ИСТИНА

The content of antioxidants in the biological material has important clinical implications, as it characterizes the ability of a living organism to resist oxidation processes associated with formation of free radicals. In present study we used a chemiluminescence method to evaluate antioxidant capacity, which was calculated on the basis of reducing light sum of chemiluminescence after adding antioxidants to the radical-producing system. Light sum of chemiluminescence represents the amount of free radicals generated in the system, and the light sum decrease after the addition of antioxidant reflects the amount of radicals scavenged by an antioxidant. Thus, the proposed method for determining the antioxidant capacity allows to estimate the amount of free radicals intercepted by the analyte. Number of trapped radicals depends not only on the concentration of antioxidant in the sample, but also on the stoichiometric ratio (antioxidant adeed / radical trapped). Moreover, biological samples may contain several antioxidants having different stoichiometric ratios of interaction with free radicals. We used a radical¬producing system consisting of horseradish peroxidase (4 nM), hydrogen peroxide (100 uM) and luminol (40 uM) dissolved in 20 mM phosphate buffer (pH 7,4). During 10 minutes of exposure, strong antioxidants (ascorbic acid) and antioxidants of intermediate strenght (quercetin) present in samples were fully utilized. In this study, 4 plant object were used (infusion of dried raspberry fruit, decoctions of dried fruits of mountain ash, hawthorn and wild rose). For every sample, we calculated TAoC in equivalents of quercetin (mg% quercetin): light sum changes were recalculated in light sum change equivalents obtained for quercetin. The technique is more simple, express and cheap than existing chemical methods. This technique is adequate to study objects that contain a mixture of antioxidants. Along with the mathematical modeling of chemiluminescence kinetics, this technique provides the possibility to determine antioxidant activity of each particular antioxidant in the system.