Antagonistic effect of myricetin on platelet activing factor

AimTo study the antagonistic effect of myricetin on platelet activing factor (PAF). MethodsThe specific binding of ［³H］ PAF to rabbit platelet receptor was investigated using radio ligand binding assay (RLBA). Platelet adhesion induced by PAF was measured with spectrophotometry. The elevation of inner free calcium concentration in rabbit polymorphonuclear leukocytes (PMNs) induced by PAF was assayed by Fura-2 fluorescent technique. ResultsThe specific binding inhibition potency of Myr was found to be concentration-dependent. The IC₅₀ of Myr in ［³H］　PAF 1, 2 and 4 nmol·L^-1 were 34.8, 85.7 and 118.6 μmol·L^-1, respectively. The PAF induced reactions of rabbit platelet adhesion and PMNs inner free calcium concentration increase were inhibited by Myr in a dose-dependent manner. The IC₅₀ of Myr to inhibit platelet adhesion was 13.1 μmol·L^-1. ConclusionThe specific receptor binding of PAF can be antagonized by myricetin.