Soy isoflavones as potential inhibitors of Alzheimer ß-amyloid fibril aggregation in vitro

Abstract

The effect of soy isoflavones on cognitive function and their beneficial effects on certain neurogenerative diseases have been at the center of a growing debate. The aggregation of amyloid ß-peptide and its accumulation in the brain has been identified as one of the major steps in the physiopathology of Alzheimer's disease. Since some polyphenols are already known to have anti-amyloidogenic activities, the present study was designed to examine the hypothesis that soy isoflavones (daidzein, daidzin, genistein, genistin and equol) may inhibit amyloid ß-peptide fibril formation in vitro. Among the isoflavones tested, only the aglycones and equol (the major metabolite of daidzein) showed an inhibition higher than 30% of fibril formation. These results raise the hypothesis that soybean isoflavones may have a nutritional value in preventing the physiopathology of Alzheimer disease, and therefore support further analysis of the neurocognitive benefits of soy consumption.