Generation of nitro radical anions of some 5-nitrofurans, and 2- and 5-nitroimidazoles by rat hepatocytes.

Nitrofurantoin, nifurtimox, nifuroxime, nitrofurazone, misonidazole, benznidazole, ronidazole, and ornidazole were reduced to their respective nitro radical anions by intact rat hepatocytes at pH 7.4. The nitrofurantoin radical anion and other nitro anion radicals generated inside these cells were detected with ESR spectroscopy. Broadening of the signals from nitrofurantoin anion radicals was accomplished with paramagnetic transition metals, implying that the radicals were outside the cell in the medium. Rat hepatocytes are well suited for in situ electron spin resonance investigations of free radical metabolites and represent a model for the as yet unobtained direct detection of free radical metabolites in liver.