Nohl H, Gille L
Institute of Pharmacology and Toxicology, Veterinary University Vienna, Austria.
Z Naturforsch C J Biosci. 1998 Mar-Apr;53(3-4):250-3. doi: 10.1515/znc-1998-3-415.
Ubiquinone and alpha-lipoic acid are natural constituents which are involved in mitochondrial energy metabolism. Their bioenergetic activities require redox-cycling. In the case of alpha-lipoic acid redox-cycling leads to dihydrolipoic acid which occurs in multienzyme complexes involved in the citric acid cycle while UQ recycles through semi- and divalently reduced ubiquinones in the respiratory chain. We have proved the validity of the concept about the antioxidant function of these natural compounds in their reduced form. Ubiquinol was found to interfere with lipid peroxidation of liposomal membranes being itself degradated by two consecutive oxidation steps. Dihydrolipoic acid was found to totally recycle ubiquinone to the antioxidant active divalently reduced form. In contrast to the antioxidative derived reaction products of ubiquinols which in turn promoted lipid peroxidation, the antioxidant derived reaction product of dihydrolipoic acid was the unreactive two electron oxidation product alpha-lipoic acid. Our experiments demonstrate the existence of an dihydrolipoic acid driven recycling of UQ to the antioxidative-active UQH2. The efficiency of the antioxidative capacity of the latter was found to be diminished through prooxidant activities of the antioxidant-derived metabolites.
泛醌和α-硫辛酸是参与线粒体能量代谢的天然成分。它们的生物能量活性需要氧化还原循环。就α-硫辛酸而言，氧化还原循环会生成二氢硫辛酸，其存在于参与柠檬酸循环的多酶复合物中，而泛醌则通过呼吸链中的半还原和二价还原泛醌进行循环。我们已经证明了这些天然化合物还原形式的抗氧化功能这一概念的有效性。发现泛醇会干扰脂质体膜的脂质过氧化，其自身会通过两个连续的氧化步骤降解。发现二氢硫辛酸能将泛醌完全循环至抗氧化活性的二价还原形式。与泛醇的抗氧化衍生反应产物相反，后者又促进脂质过氧化，而二氢硫辛酸的抗氧化衍生反应产物是无反应性的双电子氧化产物α-硫辛酸。我们的实验证明了存在由二氢硫辛酸驱动的泛醌向抗氧化活性泛醇的循环。发现后者的抗氧化能力效率会因抗氧化衍生代谢产物的促氧化活性而降低。
