Ferri E, Gattavecchia E, Feroci G, Battino M
Istituto di Scienze Chimiche, University of Bologna, Italy.
Mol Aspects Med. 1994;15 Suppl:s83-8. doi: 10.1016/0098-2997(94)90016-7.
The involvement of coenzyme Q (CoQ) as an antioxidant agent in several oxidative processes both in vitro and in vivo is nowadays pointed out by several biochemical and clinical studies, but the chemical mechanisms of this action are not yet unequivocally established. Electrochemistry provides very useful techniques for the analysis of the kinetics and thermodynamics, and mechanisms of chemical phenomena involving electron transfers, e.g. in the case of radical reactions. In the present study we used cyclic voltammetry to investigate the interactions between oxygen radicals and ubiquinone in aprotic medium, a condition similar to that existing in the biological membranes. The results obtained showed that ubiquinone is more easily reduced than oxygen, ruling out the possibility of an electron transfer from semiquinone to oxygen to produce superoxide radicals. On the contrary, it was demonstrated that fully reduced quinone is able to scavenge the superoxide radical, by reduction to peroxide ion, lowering actually the oxidative potential in the medium.
如今，多项生化和临床研究指出，辅酶Q（CoQ）作为抗氧化剂参与了体内外的多种氧化过程，但其作用的化学机制尚未明确确立。电化学为分析动力学、热力学以及涉及电子转移的化学现象（如自由基反应）的机制提供了非常有用的技术。在本研究中，我们使用循环伏安法来研究非质子介质中氧自由基与泛醌之间的相互作用，该条件类似于生物膜中的情况。所得结果表明，泛醌比氧更容易被还原，排除了半醌向氧进行电子转移以产生超氧自由基的可能性。相反，已证明完全还原的醌能够通过还原为过氧离子来清除超氧自由基，实际上降低了介质中的氧化电位。
