A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
alpha-, gamma- and delta-Tocopherols as inhibitors of isomerization and decomposition of cis,trans methyl linoleate hydroperoxides
Tekijät: Makinen M, Kamal-Eldin A, Lampi AM, Hopia A
Kustantaja: WILEY-V C H VERLAG GMBH
Julkaisuvuosi: 2001
Lehti:: European Journal of Lipid Science and Technology
Tietokannassa oleva lehden nimi: EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
Lehden akronyymi: EUR J LIPID SCI TECH
Vuosikerta: 103
Numero: 5
Aloitussivu: 286
Lopetussivu: 291
Sivujen määrä: 6
ISSN: 1438-7697
DOI: https://doi.org/10.1002/1438-9312(200105)103:5<286::AID-EJLT286>3.3.CO;2-H
Tiivistelmä
The effects of alpha-, gamma- and delta -tocopherols on the stability and decomposition reactions of lipid hydroperoxides were studied. Isomerization and decomposition of cis,trans methyl linoleate hydroperoxides (cis,trans ML-OOH) in hexadecane at 40 degreesC were followed by high-performance liquid chromatography. Due to its higher hydrogen donating ability, alpha -tocopherol was more efficient than gamma- and delta -tocopherols in inhibiting the isomerization of cis,trans ML-OOH to trans,trans ML-OOH. alpha -Tocopherol stabilized hydroperoxides into the cis,trans configuration, whereas gamma- and delta -tocopherols allowed hydroperoxides to convert into trans, trans isomers. Thus, the biological importance of a-tocopherol as compared to other tocopherols may be partly due to its better efficacy in protecting the cis,trans configuration of hydroperoxides formed, for example, in the enzymatic oxidation of polyunsaturated fatty acids. The isomeric configuration of hydroperoxides has an impact on biological activities of further oxidation products of polyunsaturated fatty acids. Paradoxically, the order of activity of tocopherols with regard to hydroperoxide decomposition was different from that obtained for hydroperoxide isomerization. gamma- and delta -tocopherols were more efficient inhibitors of ML-OOH decomposition when compared to a-tocopherol. A loss of antioxidant efficiency, observed as the tocopherol concentration increased from 2 to 20 mM, was highest for a-tocopherol but was also evident for gamma- and delta -tocopherols. Thus, the differences in the relative effects of tocopherols at differing concentrations seem to result from a compromise between their radical scavenging efficiency and participation in side reactions of peroxidizing nature.
The effects of alpha-, gamma- and delta -tocopherols on the stability and decomposition reactions of lipid hydroperoxides were studied. Isomerization and decomposition of cis,trans methyl linoleate hydroperoxides (cis,trans ML-OOH) in hexadecane at 40 degreesC were followed by high-performance liquid chromatography. Due to its higher hydrogen donating ability, alpha -tocopherol was more efficient than gamma- and delta -tocopherols in inhibiting the isomerization of cis,trans ML-OOH to trans,trans ML-OOH. alpha -Tocopherol stabilized hydroperoxides into the cis,trans configuration, whereas gamma- and delta -tocopherols allowed hydroperoxides to convert into trans, trans isomers. Thus, the biological importance of a-tocopherol as compared to other tocopherols may be partly due to its better efficacy in protecting the cis,trans configuration of hydroperoxides formed, for example, in the enzymatic oxidation of polyunsaturated fatty acids. The isomeric configuration of hydroperoxides has an impact on biological activities of further oxidation products of polyunsaturated fatty acids. Paradoxically, the order of activity of tocopherols with regard to hydroperoxide decomposition was different from that obtained for hydroperoxide isomerization. gamma- and delta -tocopherols were more efficient inhibitors of ML-OOH decomposition when compared to a-tocopherol. A loss of antioxidant efficiency, observed as the tocopherol concentration increased from 2 to 20 mM, was highest for a-tocopherol but was also evident for gamma- and delta -tocopherols. Thus, the differences in the relative effects of tocopherols at differing concentrations seem to result from a compromise between their radical scavenging efficiency and participation in side reactions of peroxidizing nature.
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