Effect of Oriental Plant Drugs on Platelet Aggregation; III1. Effect of Chines Drug “Xiebai” on Human Platelet Aggregation

The effect of the Chinese crude drug “Xiebai” and its components on human platelet aggregation induced by 2 µM ADP was studied. From the ethyl acetate-soluble fraction giving a remarkable inhibitory effect against platelet aggregation, N-p -coumaroyltyramine ( 1 ) and N-trans -feruloyl tyramine ( 2 ) were isolated as the active principles. Compound 2 showed a strong inhibitory activity against both the primary and secondary wave aggregation induced by 2 µM ADP of human platelet, whereas 1 was effective only against the primary aggregation. In comparison with the above compounds cinnamic acid derivatives ( 3 - 6 ) and tyramine ( 7 ) were also examined with respect to human platelet aggregation. Compounds 3 and 5 showed the inhibitory activity against both the primary and secondary wave aggregation as did as 2 , while 6 inhibited only the primary aggregation, and 4 gave a lower effect. Compound 7 showed inhibition only upon the secondary aggregation.