A technical approach to the evaluation of glucose oxidation: implications for diabetic cataract

Oxidative stress has recently been involved in a number of diseases including development of diabetic cataract. If hyperglycemia is the relevant factor in diabetes, then it is reasonable to assume that under physiological conditions glucose may be toxic. The mechanisms involved in such a type of glucose 'toxicity' are still poorly understood but may involve glucose autoxidation. In this study we discuss a new methodological approach to the evaluation of glucose-induced oxidative damage to bovine lens membranes. The method is based on the incorporation of a fluorescent probe (parinaric acid) into lens membranes. The oxidative degradation of the probe is evaluated by monitoring its fluorescence decrease. It was possible to show that glucose may induce oxidative damage in the presence of trace amounts of transition metals. Furthermore, the data obtained by monitoring oxidative degradation of parinaric acid could be related to the amount of thiobarbituric acid-reactive substances formed under identical periods of time. The technique was shown to be reproducible, straightforward and highly sensitive as compared to other classical methods. Moreover, this methodological approach allows not only the evaluation of the extension of oxidative stress inflicted upon lens membranes but also the evaluation of the antioxidant effect of various compounds including some drugs with a potential anticataractogenic effect.