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J. Qu, I. Washington; Red Light Induced Antioxidative Protection in Retina. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5937.
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Oxidative damage is believed to be involved in the pathogenesis of age related diseases of the eye including macular degeneration and cataract. Ubiquinone is a fat-soluble endogenous quinone that is found in mitochondria. The efficient reduction of ubiquinone to ubiquinol is essential for ATP synthesis and the formed ubiquinol can acts as a powerful antioxidant by scavenging lipid peroxyl radicals.The purpose of this study was to determine whether red light could be used to convert ubiquinone to ubiquinol in the eye to provide a mechanism for antioxidative protection.
Bovine retina was incubated with Vitamin C, the chlorophyll derivative pyropheophorbide-a and exposed to red light centered at 660 nm. Subsequently, ubiquinol/ubiquinone was isolated and quantified by use of methanol precipitation and heptane extraction followed by high performance liquid chromatography (HPLC) through the use of reference standard calibration curves of concentration versus HPLC peak area and comparing retention times for known quantities of ubiquinone/ubiquinol. The ubiquinol/ubiquinone ratio of light exposed retina was compared to that of retina treated as above, however in the absence of red light or pyropheophorbide-a (controls). Lipid peroxidation, a marker of oxidative stress, was evaluated by the thiobarbituric acid assay in the above described treated and control groups.
High levels of ubiquinone (1.9 µM/g wet tissue) were found in the bovine retina. The ubiquinol/ubiquinone ratio for untreated retinas was found to be 0.16 ± 0.02. Upon exposure to light for 2 hours, 55% of the total ubiquinone was converted to ubiquinol to give a final ubiquinol/ubiquinone ratio of 0.51 ± 0.08. The thiobarbituric acid assay showed no increase in lipid peroxidation for control and treated groups (p=0.20, student’s t-test).
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