Theoretical elucidation of the antioxidant mechanism of 1,3-dihydro-1-methyl-2H-imidazole-2-selenol (MSeI)

Theoretical calculations by means of density functional theory (DFT) at the B3LYP/6-31G(d) level have been performed to elucidate the antioxidant mechanism of 1,3-dihydro-1-methyl-2H-imidazole-2-selenol (MSeI) at the molecular level. The present detailed computational study of individual steps of the mechanism provides energetics and structures of all the intermediates and transition states. DFT results suggest a highly synchronous stepwise mechanism wherein the nucleophilic attack of thiol at the sulfur atom in selenyl sulfide (TS VII-VIII) is found to be the rate-determining step, which initiates the catalytic regeneration of selenol. The current computational studies are in excellent agreement with the mechanism proposed earlier.