Assessment of Oxidative and Antioxidant Capacity of Biological Substrates by Chemiluminescence Induced by Fenton Reaction

The aim of the investigation was to analyze the association between the ability of the substrate to oxidation and antioxidant activity according to the results of calculating the kinetics of chemiluminescence induced by Fenton reaction. Materials and Methods. The chemiluminescence induced by Fenton reaction was measured with the help of BKhL-07 biochemiluminometer (Russia) with 10-15 repetitions. The registration time was 30 s. The following reagents were used for Fenton reaction: solution of FeSO4 (10(-3) mol/L in the acid medium, pH=2), solution of hydrogen peroxide (10(-3) and 10(-1) mol/L). The chemiluminescence of albumin, hemoglobin, mixture of albumin and hemoglobin, well-known antioxidants: phenol (C6H5OH), resorcinol (C6H4(OH)(2)), pyrogallol (C6H3(OH)(3)), and mixtures of antioxidants with hemoglobin and albumin induced by Fenton reaction was studied. To calculate the kinetics of chemiluminescence processes, a scheme of reactions describing the process was worked out. On the basis of this scheme a system of differential equations was set up, where concentrations of the substances, participating in the process, were variables. The number of equations was equal to the quantity of the substances, participating in the reaction. Results. The light sum of the chemiluminescence induced by Fenton reaction monotonically decreases at concentrations of [H2O2]=10(-1) mol/L with the reduction of substrate concentration (with dilution). Dependence of S/S0 on the concentration of the fragments [RH] being oxidized, inhibitor [InH] and oxidized substance [ROOH] was calculated. There is no linear dependence between the light sum S/S0 and concentrations of [RH], [ROOH] and [InH] at [Fe2+]<[H2O2], therefore the results obtained were of a qualitative character. Conclusion. The chemiluminescence induced by Fenton reaction enables the investigators to observe the products of reaction rather than radicals. Fenton reaction runs in actually any substrate. The level of the chemiluminescence light sum, initiated by hydroxyl radicals - Fenton reaction - is determined by the rate constants of the initiating, continuing and chain breaking reaction. Increase or decrease of the chemiluminescence light sum speaks of various values of these constants, but does not show an antioxidant activity, i.e. inhibition of the chain reaction due to the formation of inactive products. Therefore, the ability of the substrate to be oxidized under the given conditions can be evaluated according to the level of the chemiluminescence induced by hydroxyl radicals generated in Fenton reaction.