Mechanism of chain termination in lipid peroxidation by carotenes

A theoretical study

Jian Jhih Guo, Ching-Han Hu

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The reaction mechanism of carotenes (CARs) in chain termination against lipid peroxidation was studied using density functional theory. In the presence of peroxide (ROO), the reaction barrier for its addition to CAR to form ROO-CAR is smaller than those for its hydrogen abstractions from CAR and linoleic acid (LAH), respectively. In contrast, the reaction barriers for the O2 additions of the carbon-centered radicals are ordered as ROO-CAR > CAR(-H) > LA. Thus, the chain-termination function of CAR is best demonstrated by trapping the addition radical and suppressing O2 addition. For either the ROO-CAR or CAR(-H) radicals, β-carotene has noticeably higher O2 addition barriers than those of their lycopene counterparts. The reaction barrier for the rearrangement of ROO-CAR into RO + epoxide is much smaller than that for the formation of cyclic ether and is comparable to that of O2 addition. Since RO has a stronger tendency toward hydrogen abstraction than ROO, the rearrangement of the addition adduct has to be recognized as an important factor while evaluating the chain-termination potency of a molecule. The overall reaction energy profile reveals that the protective function of CAR is mostly exhibited via formation of the addition adduct. Comparatively, β-carotene is a more potent antiradical agent than lycopene against peroxide-initiated lipid peroxidation.

Original languageEnglish
Pages (from-to)16948-16958
Number of pages11
JournalJournal of Physical Chemistry B
Volume114
Issue number50
DOIs
Publication statusPublished - 2010 Dec 23

Fingerprint

carotene
Carotenoids
Lipids
lipids
peroxides
adducts
Hydrogen
Cyclic Ethers
Linoleic acid
epoxy compounds
Lipid Peroxides
Epoxy Compounds
Peroxides
Linoleic Acid
hydrogen
Density functional theory
Ethers
ethers

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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abstract = "The reaction mechanism of carotenes (CARs) in chain termination against lipid peroxidation was studied using density functional theory. In the presence of peroxide (ROO•), the reaction barrier for its addition to CAR to form ROO-CAR• is smaller than those for its hydrogen abstractions from CAR and linoleic acid (LAH), respectively. In contrast, the reaction barriers for the O2 additions of the carbon-centered radicals are ordered as ROO-CAR• > CAR(-H)• > LA•. Thus, the chain-termination function of CAR is best demonstrated by trapping the addition radical and suppressing O2 addition. For either the ROO-CAR• or CAR(-H)• radicals, β-carotene has noticeably higher O2 addition barriers than those of their lycopene counterparts. The reaction barrier for the rearrangement of ROO-CAR• into RO• + epoxide is much smaller than that for the formation of cyclic ether and is comparable to that of O2 addition. Since RO• has a stronger tendency toward hydrogen abstraction than ROO•, the rearrangement of the addition adduct has to be recognized as an important factor while evaluating the chain-termination potency of a molecule. The overall reaction energy profile reveals that the protective function of CAR is mostly exhibited via formation of the addition adduct. Comparatively, β-carotene is a more potent antiradical agent than lycopene against peroxide-initiated lipid peroxidation.",
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Mechanism of chain termination in lipid peroxidation by carotenes : A theoretical study. / Guo, Jian Jhih; Hu, Ching-Han.

In: Journal of Physical Chemistry B, Vol. 114, No. 50, 23.12.2010, p. 16948-16958.

Research output: Contribution to journalArticle

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