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 F(0)F(1)-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 F(0)F(1)-ATPase enzyme increased in the three study groups vs. normal values (184.50 ± 7.84 nmol PO(4)), placebo, 304.12 ± 22.83 nmol PO(4) (P < 0.002); ubiquinone, 312.41 ± 25.63 nmol PO(4) (P < 0.009); and combined therapy, 371.28 ± 33.50 nmol PO(4) (P < 0.002). Afterward, a significant decrease the enzymatic activity: ubiquinone, 213.25 ± 14.19 nmol PO(4) (P < 0.001); and combined therapy, 225.55 ± 14.48 nmol PO(4) (P < 0.0001). Discussion: Mitochondrial dysfunction significantly improved in groups of NPDR patients treated with antioxidants.