IN-VITRO EFFECT OF AVARONE AND AVAROL, A QUINONE HYDROQUINONE COUPLE OF MARINE ORIGIN, ON PLATELET-AGGREGATION/

We investigated the effect on human platelet aggregation of the natura lly occurring quinone/hydroquinone couple, avarone and avarol. Avarone exerted antiplatelet activity both on platelet-rich plasma and, to a greater extent, on washed platelets. The quinone inhibited the platele t aggregatory process with all the agonists used. The highest inhibito ry potency occurred with arachidonic acid or A23187 as stimulating age nts. In the case of agonists such as adenosine 5' diphosphate. platele t-activating factor or U46619, the antiaggregatory effect was more pro nounced on the second wave. Inhibition of the aggregatory process para lleled thromboxane B2 formation. Avarol also exerted antiplatelet acti vity, even though its inibitory potency was much lower than that of av arone.