Enhanced Removal of Free Radicals by Aqueous Hydrogen Nanobubbles and Their Role in Oxidative Stress

Elevated levels of reactive oxygen radicals caused by environmental stress are the key triggers of inflammation, aging, and disease; thus, it is critical to develop novel reactive oxygen radical scavenging methods with high efficiency and low toxicity. As a result of their selective reactive oxygen radical removal, hydrogen molecules are strong candidates, but their application is limited by the small hydrogen supply and short duration of action. In this study, we for the first time combined nanobubble (NB) technology and hydrogen water to remove reactive oxygen species (ROS) using copper ions as a representative environmental pollutant and Tetrahymena thermophila as a model organism. Hydrogen NBs displayed a remarkable capability of removing H2O2 and O2•– at molar ratios of 8:1 and 240:1, respectively, which were unable to be removed by dissolved hydrogen molecules only. During the oxidative defense phase, hydrogen NB water either directly removed ROS or increased the activity and relative expression of glutathione peroxidase (GSH-Px). During the oxidative inhibition phase, hydrogen NB water exerted antioxidant effects mainly by increasing the activities of superoxide dismutase and GSH-Px as well as the expression of the corresponding genes. Our results provide an important theoretical support for the wide application of hydrogen NBs in empowering the antioxidant defense system.