Effect of 3,4-dihydroxyacetophenone on membrane fluidity of platelet by fluorescence polarization analysis

3,4-dihydroxyacetophenone (DHAP) is one of the constituents of Ilex pubesens Hook. Et Arn.var. glaber Chang. It has been found that DHAP inhibited the platelet aggregation in vitro. In the present paper we studied the relationship between the effects of DHAP on platelet aggregation and the change of membrane fluidity by measuring fluorescence polarization of platelet membrane labeled with 1,6-diphenyl-1,3,5-hexatriene (DPH). The degree of fluorescence polarization was increased by the treatment of DHAP at the doses which inhibited platelet aggregation. These results indicate that DHAP decreases the membrane fluidity of platelets, which is related to the inhibition of platelet aggregation.