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Reactivity of β‐carotene towards peroxyl radicals studied by laser flash and steady‐state photolysis
Author(s) -
Mortensen Alan,
Skibsted Leif H
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00382-2
Subject(s) - chemistry , flash photolysis , photochemistry , radical , reactivity (psychology) , hydrogen atom abstraction , photodissociation , cyclohexane , reaction rate constant , organic chemistry , kinetics , medicine , physics , alternative medicine , pathology , quantum mechanics
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 β‐carotene studied. Steady‐state photolysis experiments showed that alkyl, alkoxyl and alkylperoxyl radicals all react with β‐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 β‐carotene is hence a poor direct scavenger of peroxyl radicals. Scavenging of peroxyl radicals by β‐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 β‐carotene seem to be correlated with standard reduction potential.