Clovamide-type phenylpropenoic acid amides, N-coumaroyldopamine and N-caffeoyldopamine, inhibit platelet-leukocyte interactions via suppressing P-selectin expression.

N-Coumaroyldopamine and N-caffeoyldopamine are clovamide-type phenylpropenoic acid amides found in Theobroma cacao. In this article, N-coumaroyldopamine and N-caffeoyldopamine were investigated to determine their effects on P-selectin expression and platelet-leukocyte interactions in vitro and in vivo models. At the concentration of 0.05 microM, they were able to inhibit P-selectin expression on the platelets by 33 (P < 0.011) and 30% (P < 0.012), respectively. The inhibition was partially blocked by beta(2)-adrenoceptor antagonists, suggesting that beta(2) receptors are probably engaged in the inhibition. N-Caffeoyldopamine and N-coumaroyldopamine could also suppress platelet-leukocyte interactions in blood samples by 36 (P < 0.013) and 32% (P < 0.011), respectively, at the same concentration (0.05 microM). In an animal study, mice administrated orally with N-caffeoyldopamine (50 and 100 microg/35 g of body weight) also showed great reduction in the P-selectin expression and platelet-leukocyte interactions by 31 to 45% (P < 0.011) and 34 to 43% (P < 0.014), respectively. These data suggest that the clovamide-type phenylpropenoic acid amides are able to suppress platelet-leukocyte interactions via inhibiting P-selectin expression.