Theoretical study of the elimination reaction of hydrogen peroxide by Allyl-Methyl Sulfide and Diallyl-sulfide, two garlic compounds

MARIO GUILLERMO DIAZ; ESTEBAN G. VEGA-HISSI; MATIAS F. ANDRADA; JUAN C. GARRO MARTINEZ

San Luis

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

Universidad Nacional de San Luis

The organosulfide compounds are organic species that contain one or more sulfur atoms in its structure. The garlic (Allium sativum) have a large number of organosulfide compounds that show different properties. There is evidence of the antiviral, antibacterial, and antiparasitic activity of these compounds. In addition, these compounds decrease the cholesterol levels, inhibit platelet aggregation and tumor growth. Among them, allyl-methyl sulfide (AMS) and diallyl-methyl sulfide (DMS) show a special interest as antioxidant agents. The current investigations on antioxidant species that prevent the oxidative stress, are particularly centered on the reduction of the well known oxygen reactive species (ROS) such as superoxide anion, hydroxyl radical and hydrogen peroxide, that can cause biological damage.In this work, we carried out theoretical quantum studies of the thermodynamic and kinetic aspects of the elimination reaction of hydrogen peroxide by AMS and DMS. A conformational analysis and the calculation of Fukui functions allowed the selection of the initial structures of AMS and DMS and the target region where these organosulfide compounds can receive a nucleophilic attack by hydrogen peroxide, respectively. We analyzed three pathways: 1) attack at the sulfide atom through an oxidation reaction; 2) attack over the vinyl group carbon atoms, performing an epoxidation reaction and 3) attack over the vinyl carbon atoms by a hydrogenation reaction. Intrinsic reaction coordinate calculations (IRC) confirmed the transition states proposed and provided the energy profile of the each pathway.We found that the three reactions analyzed are thermodynamically feasible whereas the sulfur atom oxidation reaction is the pathway kinetically favored.