A comparison of chemical systems for luminometric determination of antioxidant capacity towards individual reactive oxygen species.

The aim of the study was to investigate the reactive oxygen species (ROS) production in the hypoxanthine-xanthinoxidase (HX-XO), hydrogen peroxide-ferrous sulphate (H2O2-FeSO4) and hydrogen peroxide (H2O2) systems by using various concentrations of ROS scavengers, such as superoxide dismutase (SOD), dimethylthiourea (DMTU) or catalase (CAT). Luminol (0.8 mmol/L) was dissolved in a borate buffer, pH 9.0, and was used as a luminophor in the chemiluminescence (CL) measurements. In the HX-XO system SOD, CAT and DMTU deepened the CL signal, whereas in the H2O2-FeSO4 system, only CAT and DMTU deepened the CL signal, and in the H2O2 system SOD and CAT increased and DMTU deepened the CL signal. Electron spin resonance (ESR) measurements were performed only in the H2O2-FeSO4 system. 5,5-dimethyl-pyrroline-N-oxide (DMPO) was used as a spin trap. According to typical ESR spectra, .OH was produced in this chemical system. It can be concluded that the chemical systems do not produce single reactive oxygen species but a mixture of them.