Reactivity of β‐carotene towards peroxyl radicals studied by laser flash and steady‐state photolysis

作者：Alan Mortensen, Leif Horsfelt Skibsted · 发表于：FEBS Letters · 年份：1998 · DOI：10.1016/s0014-5793(98)00382-2 · 被引用次数：67 · 研究领域：Free Radicals and Antioxidants、Antioxidant Activity and Oxidative Stress、Photochemistry and Electron Transfer Studies

Peroxyl radicals, as model for peroxyl radicals formed during autoxidation of lipids, have been generated in three solvent systems (cyclohexane, tetrahydrofuran and tert-butanol/water) by steady-state and laser flash photolysis, and their reaction with beta-carotene studied. Steady-state photolysis experiments showed that alkyl, alkoxyl and alkylperoxyl radicals all react with beta-carotene. However, laser flash photolysis experiments indicated that the reaction with peroxyl radicals (second-order rate constant estimated to be less than 10(6) M(-1) s(-1)) is slower than with alkyl and alkoxyl radicals, and that beta-carotene is hence a poor direct scavenger of peroxyl radicals. Scavenging of peroxyl radicals by beta-carotene is suggested not to proceed via electron transfer but rather by adduct formation and/or hydrogen abstraction. For different phenoxyl radicals, differences in reactivity towards beta-carotene seem to be correlated with standard reduction potential.