SSGE and DEE, new peptides isolated from a soy protein hydrolysate that inhibit platelet aggregation

A soy protein hydrolysate was found to inhibit rat platelet aggregation induced by ADP, an aggregating agent. To find out its principal antiplatelet peptide(s), the soy protein hydrolysate was separated successively by gel filtration chromatography, reverse-phase HPLC, and cation exchange HPLC. During the course of separation, we observed that most fractions had antiplatelet effects, which suggests that most peptides have some degree of antiplatelet effect. Following the inhibitory fractions, we purified and identified two new peptides, SSGE and DEE, by LC–electrospray ionization MS and peptide sequencing. Both peptides were highly hydrophilic. The concentrations to obtain 50% inhibition (IC50) of the aggregation intensity were approximately 480 and 460 μM, respectively, for SSGE and DEE.