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Updated: Aug 6, 2026

Assessment of Open Probability of the Mitochondrial Permeability Transition Pore in the Setting of Coenzyme Q Excess
Published on: June 1, 2022
Antioxidant and prooxidant properties of mitochondrial Coenzyme Q
Andrew M James1, Robin A J Smith, Michael P Murphy
1Medical Research Council Dunn Human Nutrition Unit, Cambridge, UK.
Abstract:
Coenzyme Q is both an essential electron carrier and an important antioxidant in the mitochondrial inner membrane. The reduced form, ubiquinol, decreases lipid peroxidation directly by acting as a chain breaking antioxidant and indirectly by recycling Vitamin E. The ubiquinone formed in preventing oxidative damage is reduced back to ubiquinol by the respiratory chain. As well as preventing lipid peroxidation, Coenzyme Q reacts with other reactive oxygen species, contributing to its effectiveness as an antioxidant. There is growing interest in using Coenzyme Q and related compounds therapeutically because mitochondrial oxidative damage contributes to degenerative diseases. Paradoxically, Coenzyme Q is also involved in superoxide production by the respiratory chain. To help understand how Coenzyme Q contributes to both mitochondrial oxidative damage and antioxidant defences, we have reviewed its antioxidant and prooxidant properties.
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