Salicylates and 12-lipoxygenase activity in human washed platelets

In vitro salicylates /aspirin, salicylic acid, salicylamide and gentisic acid/ inhibited formation of 12-lipoxygenase products in intact human washed platelets which were stimulated with thrombin or arachidonic acid. Salicylates did not affect 12-lipoxygenase activity in platelet lysates. Ex vivo aspirin or salicylamide at a dose of 1 g given orally to healthy volunteers potentiated formation of 12-lipoxygenase products in washed platelets. It is concluded that the effect of salicylates on 12-lipoxygenase pathway is independent from their influence on cyclooxygenase activity in platelets and aspirin cannot be considered as a selective inhibitor of platelet cyclooxygenase.