Chain-breaking reactions against lipid peroxidation performed by carotenes, including β-carotene (β-CAR) and lycopene (LYC), have been studied using density functional theory. We chose linoleic acid (LAH) as the lipid model and examined two mechanisms: hydrogen abstraction and addition. Our computed reaction diagrams reveal that the addition mechanism is able to offer a larger extent of chain-breaking protection than hydrogen abstraction. In the case of hydrogen abstraction, the resulting carotene radical CAR(-H)' has a smaller O2 affinity than the linoleic acid radical (LȦ). Formation of the addition adduct radical ROO-CAṘ is energetically favorable, and it has an even smaller tendency to react with O2 than CAR(-H)̇. Comparatively, ROO-β-CAṘ is less likely to react with O2 than ROO-LYĊ. Both the hydrogen abstraction and addition radicals (CAR(-H)̇ and ROO-CAṘ) react readily with a second ROȮ radical via either hydrogen abstraction or addition.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry