Kinetic model for #beta#-carotene and lipid cooxidation

摘要

The kinetics of #beta#-carotene oxidation and the effect of oxygen partial pressure have been studied in n-decade solution. #beta#-Carotene exhibits high activity in the reactions with peroxyl and C-centered radicals. The reversible reaction of oxygen addition to #beta#-carotene-derived C-centered radicals (A), fast cross-disproportionation reactions of A and peroxyl polyene radicals (AO_2), and reactions of intermediate oxidation products with oxygen, resulting in free radical formation, are responsible for the pronounced effect of oxygen partial pressure on the kinetics of #beta#-carotene consumption and its antioxidant efficiency in lipid autoxidation.The mechanism of #beta#-carotene oxidation covering the main pathways for formation, transformation and decay of free radicals has been formulated. The rate constants for the elementary reactions of #beta#-carotene with initiator and #beta#-carotene derived C-centered and peroxyl radicals in solution were determined. Computer modeling has been used to solve numerically the reaction kinetics combining the experimental kinetic parameters and the literature data on the Corresponding rate constants. The model proposed enables analysis of the kinetics of #beta#-carotene consumption and oxygen uptake under various conditions as well as assessment of the influence of #beta#-carotene on oxidation of methyl linoleate and other organic compounds.