Effect of coenzyme Q10 intake on endogenous coenzyme Q content, mitochondrial electron transport chain, antioxidative defenses, and life span of mice

The main purpose of this study was to determine whether intake of coenzyme Q(10), which can potentially act as both an antioxidant and a prooxidant, has an impact on indicators of oxidative stress and the aging process. Mice were fed diets providing daily supplements of 0, 93, or 371 mg CoQ(10)/kg body weight, starting at 3.5 months of age. Effects on mitochondrial superoxide generation, activities of oxidoreductases, protein oxidative damage, glutathione redox state, and life span of male mice were determined. Amounts of CoQ(9) and CoQ(10), measured after 3.5 or 17.5 months of intake, in homogenates and mitochondria of liver, heart, kidney, skeletal muscle, and brain increased with the dosage and duration of CoQ(10) intake in all the tissues except brain. Activities of mitochondrial electron transport chain oxidoreductases, rates of mitochondrial O-2(-center dot) generation, state 3 respiration, carbonyl content, glutathione redox state of tissues, and activities of superoxide dismutase, catalase, and glutathione peroxidase, determined at 19 or 25 months of age, were unaffected by CoQ(10) administration. Life span studies, conducted on 50 mice in each group, showed that CoQ(10) administration bad no effect on mortality. Altogether, the results indicated that contrary to the historical view, supplemental intake of CoQ(10) elevates the endogenous content of both CoQ(9) and CoQ(10), but has no discernable effect on the main antioxidant defenses or prooxidant generation in most tissues, and has no impact on the life span of mice. (c) 2005 Elsevier Inc. All rights reserved.