Oxidative metabolites of diethylstilbestrol in the fetal Syrian golden hamster.

14C-Diethylstilbestrol was administered orally, intraperitoneally, and intrafetally to 15-day pregnant hamsters at a dose of 20 mg/kg body weight, and the radioactivity was determined in the fetus, placenta, and maternal liver after 6 hours. Significant amounts of radioactivity were found in these tissues in every case, indicating maternal-fetal and fetal-maternal transfer of diethylstilbestrol. Part of the radioactivity found in the tissues could not be extracted even after excessive washing. This implied the presence of reactive metabolites. In the fetal and placental extracts, eight oxidative metabolites of diethylstilbestrol were identified by mass fragmentography as hydroxy- and methoxy-derivatives of diethylstilbestrol, pseudodiethylstilbestrol, and dienestrol. The presence of oxidative metabolites in the hamster fetus and the covalent binding to tissue macromolecules are possibly associated with the fetotoxic effects of diethylstilbestrol.