Aims: To investigate the utility of ozone nanobubble water (NBW3) for the treatment of Helicobacter pylori in the stomach, we tested the influence of pepsin concentrations and pH levels on the disinfective activity of NBW3, and the cytotoxicity of NBW3 against mammalian cells and mucosa. Methods: Different concentrations of pepsin were dissolved in NBW3, and the bactericidal activity was tested on H. pylori. NBW3 was adjusted to different pH levels (2.0-7.4) and the bactericidal activity on H. pylori was also tested. To examine the cytotoxicity of NBW3, AGS cells, human gastric epithelial cells, were treated with NBW3 and the viability of the cells was evaluated in vitro. Furthermore, NBW3 was administered to mice and gastric mucosal damage was evaluated by histology. Results: Pepsin reduced the disinfective activity of NBW3 on H. pylori in a pepsin concentration-dependent manner. NBW3 showed stable disinfective activity at all pH levels examined.Cytotoxicity of NBW3 against human gastric epithelial cells and gastric mucosa was not observed in our experimental setting. Conclusions: NBW3 can sustain its disinfective activity in wide range of pH levels and show no cytotoxicity on mammalian cells and tissue. Pepsin can inhibit NBW3 activity in a dose-dependent manner.

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