Free radical derivatives of nitrogen heterocycles in livers of english sole ( Parophrys vetulus) with hepatic neoplasms and other liver lesions

Abstract

Free radicals of xenobiotics in liver microsomes of English sole ( Parophrys vetulus) with hepatic neoplasms and other liver lesions were shown to be N-oxyl derivatives of nitrogen heterocycles. The fish were obtained from the highly polluted Duwamish River in Seattle, Washington State. The chemical structures of the free radicals were elucidated primarily by electron paramagnetic resonance (EPR) spectroscopy. Carbazole-9-oxyl was identified and other N-oxyl derivatives of nitrogen heterocycles also appeared to be present. Evidence showing that English sole are capable of forming nitroxyl free radicals from nitrogen heterocycles was obtained when carbazole was administered via injection into the caudal vein: that is, EPR spectroscopy of bile and lyophilized liver microsomes showed the presence of carbazole-9-oxyl. The evidence for the formation of N-oxyl derivatives in the English sole liver is of interest in regard to the etiology of hepatic lesions in fish.