OXIDATION AND RADICAL INTERMEDIATES ASSOCIATED WITH THE GLUTATHIONE CONJUGATION OF MUCOCHLORIC ACID

The inactivation of the drinking water mutagen mucochloric acid (RICA) by reduced glutathione (GSH) was linked to the formation of an MCA-GS H conjugate, a nonmutagen in the Salmonella typhimurium (TA100) plate incorporation assay. Anaerobic formation of MCA-GSH is found now to be associated with oxidized glutathione (GSSG) and unconverted MCA. The anaerobic reaction of GSH with MCA in the presence of the radical trap 2-methyl-2-nitrosopropane (tNB; ''tert-nitrosobutane'') gives rise to an electron paramagnetic resonance (EPR) resulting from the overlappi ng spectra of two radical adducts. The first species exhibited hyperfi ne coupling constants of a(N) = 13.65 G and a(beta)(H) = 0.73 G. The s econd radical adduct exhibited a three-line signal of a(N) = 12.8 G. T he first species is assigned to an adduct of the MCA radical because d euteration of MCA (5-deuterio-MCA) caused the beta-hydrogen hyperfine coupling to collapse. The second radical adduct is unaffected by the d euteration of MCA. Thus, the involvement of both GSSG and a carbon-cen tered MCA radical in the action of MCA on GSH is indicated.