The free radical scavenging activity of Trolox was studied for aqueous and lipid environments using the Density Functional Theory. Several reaction mechanisms and free radicals of different chemical nature have been included in this study, as well as the influence of the pH. Trolox was found to be a powerful ˙OH and alkoxy scavenger, regardless of the conditions under which the reaction takes p...

We report experimental evidence for the formation of C(5)-hydroperoxyaldehydes (HPALDs) from 1,6-H-shift isomerizations in peroxy radicals formed from the hydroxyl radical (OH) oxidation of 2-methyl-1,3-butadiene (isoprene). At 295 K, the isomerization rate of isoprene peroxy radicals (ISO2•) relative to the rate of reaction of ISO2• + HO2 is k(isom)(295)/(k(ISO2•+HO2)(295)) = (1.2 ± 0.6) x 10(...

ion of the tertiary hydrogen atom by peroxy group located at A-position, viz., IO-AQJ IO-AQCJ is the lowest energy process among the H-transfer reactions involving any isooctane peroxy radicals. The activation barrier ΔH (TS-C1A) is as low as ca.17 kcal mol (16.74, 17.09, 16.95 kcal mol, correspondingly, at B3LYP/6-31G(d), G3MP2B3, and CBS-QB3 levels of theory in agreement with the unified para...

Both stable conformers, trans (T) and gauche (G), of the ethyl peroxy radical and its perdeutero analogue have been observed via cavity ringdown spectroscopy (CRDS) of the A2A'-X2A' ' electronic transition in the near-IR. Assignments of specific spectral lines to the electronic transition origin (T00), to observed vibrational hot bands, and to the COO bend and the O-O stretch vibrations are giv...

A potential energy surface for the system of a hydroperoxy radical and a water molecule is presented. The surface was sampled using constrained density functional theory optimizations performed at the B3LYP level of theory using a 6-311‡‡G(3df,3pd) basis set. The data points were ®tted to an analytical function based on a common 4-point model for water and a 5-point model for the peroxy radical...

We report vibrational and electronic spectra of the hydroxy-methyl-peroxy radical (HOCH2OO(•) or HMP), which was formed as the primary product of the reaction of the hydroperoxy radical, HO2(•), and formaldehyde, HCHO. The ν1 vibrational (OH stretch) spectrum and the à ← X̃ electronic spectrum of HMP were detected by infrared cavity ringdown spectroscopy (IR-CRDS), and assignments were verified ...

The first observation of a sharp, structured electronic spectrum for a fluorinated alkyl peroxy radical is reported using the technique of cavity ringdown spectroscopy (CRDS). The T00 value for the Ã2A′ − X̃2A′′ transition of CF3O2 has been determined to be 6656(3) cm−1; values for à state vibrational frequencies have also been determined. Initial kinetic observations on CF3O2 have been carried ...

The fact that the full extent of the function of the pineal gland has not yet been elucidated, has stimulated melatonin research worldwide. This review introduces melatonin's mechanism of action, direct and indirect antioxidant actions as well as the antioxidant properties of its metabolites, 6-hydroxymelatonin (6-OHM) and N-acetyl-N-formyl-5-methoxykynurenamine (AFMK). At present the mechanism...