β-carotene as an interceptor of free radicals

Kinetics of nonenzymic and nonphotochemical oxidation of β-carotene have been studied. The rate constants for the reactions of β-carotene with initiator-derived C-centered and peroxyl radicals in solution were measured as not, vert, similar 104 and 5 × 105 − 1 × 104 M−1s−1, respectively. β-Carotene-derived free radicals have been shown to be less reactive toward polyene than initiator-derived radicals. This suggests that β-carotene might behave as an interceptor of free radical species regardless of the oxygen pressure in the environment. The mechanism for β-carotene oxidation covering the main pathways for formation, transformation, and decay of free radicals has been formulated. In combination with experimental kinetic parameters and their temperature correlation, computer modeling has been used to solve the reaction kinetics numerically. The model proposed enables analysis of the kinetics of β-carotene consumption and oxygen uptake under various conditions, as well as the influence of β-carotene on oxidation of polyunsaturated fatty acids and their esters.