Oxidation of acetaldehyde by peroxynitrite and hydrogen Peroxide/Iron(II). Production Of acetate, formate, and methyl radicals.

Production of free radicals from acetaldehyde oxidation by enzymes and cellular fractions is a well-known process. The toxic effects of acetaldehyde, however, are usually attributed to its reactions with biomolecules to produce adducts. Here, we demonstrate that hypothetical adducts produced from attack of acetaldehyde by two important biological oxidants, peroxynitrite and hydrogen peroxide, decompose to produce acetate, formate, and methyl radicals. Acetate, formate, nitrate, and nitrite were characterized and quantified by capillary electrophoresis. Radicals were detected and quantified by the EPR spectra produced in the presence of spin traps 3,5-dibromo-4-nitrosobenzenesulfonic acid and 5,5-dimethyl-1-pyrroline N-oxide. Kinetic studies and product analysis were performed at different pHs. The results demonstrate that production of methyl radicals during oxidation of acetaldehyde by hydrogen peroxide was strictly dependent on the presence of iron(II) and occurred via two routes. One involved acetaldeh...