Piperlongumine, a constituent of Piper longum L., inhibits rabbit platelet aggregation as a thromboxane A(2) receptor antagonist.

Piper longum L. has been used as a crude drug for the treatment of the disorder of peripherally poor blood circulation in Asia. In the present study, we examined the effect of piperlongumine, a constituent of P. longum L., on rabbit platelet aggregation. Piperlongumine concentration-dependently inhibited platelet aggregation induced by thromboxane A(2) receptor agonist U46619, but it only slightly inhibited thrombin-induced one. Piperlongumine also inhibited U46619-induced phosphatidylinositol hydrolysis and the binding of [(3)H]SQ29548 to thromboxane A(2) receptor with a similar concentration-dependency to the aggregation. It is assumed that piperlongumine inhibits platelet aggregation as a thromboxane A(2) receptor antagonist.