Superoxide generation by 1-nitropyrene in rat lung microsomes.

1-Nitropyrene (1-NP) is a potent mutagen which has been found in diesel exhaust particulates and photocopy toners. 1-NP is known to undergo reduction and oxidation by mammalian enzymes. Research into the biological activity of 1-NP has concentrated on its possible mutagenic and carcinogenic properties. Because other nitro compounds, such as nitrofurantion, are reduced to a nitro anion radical which can react with molecular oxygen to produce superoxide, it was of interest to determine if 1-NP produced superoxide. This study used acetylated cytochrome c/superoxide dismutase as a detection system in a lung microsomal system. Results show that 1-NP catalyzes the formation of superoxide, that the reaction obeys Michaelis-Menten kinetics and that this reaction is saturable. The significance of this study is that 1-NP may have toxic effects which are related to oxidant stress.