EFFECT OF QUERCETIN ON CHEMILUMINESCENCE OF HUMAN PLATELETS INDUCED BY ARACHIDONIC-ACID

Arachidonic acid (AA)-induced platelet chemiluminescence (CL) was meas ured with a lumiphotometer. Quercetin remarkably inhibited the CL, the IC50 of quercetin was 3 mumol . L-1. When quercetin plus aspirin,whic h inhibits only cyclooxygenase, was added,the inhibitory rate of plate let-CL obviously increased (P < 0.01). On the other hand, the querceti n had a scavenging effect on superoxide anion radical using alkaline s odium dithionite solution generation. The IC50 was 20. 9 mumol . L-1. In addition 9 superoxide dismutase of 0.1 mg . ml-1 inhibited the plat elet-CL by 97.8%, while mannitol, a hydroxyl radical scavenger, only b y 43.3% at a concentration of 80 mg . ml-1. These results suggest that the mechanism of the inhibiting AA-induced platelet-CL by quercetin w as associated with scavenging the superoxide anion radical directly an d with inhibiting the cyclooxygenase.