Participation of the pyrazine cation radical in the formation of mutagens in the reaction of glucose/glycine/creatinine.

Two classes of the free radical Maillard intermediates, the pyrazine cation radical and the carbon-centered radicals, are detected in the reaction of Glc (glucose)/Gly (glycine) by electron spin resonance and spin trapping technique. Profile of the generation of the pyrazine cation radical in the reaction with different ratios of the reactants was found to be similar to that of the formation of mutagens in the subsequent reaction with creatinine. By contrast, profile of the generation of the carbon-centered radicals was not consistent with that of the mutagen formation. Thiol antioxidants and unsaturated fatty acids (or their esters) effectively scavenged the pyrazine cation radical generated in the reaction of Glc/Gly, and inhibited the formation of the mutagens in the reaction of Glc/Gly and creatinine. Ethanol, a sulfide and a saturated fatty acid were not effective to scavenge the pyrazine cation radical and did not inhibit the mutagen formation. The pyrazine cation radical rather than the carbon-centered radicals may play an important role in the mutagen formation. Thiol antioxidants and unsaturated fatty acids can be evaluated as inhibitors of the pyrazine cation radical-derived formation of the mutagens.