Free radical–scavenging activity of sulfurous water investigated by electron paramagnetic resonance (EPR) spectroscopy

ABSTRACTThe aim of the study was to explore the antiradical activity of sulfurous water, used for inhalatory therapy (characterized by the presence of sulfhydryl [HS]) by means of electron paramagnetic resonance (EPR) spectroscopy. The effects of sulfurous water corresponding to the concentrations from 16 down to 0.25 μg/mL of HS were tested by means of Fenton reaction (HO•), KO2–crown ether system (O2−•), and EPR of Tempol and of Fremy's salt radical. All of these assays were made using natural sulfurous water or degassed sulfurous water (no detectable HS) or reconstituted sulfurous water (degassed plus NaHS). The free radicals were significantly inhibited by natural water with HS concentrations ranging from 16 to 1 μg/mL for HO•, Tempol, and Fremy's salt, and O2−• was significantly inhibited from 16 and 2 μg/mL. The tests of degassed water did not reveal any significant differences from baseline values. The tests of reconstituted water led to significant results overlapping those obtained using natural ...