Metabolism of androgens and estrogens by human fecal microorganisms

Abstract Modifications of androgens and estrogens were observed in incubations with mixed human fecal cultures. Both oxidative and reductive reactions have been shown to occur. Moreover, the fecal concentration determines the types of metabolites formed. Analysis of reactions of high fecal concentration resulted in the identification of products formed by reduction. 4-ene-3-ketosteroids were reduced in ring A. 5β-3-ketosteroids were reduced to 5β-3-hydroxysteroids. 17-keto-androgens and estrogens were reduced to 17β-hydroxy products. Analysis of low fecal concentration incubations resulted in products formed by oxidation and by cleavage of conjugated steroids. 5β-androstane-3,17-dione was found to be converted to 4-androstene-3,17-dione. And 17β-hydroxysteroids were converted to 17-oxosteroids. Furthermore the estrogen conjugates estrone-3-sulfate and estradiol-3-glucuronide were hydrolyzed to form estrone and estradiol respectively. A number of the reductive reactions occurred under aerobic conditions. This may reflect the ability of the fecal extract to lower the oxidation-reduction potential of the reaction mixture. The androgen and estrogen metabolites varied depending on the concentration of feces and the availability of oxidizing agents, such as phenazine methosulfate or menadione