Coenzyme Q10 and α-lipoic acid: antioxidant and pro-oxidant effects in plasma and peripheral blood lymphocytes of supplemented subjects.

Reactive oxygen species not only cause damage but also have a physiological role in the protection against pathogens and in cell signalling. Mitochondrial nutrients, such as coenzyme Q10 and α-lipoic acid, beside their acknowledged antioxidant activities, show interesting features in relation to their redox state and consequent biological activity. In this study, we tested whether oral supplementation with 200 mg/day of coenzyme Q10 alone or in association with 200 mg/die of α-lipoic acid for 15 days on 16 healthy subjects was able to modulate the oxidative status into different compartments (plasma and cells), in basal condition and following an oxidative insult in peripheral blood lymphocytes exposed in vitro to H2O2. Data have shown that tested compounds produced antioxidant and bioenergetic effects improving oxidative status of the lipid compartment and mitochondrial functionality in peripheral blood lymphocytes. Simultaneously, an increased intracellular reactive oxygen species level was observed, although they did not lead to enhanced DNA oxidative damage. Coenzyme Q10 and α-lipoic acid produced beneficial effects also steering intracellular redox poise toward a pro-oxidant environment. In contrast with other antioxidant molecules, pro-oxidant activities of tested mitochondrial nutrients and consequent oxidant mediated signalling, could have important implications in promoting adaptive response to oxidative stress.

Effect of coenzyme Q10 administration on endothelial function and extracellular superoxide dismutase in patients with ischaemic heart disease: a double-blind, randomized controlled study.

AIMS: This randomized controlled study was designed to determine whether oral coenzyme Q(10) (CoQ(10)) supplementation (100 mg tid) was able to improve extracellular superoxide dismutase (ecSOD) activity and endothelium-dependent (ED) vasodilation in patients with coronary artery disease (CAD). ecSOD, a major antioxidant enzyme system of the vessel wall, is reduced in patients with CAD. Moreover, there is a strong correlation between endothelium-bound ecSOD and the ED dilation of conduit arteries. CoQ(10) has been recently shown to improve the ED relaxation in diabetic patients. METHODS AND RESULTS: Thirty-eight CAD patients (33 M/5 F, mean age 55 +/- 4 years, ejection fraction 57.5 +/- 8%) were randomized into two groups. One group (n = 19) received CoQ(10) orally at doses of 300 mg/day for 1 month, whereas the other group received a placebo. On entry and after 1 month, all patients underwent brachial artery ED assessment, cardiopulmonary exercise test, and the measurement of endothelium-bound ecSOD activity. A total of 33 patients completed the study. ecSOD, ED relaxation, as well as peak VO(2) and O(2) pulse increases in the CoQ(10)-treated group were statistically greater vs. the variations in the placebo group. In particular, improvements elicited by CoQ(10) supplementation were remarkable in subjects presenting low initial endothelium-bound ecSOD and thus more prone to oxidative stress. CONCLUSION: Improvements in the ED relaxation and endothelium-bound ecSOD activity might be related to CoQ(10) capability of enhancing endothelial functionality by counteracting nitric oxide oxidation. The enhancement of peak VO(2) and of O(2) pulse is likely due to the bioenergetic effect of CoQ(10); on the other end, the improved VO(2) could also depend on the observed enhanced peripheral endothelial function.

Coenzyme Q10 and exercise training in chronic heart failure.

AIMS: There is evidence that plasma coenzyme Q(10) (CoQ(10)) levels decrease in patients with advanced chronic heart failure (CHF). However, it is not known whether oral CoQ(10) supplementation may improve cardiocirculatory efficiency and endothelial function in patients with CHF. METHODS AND RESULTS: We studied 23 patients in NYHA class II and III (20 men, three women, mean age 59+/-9 years) with stable CHF secondary to ischaemic heart disease [ejection fraction 37+/-7%], using a double-blind, placebo-controlled cross-over design. Patients were assigned to each of the following treatments: oral CoQ(10) (100 mg tid), CoQ(10) plus supervised exercise training (ET) (60% of peak VO(2), five times a week), placebo, and placebo plus ET. Each phase lasted 4 weeks. Both peak VO(2) and endothelium-dependent dilation of the brachial artery (EDDBA) improved significantly after CoQ(10) and after ET as compared with placebo. CoQ(10) main effect was: peak VO(2)+9%, EDDBA +38%, systolic wall thickening score index (SWTI) -12%; ET produced comparable effects. CoQ(10) supplementation resulted in a four-fold increase in plasma CoQ(10) level, whereas the combination with ET further increased it. No side effects were reported with CoQ(10). CONCLUSIONS: Oral CoQ(10) improves functional capacity, endothelial function, and LV contractility in CHF without any side effects. The combination of CoQ(10) and ET resulted in higher plasma CoQ(10) levels and more pronounced effects on all the abovementioned parameters. However, significant synergistic effect of CoQ(10) with ET was observed only for peak SWTI suggesting that ET amplifies the already described effect of CoQ(10) on contractility of dysfunctional myocardium.