AN EXPERIMENTAL-MODEL FOR THE EVALUATION OF LIPID-PEROXIDATION IN LENS MEMBRANES

Lipid peroxidation has been associated with a number of specific manif estations related both to lens aging and cataract development. The ass essment of the effect of various naturally occurring prooxidants as we ll as the development of antioxidant strategies has often been limited by the lack of appropriate and simple experimental models. In this st udy we discuss the adaptation of a method based on the incorporation o f a fluorescent probe (parinaric acid) into biological membranes to mo nitor early stages of lipid peroxidation. After establishing the appro priate conditions, the method can be successfully applied to study per oxidation in bovine lens membranes, allowing for the evaluation of the effect of several free radical generating systems, including the foll owing metal-dependent initiators: ascorbate/iron, hydrogen peroxide/co pper and cumene hydroperoxide/copper. The inhibitory effect of the che lating agent diethylenetriaminepenta-acetic acid and the competitive h ydroxyl radical scavenger sorbitol, was consistently observed on parin aric acid degradation, on hydroxyl radical yield and on the amount of thiobarbituric acid reactive material produced. It could be shown that oxidative degradation of the probe gives direct information on lens m embrane susceptibility to a specific peroxidation system. Parinaric ac id can therefore be used as an efficient oxidation probe to evaluate o xidative damage inflicted to lens membranes by different systems, allo wing also the evaluation of the antioxidant effect of various drugs in cluding those with potential anticataractogenic effect.