Potentiation of antiaggregating effect of prostaglandins by alpha-tocopherol and quercetin

Prostaglandin (PG) I2 (prostacyclin), PGE1 and their analogues are effective inhibitors of platelet aggregation. However, a clinical use of these compounds for the treatment of cardiovascular diseases is restricted due to unwanted side effects. Alpha-tocopherol and quercetin are weak antiplatelet agents. At the same time, they have mild if any side effects when consumed medicinally. The aim of this work was to study the possibility to decrease the effective antiplatelet concentrations of PGs combining them with alpha-tocopherol or quercetin. Platelet-rich plasma (PRP) was prepared from human blood. The inhibition of adenosine diphosphate-induced platelet aggregation was caused by PGs in the presence and absence of alpha-tocopherol or quercetin and corresponding concentration-effect curves were obtained. At a subthreshold concentration 200 and 2 microM, respectively, both alpha-tocopherol and quercetin essentially increased the antiplatelet effects of PGI2, PGE1 and iloprost. Especially effective was the combination of alpha-tocopherol with low concentrations of iloprost. Thus, combination of PGs with alpha-tocopherol or quercetin allows the use of prostaglandins at lower concentrations to inhibit platelet aggregation.