N-3 FATTY ACID-INDUCED LIPID-PEROXIDATION IN HUMAN PLATELETS IS PREVENTED BY CATECHINS

The effects of catechins were studied in both unstimulated platelets a nd platelets submitted to a mild oxidative stress induced by docosahex aenoic acid (DHA). Human unstimulated platelets were incubated in the presence of catechin or epicatechin (1, 10 or 100 mu M) for 2 h at 37 degrees C. Treatment by 1 mu M epicatechin was sufficient to induce a significant inhibition (-30%) of basal thromboxane B-2 formation. This result is consistent with the observed inhibitory effects of flavonoi ds on platelet aggregation. DHA treatment of platelets decreased the a mount of alpha-tocopherol and increased the malondialdehyde (MDA) form ation. The presence of epicatechin or catechin prevented the oxidative stress induced by DHA. Indeed, the platelet alpha-tocopherol level wa s significantly increased when compared to that of platelets treated b y DHA alone, to reach the control level, whereas MDA was depressed to a level even lower than the control one. Our results indicate that cat echin and especially epicatechin protect platelets from a peroxidative stress.