title: Inhibition in vitro of platelet aggregation and arachidonic acid metabolism by flavone.
abstract: The effects of flavone on platelet aggregation and arachidonic acid (AA) metabolism were tested in vitro. When incubated at a concentration of 50 microM, flavone completely suppressed platelet aggregation induced by 150 microM AA in thirty-six out of forty-three subjects tested. A lower concentration (10 microM) was effective in about 50% of the donors. Flavone also inhibited the second wave of aggregation induced by epinephrine and ADP. Platelet thromboxane formation, estimated both by radioimmunoassay measurements and by studies of 14C-labeled AA metabolism, was depressed by flavone. Flavone-treated platelets preferentially utilized [14C]AA for the lipoxygenase pathway while cyclo-oxygenase activity was depressed. Adenosine 3':5'-cyclic monophosphate (cAMP) was measured in flavone-treated and control platelets. While their baseline levels were similar, flavone-treated platelets showed a lower stimulation of cAMP induced by prostacyclin (PGI2) than did controls. Phosphodiesterase activity was not affected by flavone as judged from the decay rates of PGI2-stimulated cAMP levels. From these findings we conclude that the antiaggregating activity of flavone is not a consequence of changes in platelet cAMP but is due to inhibition of cyclo-oxygenase.
mesh_terms: D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism; D000242:Cyclic AMP / Q000097:blood; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D010084:Oxidation-Reduction; D010974:Platelet Aggregation / Q000187:drug effects*
chemical_list: D001095:Arachidonic Acids; D005419:Flavonoids; D016718:Arachidonic Acid; D000242:Cyclic AMP