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

DIAZ, MARIO; VEGA HISSI, E.G.; ANDRADA, M.F.; GARRO MARTÍNEZ, J.C.

San Luis

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica (SAB); 2019

UNSL

The organosulfide compounds are organic species that contain one or more sulfur atomsin its structure. The garlic (Allium sativum) have a large number of organosulfidecompounds that show different properties. There is evidence of the antiviral,antibacterial, and antiparasitic activity of these compounds. In addition, thesecompounds decrease the cholesterol levels, inhibit platelet aggregation and tumorgrowth. Among them, allyl-methyl sulfide (AMS) and diallyl-methyl sulfide (DMS) show aspecial interest as antioxidant agents. The current investigations on antioxidant speciesthat prevent the oxidative stress, are particularly centered on the reduction of the wellknown oxygen reactive species (ROS) such as superoxide anion, hydroxyl radical andhydrogen peroxide, that can cause biological damage.In this work, we carried out theoretical quantum studies of the thermodynamic andkinetic aspects of the elimination reaction of hydrogen peroxide by AMS and DMS.A conformational analysis and the calculation of Fukui functions allowed the selection ofthe initial structures of AMS and DMS and the target region where these organosulfidecompounds can receive a nucleophilic attack by hydrogen peroxide, respectively. Weanalyzed 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 reactioncoordinate calculations (IRC) confirmed the transition states proposed and provided theenergy profile of the each pathway.We found that the three reactions analyzed are thermodynamically feasible whereas thesulfur atom oxidation reaction is the pathway kinetically favored.