Products of Sulfide/Selenite Interaction Possess Antioxidant Properties, Scavenge Superoxide-Derived Radicals, React with DNA, and Modulate Blood Pressure and Tension of Isolated Thoracic Aorta

Figure 5

EPR spectra of ^⋅BMPO in the presence of O₂^⋅− are modulated by H₂S/SeO₃²⁻. Representative EPR spectra of the ^⋅BMPO adducts were monitored in 10% saturated KO₂/DMSO solution in 50 mmol L⁻¹ sodium phosphate buffer, 0.1 mmol L⁻¹ DTPA, pH 7.4, 37°C in the presence of the various investigated chalcogen species and 20 mmol L⁻¹ BMPO. Sets of individual EPR spectra of the ^⋅BMPO adducts monitored upon 15 sequential scans, each 42 s (a1-h1), starting acquisition 2 min after sample preparation in: control 10% KO₂/DMSO in the buffer (a1), the KO₂/DMSO in the presence of 25 μmol L⁻¹ SeO₃²⁻ (b1), 25 μmol L⁻¹ H₂S (c1), mixture of 25/25 in μmol L⁻¹ H₂S/SeO₃²⁻ (d1), 25/25 in μmol L⁻¹ H₂S/SeO₃²⁻ preincubated 5 min before KO₂/DMSO stock solution addition (e1), 50 μmol L⁻¹ H₂S (f1), mixture of 50/25 in μmol L⁻¹ H₂S/SeO₃²⁻ (g1), and 50/25 in μmol L⁻¹ H₂S/SeO₃²⁻ preincubated 5 min before addition of KO₂/DMSO stock solution (h1). The spectra (a2-h2) show details of the accumulated first ten spectra of the (a1-h1) sets. The intensities of the time-dependent EPR spectra (a1-h1) and detailed spectra (a2-h2) are comparable; they were measured under identical EPR settings. EPR modulation amplitude 0.15 mT. (a3-h3) Comparison of the integral intensity of individual components of simulated BMPO+O₂^⋅− without (control) and with chalcogen species shown in (a1-h1). The first five EPR spectra were accumulated and used for simulation. The data represent the means of ; standard error was ≤10% of the mean value. Simulated relative intensities of the two conformers of the radicals: ^⋅BMPO-OOH1 (black), ^⋅BMPO-OOH2 (red), ^⋅BMPO-OH1 (green), ^⋅BMPO-OH2 (yellow), and ^⋅BMPO-C (blue).