Anti-inflammatory and antitumor action of hydrogen via reactive oxygen species.

Hydrogen (H2) has advantages that lead it to be used as a novel antioxidant in preventive and therapeutic applications. H2 can permeate into biomembranes, cytosol, mitochondria and nuclei, and can be dissolved in water or saline to produce H2 water or H2-rich saline. H2 selectively reduces oxidants of the detrimental reactive oxygen species (ROS), including hydroxyl radicals (·OH) and peroxynitrite (ONOO-), which serve a causative role in the promotion of tumor cell proliferation, invasion and metastasis, but do not disturb metabolic oxidation-reduction reactions in cell signaling. Compared with traditional antioxidants, H2 is a small molecule that can easily dissipate throughout the body and cells; thus, it may be a safe and effective antioxidant for inflammatory diseases and cancer, since ROS usually initiates tumor progression. Treatment with H2 may involve correction of the oxidative/anti-oxidative imbalance and suppression of inflammatory mediators. Therefore the present review will discuss the anti-inflammatory and anti-tumorigenic action of H2 via ROS.