Effects of aqueous extracts of onion, garlic and ginger on platelet aggregation and metabolism of arachidonic acid in the blood vascular system: in vitro study.

Aqueous extracts of onion, garlic and ginger were found to inhibit aggregation induced by ADP, epinephrine, collagen and arachidonate in a dose-dependent manner in vitro. In the case of onion and garlic extracts relatively much higher volumes were need to bring about even a modest inhibition (by ca. 13-18%) of thromboxane synthesis in washed platelets from labelled AA. On the other hand a good correlation was found between the amounts of ginger extract needed to inhibit platelet aggregation and those to inhibit platelet thromboxane synthesis. Ginger extract reduced also platelet prostaglandin-endoperoxides. A dose-related inhibition of platelet thromboxane- and prostaglandin (PGF2 alpha, PGE2 and PGD2) synthesis was affected by ginger extract. Extracts of onion, garlic and ginger inhibited biosynthesis of prostacyclin in rat aorta from labelled AA. Ginger extract mildly inhibited the synthesis of prostacyclin from endogenous pool of AA in rat aorta; the other two extracts were without effect.