Study of Influence of Free Radical Species on Antioxidant Activity of Selected 1,2,4-Triazole-3-thiones

The free radical scavenging potency of four 1,2,4-triazole-3-thione compounds towards ten chosen radicals was investigated. The thermodynamic parameters, Gibbs free energies of reactions and reaction enthalpies, were used to determine the most probable mechanism of action. The results indicated that the favourable mechanism of antiradical action was dependent both on the polarity of solvents and a nature of free radical species. The results suggested that Sequential Proton Loss Electron Transfer (SPLET) is the most probable for reaction in benzene, while Hydrogen Atom Transfer (HAT) was favorized for reaction occurring in methanol. The constant competition between these mechanisms of antioxidative action was present. The molecular docking study, obtained for parent molecules of chosen 1,2,4-triazole-3-thiones compounds and their corresponding anionic species, showed their inhibitory nature against histidine kinase inhibitor Sda. Except in the case of compound 4 a, all the anionic species (4 d-4 h) showed the lower inhibition constants, indicating better inhibition potency of Sda, than corresponding parent molecules.