Platelet-activating factor (PAF) recepptor binding activity of the root bopf enicosanthellum pulchrum

Abstract

The hexane, ethyl acetate and methanol extracts of the root ofEnicosanthellum pulchrum (Annonaceae) were investigated for their inhibitory effects on platelet-activating factor (PAF) receptor binding to rabbit platelets using 3 H-PAF as a ligand. Cedro I, a known PAF antagonist from natural products was used as a positive control in the bioassay. Among the three extracts, the ethyl acetate was the most active with 85.6 % inhibition and gave IC50 value of 1.7 ?? 0.3 ug/ml. Further fractionation of this extract using vacuum liquid chromatography yielded six fractions (1- VI). Fraction V displayed the highest inhibitory activity of 71.2 %, followed by fraction VI with 67.9 % inhibition. Fraction I-IV exhibited moderate inhibitory effects between 40 to 60 % inhibition. The results suggest the possibility that the root extract may contain promising PAF receptor binding inhibitor.