Effects of catechins on human blood platelet aggregation and lipid peroxidation.

The activity of catechins was studied for inhibitory activity in human blood platelets. Platelet aggregation and peroxidation were evaluated in platelet rich plasma (PRP) obtained from samples of healthy volunteers. Human blood platelets were submitted to stimulation with 300 microM arachidonic acid, 3 microM adenosine diphospate (ADP) and 6 microM epinephrine. Treatment with (200 microg/mL) catechin or epicatechin was sufficient to exhibit a potent inhibitory effect of the three agents. The inhibitory effect was dose dependent at concentrations of 20-200 microg/mL. Using malondialdehyde (MDA) as an index of total lipid peroxidation capacity, decreased production of MDA of the platelets treated with catechin or epicatechin after stimulation by arachidonic acid was observed. These findings suggest that catechins protect platelets from peroxidative stress and their aggregation. Copyright 1999 John Wiley & Sons, Ltd.