Characterization of a potent inhibitor of platelet aggregation and release reaction isolated from allium sativum (garlic).

When added to platelet-rich plasma, aqueous extracts of garlic inhibited platelet aggregation and the release reaction. Subsequent experiments designed to characterize the inhibitory component revealed that the inhibitory activity was i) associated with small molecular-weight components, ii) the inhibitory component possessed the typical garlic odor and contained an abundance of sulfur, iii) the inhibitory activity could be extracted with organic solvents, and iv) temperatures above 56 degrees C and alkaline pH above 8.5 quickly destroyed the inhibitory activity. The Rf value of the major inhibitory component after thin-layer chromatographic separation was similar to that of allicin, an unique thiosulfinate in garlic previously shown to possess strong antibiotic and antifungal properties. Allicin was synthesized. On thin-layer chromatographic plates, allicin co-migrated with the inhibitory component in garlic. At 10 microM concentration, allicin inhibited completely platelet aggregation and the release reaction. Comparative studies suggest that the major platelet aggregation and release inhibitor in garlic may be allicin.