Isoflavonoids are metabolized by human microflora into small phenolic compounds including equol, O-desmethylangolensin, 2-(4-hydroxyphenyl) propionic acid (HPPA) and 4-ethylphenol. In this study we analyzed their effects on platelet aggregation in human blood encompassing the analysis of the mechanism of action; and their interaction with transition metals iron and copper at different pathophysiologically relevant pH conditions.