THE ANTAGONIST EFFECTS OF COMPOUNDS DERIVED FROM KHELLACTONE ON PLATELET-ACTIVATING FACTOR

Abstract

Crude coumarin constituents of Peucedanum praeruptorum Duun. including praeruptorin A (=Pd-Ia)(2) and B (=Pd-II)(11) had an antagonistic effect on a specific platelet activating factor (PAF) in the platelet aggregation induced by several aggregating agents. This provides a new class of PAF antagonists. Studies of the structure-activity relationship with khellactone (1) derivatives and PAF antagonistic activity indicate that the cis isomers of 1 at the C-3' and C-4' positions are more favorable than trans isomers, and the acyl moiety at the C-3' position of 1 requires an appropriate molecular size.