Skip to the content

Generation of superoxide and singlet oxygen from α-tocopherolquinone and analogues.

Crisostomo, AG, Moreno, RB, Navaratnam, S, Wilkinson, JA and Bisby, RH 2007, 'Generation of superoxide and singlet oxygen from α-tocopherolquinone and analogues.' , Free Radical Research, 41 (6) , pp. 730-737.

[img]
Preview
PDF
Download (220kB) | Preview

    Abstract

    Three potential routes to generation of reactive oxygen species from a tocopherolquinone have been identified. The quinone of the water-soluble vitamin E analogue Trolox C (Trol-Q) is reduced by hydrated electron and isopropanol a hydroxyalkyl radical, and the resulting semiquinone reacts with molecular oxygen to form superoxide with a second order rate constant of 1.3 x 108 dm3 mol-1 s-1, illustrating the potential for redox cycling. Illumination (UV-A, 355 nm) of the quinone of 2,2,5,7,8-pentamethyl-6-hydroxychromanol (PMHC-Q) leads to a reactive short-lived (ca 10-6 s) triplet state, able to oxidise tryptophan with a second order rate constant greater than 109 dm3 mol-1 s-1. The triplet states of these quinones sensitize singlet oxygen formation with quantum yields of about 0.8. Such potentially damaging reactions of a tocopherolquinone may in part account for the recent findings that high levels of dietary vitamin E supplementation lack any beneficial effect and may lead to slightly enhanced levels of overall mortality.

    Item Type: Article
    Schools: Colleges and Schools > College of Science & Technology
    Colleges and Schools > College of Science & Technology > School of Environment and Life Sciences
    Colleges and Schools > College of Science & Technology > School of Environment and Life Sciences > Biomedical Research Centre
    Journal or Publication Title: Free Radical Research
    Publisher: T
    Refereed: No
    ISSN: 1071-5762
    Related URLs:
    Depositing User: H Kenna
    Date Deposited: 26 Jul 2007 15:58
    Last Modified: 20 Aug 2013 16:46
    URI: http://usir.salford.ac.uk/id/eprint/261

    Actions (login required)

    Edit record (repository staff only)

    Downloads per month over past year

    View more statistics