Quantum chemical evaluation of the role of HO2• radicals in the kinetics of the methyl linoleate oxidation in micelles

The process of lipid peroxidation (LPO) plays an extremely important role in the human body due to the fact that its uncontrolled development can lead to oxidative stress and a number of serious diseases. The traditional approach to the analysis of the mechanism and kinetics of LPO is based on the well-known ideas that emerged from the study of radical-chain oxidation of hydrocarbons in a homogeneous medium. However, the distinctive feature of LPO is that this process is heterogeneous and the processes of diffusion of active intermediates between the aqueous and hydrocarbon phases should play a significant role in it. In the present work, an attempt has been made to theoretically estimate the contribution of these processes to the oxidation kinetics of model substances used in practice in the study of LPO. In the course of the calculations, a quantum chemical and kinetic analysis of the role of hydroperoxyl radical in the radical-chain mechanism of oxidation of methyl linoleate in micelles was carried out. The molecular dynamics method shows the important role of changing the dynamic rigidity of a hydrocarbon fragment of a chain during the formation of a peroxyl radical and hydroperoxyl group during the oxidation of a substrate in a heterogeneous medium. Quantum chemical calculations of the thermodynamics of reactions involving HO2 center dot radicals and the effects of their solvation made it possible to estimate the kinetic constants of the reaction rates. Using kinetic modeling, their relative contribution to the oxidation kinetics was revealed. In this case, it is possible to explain a number of anomalies associated with the oxidation of polyunsaturated fatty acids and their esters in micelles compared with their oxidation in a homogeneous hydrocarbon medium.