The antioxidant effect of ubiquinone and combined therapy on mitochondrial function in blood cells in non-proliferative diabetic retinopathy: A randomized, double-blind, phase IIa, placebo-controlled study

Objectives: To evaluate the effect of ubiquinone and combined antioxidant therapy on mitochondrial function in non-proliferative diabetic retinopathy (NPDR) in a randomized, double-blind, phase IIa, placebo-controlled, clinical trial. Three groups of 20 patients were formed: Group 1, ubiquinone; Group 2, combined therapy; and Group 3, placebo (one daily dose for 6 months). Methods: Fluidity of the submitochondrial membrane in platelets was determined by examining intensity of fluorescence between the monomer (I-m) and excimer (I-e). Hydrolytic activity of the mitochondrial F0F1-ATPase was evaluated with the spectrophotometric method. Results: Normal, baseline submitochondrial membrane fluidity, 0.24 +/- 0.01 I-e/I-m, was significantly diminished in the three study groups vs. normal values (P < 0.0001); placebo, 0.14 +/- 0.01 I-e/I-m; ubiquinone, 0.14 +/- 0.01 I-e/I-m; and combined therapy, 0.13 +/- 0.00 I-e/I-m. Afterward, it increased significantly (P < 0.0001), the ubiquinone group 0.22 +/- 0.01 I-e/I-m, combined therapy group, 0.19 +/- 0.01 I-e/I-m; with no changes the placebo group. Baseline hydrolytic activity of the F0F1-ATPase enzyme increased in the three study groups vs. normal values (184.50 +/- 7.84 nmol PO4), placebo, 304.12 +/- 22.83 nmol PO4 (P < 0.002); ubiquinone, 312.41 +/- 25.63 nmol PO4 (P < 0.009); and combined therapy, 371.28 +/- 33.50 nmol PO4 (P < 0.002). Afterward, a significant decrease the enzymatic activity: ubiquinone, 213.25 +/- 14.19 nmol PO4 (P < 0.001); and combined therapy, 225.55 +/- 14.48 nmol PO4 (P < 0.0001). Discussion: Mitochondrial dysfunction significantly improved in groups of NPDR patients treated with antioxidants.