An Esr Study of Nonenzymatic Reactions of Nitroso Compounds with Biological Reducing Agents

Abstract

The nonenzymatic reduction of nitrosobenzene (1), 2-nitroso-l-naphthol (II) and 2-nitroso-l-naphthol-4-sulfonic acid (III) with reducing agents such as NADPH, L-cysteine and N-acetyl-L-cysteine led to the formation of the corresponding hydronitroxide radicals, as confirmed with ESR spectroscopy. In addition to these radicals, a novel hydronitroxide radical, which was conjugated with GSH at the 4-position, was observed in the reaction of II or III with GSH. The formation of a hydronitroxide conjugated with GSH still retains the radical structure with its related redox chemistry. In this case, the formation of a GSH conjugate does not lead to the formation of chemically less reactive species.

Key Words:

• ESR
• free radicals
• nitrosobenzene
• glutathione conjugate
• GSH