Kinetic study of the quenching reaction of singlet oxygen by eight vegetable oils in solution

Kazuo Mukai, Ayaka Ohara, Junya Ito, Masayuki Hirata, Eri Kobayashi, Kiyotaka Nakagawa, Shin Ichi Nagaoka

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    3 Citations (Scopus)

    Abstract

    �A kinetic study of the reaction of singlet oxygen ( 1 O 2 ) with eight vegetable oils 1–8 containing different concentrations of tocopherols (Tocs) and tocotrienols (Toc-3s) was performed. The second-order rate constants (k Q ) for the reaction of 1 O 2 with vegetable oils 1–8 (rice bran, perilla, rape seed, safflower, grape seed, sesame, extra virgin olive, and olive oils) were measured in ethanol/chloroform/D 2 O (50:50:1, v/ v/v) solution at 35℃ using UV-vis spectrophotometry. Furthermore, comparisons of k Q values determined for the above oils 1-8 with the sum of the product {∑k Q AO-i [AO-i]/10 5 } of the k Q AO-i values obtained for each antioxidant (AO-i) and concentration (in mg/100 g) ([AO-i]/10 5 ) of AO-i (Tocs and Toc-3s) contained in the oils 1-8 were performed. The observed k Q values were not reproduced by the k Q values calculated using only the concentrations of the four Tocs and Toc-3s. These results suggest that the contribution of fatty acids contained in the oils 1-8 is also necessary to fully explain the k Q values. Recently, the second-order rate constants (k S ) for the reaction of aroxyl radical (ArO・) with the same vegetable oils 1–8 were measured in the same solvent at 25℃ using stopped-flow spectrophotometry (Ref. 23). The k S values obtained could be well explained as the sum of the product {Σ k S AO-i [AO-i]/10 5 } of the k S AO-i and the [AO-i]/10 5 of AO-i (Tocs and Toc-3s) contained in the vegetable oils.

    Original languageEnglish
    Pages (from-to)21-31
    Number of pages11
    JournalJournal of oleo science
    Volume68
    Issue number1
    DOIs
    Publication statusPublished - 2019

    Keywords

    • Antioxidant activity
    • Reaction rate
    • Singlet oxygen
    • Soac assay method
    • Tocopherol and tocotrienol
    • Vegetable oils

    ASJC Scopus subject areas

    • Chemistry(all)
    • Chemical Engineering(all)

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