scavenge superoxide anion radicals showed that a free catechol moiety molecule is important for the direct antioxidant activity. EC and Cat 10microM) were potent radical scavengers and provided protection against intracellular oxidative stress induced by hydrogen peroxide. Although metabolites provided less intracellular protection compared to EC and tested methylated and glucuronidated metabolites reduced oxidative significantly in HUVECs. Our results indicate that the metabolites have relevant contribution in the intracellular protection of EC and Cat oxidative stress. Also, the direct antioxidant activity plays an in this protection.