Thiophenols, Promising Scavengers of Peroxyl Radicals: Mechanisms and kinetics

Abstract

The activity of 12 thiophenols as primary antioxidants in aqueous solution has been studied using density functional theory. Twelve different substituted thiophenols were tested as peroxyl radicals scavengers. Single electron transfer (SET) and formal hydrogen transfer (FHT) were investigated. The SET mechanism was found to be the main mechanism, with rate constants that are close to the diffusion limit, which means that these thiophenolic compounds have the capacity to scavenge peroxyl radicals before they can damage biomolecules. All 12 thiophenolic compounds react faster with methylperoxyl than with hydroperoxyl radicals. In addition, it was found that pH plays an important role in the reactivity of these compounds. © 2019 Wiley Periodicals, Inc.

The radical scavenging activity of moracins: theoretical insights

“…In this study, the quantum mechanics based test for overall free radical scavenging activity (QM-ORSA) protocol with the solvation model density (SMD) method (for water and pentyl ethanoate solvents) were used to performed the kinetic calculations. 22,[29][30][31][32][33][34] The rate constant (k) was calculated by using the conventional transition state theory (TST) (at 298.15 K, 1 M standard state) according to the eqn (1) (details method in Table S1, SI †): [35][36][37][38][39][40] k ¼ sk…”

The antioxidant activity of natural diterpenes: theoretical insights

“…Hence, the HOOc radical scavenging in the physiological environments is calculated via the SET mechanism for the anion states and the FHT mechanism for the neutral states. 27 The overall rate constants (k overall ) were calculated according to the eqn (4) and (5) and the obtained results are shown in Table 4.…”

“…To gain more accurate values, the M06-2X/6-311++G(d,p) level of theory was used, which is currently among best methods to compute accurate kinetic parameters. 9,27 At this level of theory the most active compound 6 was analyzed and the obtained results are presented in Table 5. It was found that the HOOc radical scavenging of 6 in water (k overall ¼ 1.69 Â 10 8 M À1 s À1 ) is about 1857 times higher than that (k overall ¼ 9.40 Â 10 4 M À1 s À1 ) in pentyl ethanoate solvent.…”

Comparison of the scavenging capacities of phloroglucinol and 2,4,6-trihydroxypyridine towards HO˙ radical: a computational study

“…It should be pointed out that this methodology has been successfully applied in the scientic literature for the investigation of primary and relative antioxidative activities. 44,45,[47][48][49][50][51][52][53][54]…”