In Vitro but not In Vivo Alan Chait.
Soy products contain several isoflavones, the most abundant of which is genistein.
Genistein is a tyrosine kinase inhibitor, inhibits angiogenesis and has a chemical structure that suggests that it might have antioxidant properties. Therefore, the effect of genistein, and another soy isoflavone, daidzein, which also has antioxidant potential, were tested for their ability to inhibit LDL oxidation in vitro and in vivo. Both genistein and daidzein inhibited LDL oxidation in a time and concentration dependent manner in vitro. Genistein was a more effective antioxidant than daidzein. LDL that was subjected to oxidant stress in the presence of these isoflavones was taken up and degraded by macrophages to a lesser extent than was LDL oxidized in their absence.