Synthesis of novel mammalian metabolites of the isoflavonoid phytoestrogens daidzein and genistein.

The synthesis of novel mammalian metabolites of dietary isoflavones, dihy- drodaidzein (4',7-dihydroxyisoflavanone) 7,* dihydrogenistein (4',5,7-trihydroxy- isoflavanone) 9, 6'-hydroxy-O-demethylangolensin (1-(2,4,6-trihydroxypheny1)-2-(4- hydroxypheny1)propan-1 -one) 70, and cis and trans4',7-dihydroxyisoflavan-4-ols 7 7, 72 is described, and their characteristics by physical and chemical constants given for the first time. (P.S.E.B.M. 1998, Vol 2171 pidemiological studies reveal that foodstuffs contain- ing isoflavonoid phytoestrogens may reduce the risk E of certain hormone-dependent cancers such as breast, prostate and colon cancer (1-8). Vegetarian and semiveg- etarian diets, especially in some developing and Asian coun- tries, are rich in plant isoflavonoids (9). Legumes (soy, len- tils, various peas, beans, etc.), whole grains, vegetables, fruits, and berries are important ingredients responsible for the isoflavonoid content in those diets. Soy foods, in par- ticular, associated with a reduced risk of breast and prostate cancers in Japan (3), provide significant amounts of isofla- vones to the human diet. Various soy foods may contain approximately 0.1 mg-300 mg of isoflavones/lOOg. Soy- milk and soynuts, examples of nonfermented soy foods, have two to three times more isoflavones than fermented soy foods such as tempeh, bean paste, miso, and fermented beancurd (10). The major isoflavones in soybeans are the acylated isoflavone glycosides genistin, daidzin, and glyci- tin and their aglycones, genistein (4',5,7-trihydroxy- isoflavone) I and daidzein (4',7-dihydroxyisoflavone) 2 and glycitein (4',7-dihydroxy-6-methoxyisoflavone). Other