Reaction mechanisms of peroxyl and c-centered radicals with sulfhydryls

Abstract

Rate constants for reactions of a peroxyl (CCl₃OO·) and C-centered radicals, that is, phenyl (·C₆H₄CH₂COO⁻) and vinyl (uracil-5-yl), with an aromatic thiol (p-CH₃OC₆H₄SH) were measured over a pH range (3–12) to include ArSH and ArS⁻ forms. The pH dependence of these rate constants indicates that peroxyl radicals react by a redox mechanism while the C-centered radicals react by an H-atom transfer process. The different mechanisms encountered in the repair of various radicals suggest design features to be incorporated into antiagents, such as radioprotectors and anticarcinogens.