THE OESTROGENIC ACTIVITY OF RED CLOVER ISOFLAVONES AND SOME OF THEIR DEGRADATION PRODUCTS

SUMMARY The oestrogenic activities of the isoflavones biochanin A, genistein, formononetin and daidzein have been measured at three dose levels using the mouse uterine weight assay. The relative activities found were: genistein 1·5, biochanin A 1·0, daidzein 0·4. Formononetin had very little orno oestrogenic activity. The equivalent activity of a sample of Montgomery red clover, expressed in terms of biochanin A, was found to be in good agreement with that expected from concentrations of isoflavones determined from chemical analysis. A study was also made of p-hydroxyphenylacetic acid and the benzyl phenyl ketones related to the four isoflavones. These are products of chemical degradation of the isoflavones and were thought to be possible metabolic products of isoflavones in animals. None of these substances were found to have oestrogenic activity.