Changes in the Mutagenic and Estrogenic Activities of 17β-Estradiol after Treatment with Nitrite

Abstract

We determined the changes in the mutagenic and estrogenic activities of 17β-estradiol after a nitrite treatment. Nitrite-treated 17β-estradiol showed mutagenic activities toward Salmonella typhimurium strains TA 100 and TA 98. We confirmed that nitrite-treated 17β-estradiol generated radicals from the results of an analysis of electron spin resonance. By applying an instrumental analysis, we identified 2-nitro-17β-estradiol to have been formed in the reaction mixture. 2-Nitro-17β-estradiol did not exhibit mutagenic activities toward Salmonella typhimurium strains, suggesting that other mutagens might have been formed in the reaction mixture. The clastogenic properties of nitrite-treated 17β-estradiol and 2-nitro-17β-estradiol were analyzed by a micronucleus test with male ICR mice. Nitrite-treated 17β-estradiol and 2-nitro-17β-estradiol induced a significantly higher frequency of micronucleated reticulocytes in mice. The estrogenic activity of 2-nitro-17β-estradiol was found to be lower than that of 17β-estradiol. These data suggest that a daily oral intake of 17β-estradiol and nitrite might induce the formation of mutagenic compounds in our body.