DETERMINATION BY ENHANCED LUMINESCENCE TECHNIQUE OF LIVER ANTIOXIDANTCAPACITY

A simple approach to quantitative determination of antioxidant capacit y of rat liver homogenate is proposed. It consists of measuring chemil uminescence generated by a suitable system ''detector'' for . OH radic als produced from sodium perborate. The system generating the light si gnal contained luminol and compounds producing enhancement of light em ission, such as sodium benzoate and indophenol. Two different methods, utilizing the same technique of enhanced luminescence, were set up. I n a previous work, a parameter b, contained in the equation, which bes t describes the dependence of the intensity of light emission (E) on l iver homogenate concentration (C) (E = a . C/exp(b . C), was found to be related to the level of antioxidants in the homogenate. Therefore, in the first method, the light emission from several dilutions of both liver homogenates, and homogenate and antioxidant mixtures, stressed with sodium perborate, was detected by a luminometer. The best fitting of data to theoretical equation provided b values, which were introdu ced in a system of equations relating such values to the antioxidant c oncentration. The solution of above system supplied the antioxidant co ncentration in the homogenate in terms of the equivalent concentration of the antioxidant used. in the other method, evaluations of the anti oxidant capacity of liver homogenates were obtained by the determinati on of the ability of 10% homogenates to quench the light emission indu ced by either peroxidase or cytochrome c in comparison to the ability of antioxidant solutions. Both methods are able to evidence the decrea se of the antioxidant concentration of liver homogenates after oxidati ve stress with ter-butylhydroperoxide. The value of both concentration changes and standard errors indicates that the method using a standar d curve obtained with peroxidase, such as catalyst of radical reaction , and deferoxamine, such as antioxidant, is to be preferred.