  Antioxidant capacity of garlic has been attributed to organic sulfur
compounds such us allyl methyl disulfide. Using quantum chemical calculations
at B3LYP/6-31+G (d) and G3MP2B3/6-31+G (d) levels of theory, we study three
possible oxidation reactions of this compound against hydrogen peroxide, a
reactive oxygen species, from a thermodynamic point of view. Because these
reactions are supposed to occur in biological media, solvent effect was taken
into consideration. Oxidation over the double bond that leads to the formation
of an epoxide is more thermodynamically feasible, limiting the antioxidant
capacity of this compound.
