Comparative study of the anti-platelet effects of cis- and trans-resveratrol

Although various biological activities of resveratrol have been extensively studied, most reports have focused on trans-resveratrol and little attention has been paid to the cis-isomer. In this study, the effect of cis-resveratrol on platelet activity was examined and compared with that of the trans-isomer. Treatment with cis-resveratrol resulted in inhibition of platelet aggregation induced by thrombin, collagen or ADP, which are representative aggregation-inducing agents, and the trans-isomer elicited the same effects. These effects were concentration-dependent in the range of 1-100 μM. However, the potency of the cis-isomer was much lower than that of the trans-isomer; the IC₅₀ values for the cis-isomer versus the trans-isomer were 31 ± 12 vs 15 ± 3, 16 ± 3 vs 9 ± 4, and 60 ± 15 vs 25 ± 6 μM for thrombin-, collagen- and ADP-induced aggregation, respectively. These results indicate that cisresveratrol has a less potent anti-platelet activity, compared with the trans-isomer, and raise the possibility that the biological activities of the cis-isomer may be different from those of the trans-isomer. It will be necessary to evaluate the activity of cis-resveratrol independently of the trans-isomer.