ESR spin trapping investigation on peroxynitrite decomposition: no evidence for hydroxyl radical production.

The decomposition of peroxynitrite in the presence of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) generated 5,5-dimethylpyrrolidone-(2)-oxy-(1) (DMPOX) without formation of DMPO/OH. Formate enhanced the peroxynitrite decomposition but did not generate any detectable amount of formate-derived free radicals. Glutathione, cysteine, penicillamine, and ascorbate reacted with peroxynitrite to generate the corresponding thiyl and ascorbyl radicals. The results show that the decomposition of peroxynitrite did not generate any significant amount of OH radicals, and one-electron reduction of peroxynitrite by ascorbate may be one of the important peroxynitrite detoxification pathways.