Abstract: A novel natural platelet-activating factor (PAF) antagonist was isolated from a Chinese medicinal. herb Viscum coloratum and its structure was identified as ho moeriodictyol-7-O-β-D-glycoside, which existed in ethyl acetate extract fraction. At the final concentration of 10^-5 mol·L^-1, it could significantly inhibit human and rabbit platelet aggregation induced by PAF, with IC50 being 8.0×10^-7 mol·L^-1, but had no inhibitory effect on platelet aggregation induced by ADP.

Key words: Viscum coloratum, Platelet-activating factor antagonist, Viscum coloratum, Platelet-activating factor antagonist, Homoeriodictyol-7-O-β-D-glycoside, Homoeriodictyol-7-O-β-D-glycoside, Platelet aggregation, Platelet aggregation