The metabolism of [16−14C]oestrone in vitro

Abstract

Incubation of rat- and human-liver slices and mushroom tyrosinase with 16-C14-estrone results in the formation of water-soluble ether-insoluble metabolites, in high percentage yield, which do not appear on incubating estrone with placental tissue or blood. Cyanide, but not malonate, inhibits the formation of such estrone metabolites by liver slices and also the adsorption or incorporation of C14 by this tissue. The nature of the estrone-degradation products was investigated; liver probably forms non-steroidal estrogen metabolites which differ in part from those formed by mushroom tyrosinase. No radioactive CO2 was evolved during the incubation of C14-estrone with liver. Both liver and placenta are able to convert estrone into ether-soluble metabolites even in the presence of cyanide, and with placenta these were shown to differ from either 17[beta]-estradiol or estriol. The evidence in favor of estrone-degradation by initial attack in ring A is discussed.