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 3

Effect of pH on the reduction of ^⋅cPTIO in the presence of SeO₃²⁻ induced by H₂S. Time resolved UV-VIS spectra of the interaction of H₂S (100 μmol L⁻¹ final) with ^⋅cPTIO/SeO₃²⁻ (100/50 in μmol L⁻¹ final) at pH 6.5 (a), 7.0 (b), 7.4 (c), 8.0 (d), and 9.0 (e). The first spectrum was recorded 15 s after H₂S addition (solid red line) followed each 30 s by: long dash red, medium dash red, short dash red, dotted red, solid blue line, long dash blue, medium dash blue, etc. Samples were measured every 30 s for 20 min. The black line represents the spectrum of ^⋅cPTIO/SeO₃²⁻ before the H₂S addition. (f) Dependence of ^⋅cPTIO (100 μmol L⁻¹) reduction by H₂S/SeO₃²⁻ (100/50 in μmol L⁻¹) on pH. Data were taken from the spectra shown in (a), (b), (c), (d), and (e) as a minimum of A₅₆₀ in the range of 0-4 min. The buffers consisted of 100 mmol L⁻¹ sodium phosphate, 100 μM DTPA, 37°C, and pH values were adjusted to desired pH.