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Laboratory for Redox Regulation


Reactive oxygen species (ROS) is a nominal designation of hyper reactive substances that are derived from oxygen molecules through electron transfer. Singlet oxygen, superoxide anion, hydroxyl radical, and hydrogen peroxide are classified as ROS.

Usually, only negative aspects of ROS are discussed, such as its role in not only the development of "lifestyle diseases" but heavy metal-induced (such as arsenic) carcinogenesis. However, certain leukocytes attack pathogenic microorganisms by producing ROS, and it has been reported that certain antibiotics and anticancer agents show potential advantages by generating ROS to attack target microorganisms and cancer cells, so much more attention should be paid to beneficial aspects of ROS.

In our laboratory, we focus on research to develop and apply ways to analyse and regulate ROS, especially free radicals that contain unpaired electrons. With respect to dentistry, we also apply our research to the removal of pathogenic organisms from the oral cavity by producing oxygen radicals through light irradiation of the disinfectant oxyfluorfen.

Because of an extremely short half-life of these free radicals, radical stabilization technology such as a spin-trapping technique and optical analysis equipment such as an electron spin resonance (ESR) spectrometer are essential to analyze them. While the short half-life of the radicals makes it difficult to analyze and control them, it also makes it possible to be free from residual toxicity, tempting us to expect further applications of the radicals.

Faculty configuration

  • Yoshimi NiwanoProf.Yoshimi Niwano

Topics of Research

  • Radical Generation Mechanisms of Photolysis of Hydrogen Peroxide and Sonolysis of Water
  • Elucidation of the Bactericidal Mechanism of Radicals
  • Application of Radicals to Sterilization Technology
  • In Vivo Control Mechanism of Redox Reactions
  • Development of Measurement Technology for Reactive Oxygen Radicals Generated In Vivo

Recent Performance

  1. Harada A, Nakamura K, Kanno T, Inagaki R, Örtengren U, Niwano Y, Sasaki K, Egusa H. Fracture resistance of CAD/CAM-generated composite resin-based molar crowns. Eur J Oral Sci, (in press).
  2. Nakamura K, Ishiyama K, Sheng H, Ikai H, Kanno T, Niwano Y. Bactericidal activity and mechanism of photo-irradiated polyphenols against Gram-positive and -negative bacteria. J Agric Food Chem, (in press).
  3. Mokudai T, Kanno T, Niwano Y. Postantifungal-like effect of sublethal treatment of Candida albicans with acid-electrolyzed water. Arc Oral Biol, 60(3):479-487, 2015.
  4. Toki T, Nakamura K, Kurauchi M, Kanno T, Katsuda Y, Ikai H, Hayashi E, Egusa H, Sasaki K, Niwano Y. Synergistic interaction between wavelength of light and concentration of H2O2 in bactericidal activity of photolysis of H2O2. J Biosci Bioeng, 119(3):358-362, 2015.
  5. Kurauchi M, Niwano Y, Shirato M, Kanno T, Nakamura K, Egusa H, Sasaki K. Cytoprotective effect of short-term pretreatment with proanthocyanidin on human gingival fibroblasts exposed to harsh environmental conditions. PLoS ONE, 9(11):e113403, 2014.
  6. Tada M, Kohno M, Niwano Y. Alleviation effect of arbutin on oxidative stress generated through tyrosinase reaction with L-tyrosine and L-DOPA. BMC Biochem, 15:23, 2014.
  7. Tsuruya M, Niwano Y, Nakamura K, Kanno T, Egusa H, Sasaki K. Acceleration of proliferative response of mouse fibroblasts by short-time pretreatment with polyphenols. Appl Biochem Biotechnol, 174(6):2223-2235, 2014.
  8. Niwano Y, Kanno T, Iwasawa A, Ayaki M, Tsubota K. Blue light injures corneal epithelial cells in the mitotic phase in vitro. Br J Ophthalmol, 98(7):990-992, 2014.

Laboratory Contacts

E-mail:niwano*m.tohoku.ac.jp (Please change * to @.)