Abstract: Kadsurenone (Kad) is a lignan isolated from the Chinese herbal plant Heifenteng (Piper futokadsura). In the present paper the effects of Kad on PAF receptor using radioligand binding assay, as well as on rabbit platelet aggregation are reported. The experimental results indicated that Ked is a potent and specific PAF antagonist. The Ki value of Kad binding PAF receptor of washed rabbit platelets was found to be 2×10^-12 mol/L. Experiment in vitro showed that the rabbit platelet aggregation induced by PM was inhibited by Kad (IC50 = 2.6 μmol/L). However, no inhibitory effecton the aggregation induced by arachidonic acid and ADP was observed. Kad (0.1 mg/kg, iv)completely inhibited PAF-induced platelet aggregation in rabbits and the effect lasted for 2 hr. The formation of platelet thrombus in rats was inhibited by iv Kad (7.1 mg/kg; 14.2 mg/kg) or po (80 mg/kg, 120 mg/kg).The inhibitory rate of Kad was 25.4%, 38.2%, 21.4% and 34.6% respectively. It issuggested that the PAF is an important factor in thrombosis and Kad is a specific PAF receptor an-tagonist .

Key words: Platelet Activating Factor (PAF), Kadsurenone (Kd), Receptor, Platelet, Thrombosis