ESR studies of ascorbic acid-dependent recycling of the vitamin E homologue Trolox by coenzyme Q0 in murine skin homogenates.
The recycling of Trolox, a water-soluble vitamin E homologue, by coenzyme Q0 (CoQ0) during Cu2+-initiated oxidation of ascorbate in mouse skin homogenates was investigated using electron spin resonance (ESR) spectroscopy. In a mixture containing CoQ0, Cu2+ and mouse skin homogenates, the ESR signal of CoQ0 semiquinone radical (CoQ0*-) appeared and declined with time; addition of Trolox accelerated the CoQ0*- signal decay. Only after the disappearance of the CoQ0*- signal was the appearance of the Trolox phenoxyl radical signal observed. In addition, the lifetime of the CoQ0*- signal and the length of the lag period during which the Trolox radical ESR signal could not be detected were dependent on the presence of Trolox, CoQ0 or Cu2+. The results suggest that CoQ0*-, formed by the interaction between CoQ0 and endogenous ascorbic acid (AscH-) in skin homogenates, regenerates Trolox from its phenoxyl radical.
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Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
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D000818:Animals; D000975:Antioxidants / Q000493:pharmacokinetics*; D001205:Ascorbic Acid / Q000378:metabolism*; D002839:Chromans / Q000493:pharmacokinetics*; D003067:Coenzymes; D003300:Copper / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008812:Mice, Hairless; D008956:Models, Chemical; D012867:Skin / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000378:metabolism
D000975:Antioxidants; D002839:Chromans; D003067:Coenzymes; D005609:Free Radicals; D014451:Ubiquinone; D003300:Copper; C024989:coenzyme Q10; D001205:Ascorbic Acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid