Antiplatelet activity of soy sauce as functional seasoning

In seeking the functionality of foodstuffs applicable to medicine, soy sauce was found to show antiplatelet activity. Therefore, the active components in soy sauce were purified, structurally identified, and studied for their inhibitory effects on the aggregation of human platelets. Aqueous 2-fold diluents of soy sauce inhibited platelet aggregation induced by collagen and epinephrine depending on the dilution factor. Since a basic extract with diethyl ether completely inhibited collagen-induced aggregation, it was subjected to serial extractions and multistep HPLC fractionations for purifying antiplatelet components. The finally obtained isolates were identified as 1-methyl-1,2,3,4-tetrahydro-beta-carboline and 1-methyl-beta-carboline on the basis of EI-MS, (1)H NMR, diode array, and fluorescence spectra. Their spectral data and chromatographic behaviors were the same as those of synthetic ones. 1-Methyl-1,2,3, 4-tetrahydro-beta-carboline showed mean concentrations (n = 5-6) of 4.6, 4.2, 28.6, 11.6, and 65.8 microgram/mL to produce 50% inhibition of the maximal aggregation response induced by epinephrine, platelet-activating factor, collagen, adenosine 5'-diphosphate, and thrombin, respectively. Its inhibitory effect was much greater than that of 1-methyl-beta-carboline on platelet aggregation by all the tested inducers. The quantitative HPLC analysis revealed that the significant amounts of both antiplatelet compounds were uniformly contained in commercially available soy sauce. From these results, soy sauce may be referred to as functional seasoning containing alkaloidal components with the potent preventive effect on thrombus formation.