RADICAL INTERMEDIATES DURING THE OXIDATION OF NITROPROPANES - THE FORMATION OF NO2 FROM 2-NITROPROPANE, ITS REACTIVITY WITH NUCLEOSIDES, AND IMPLICATIONS FOR THE GENOTOXICITY OF 2-NITROPROPANE

The chemistry of the nonenzymatic oxidation of the rat liver carcinogen, 2-nitropropane, and its anionic form, propane-2-nitronate, was investigated using pulse radiolysis and EPR/spin trapping with 3,5-dibromo-4-nitrosobenzenesulfonic acid as the trapping agent. The results suggest that, following initial oxidation to a secondary alkyl radical, propane-2-nitronate is effectively degraded in a peroxidative chain reaction with the intermediary formation of peroxyl and NO2. radicals. The latter radical was shown to react appreciably fast with ribonucleosides, deoxyribonucleosides, and guanosine nucleotides. It is proposed that nonenzymatic formation of NO2. radicals after enzymatic oxidation of propane-2-nitronate to the corresponding secondary alkyl radical accounts for the induction of DNA damage observed after exposure of rats to 2-nitropropane.