title: Antioxidant activities of nano-bubble hydrogen-dissolved water assessed by ESR and 2,2'-bipyridyl methods.
abstract: We prepared nano-bubble hydrogen-dissolved water (nano-H water) which contained hydrogen nano-bubbles of <717-nm diameter for 54% of total bubbles. In the DMPO-spin trap electron spin resonance (ESR) method, the DMPO-OH:MnO ratio, being attributed to amounts of hydroxyl radicals (OH), was 2.78 for pure water (dissolved hydrogen [DH]≤0.01 ppm, oxidation-reduction potential [ORP]=+324 mV), 2.73 for tap water (0.01 ppm, +286 mV), 2.93 for commercially available hydrogen water (0.075 ppm, +49 mV), and 2.66 for manufactured hydrogen water (0.788 ppm, -614 mV), whereas the nano-H water (0.678 ppm, -644 mV) exhibited 2.05, showing the superiority of nano-H water to other types of hydrogen water in terms of OH-scavenging activity. Then, the reduction activity of nano-H water was assessed spectrophotometrically by the 2,2'-bipyridyl method. Differential absorbance at 530 nm was in the order: 0.018 for pure water, 0.055 for tap water, 0.079 for nano-H water, 0.085 for commercially available hydrogen water, and 0.090 for manufactured hydrogen water, indicating a prominent reduction activity of hydrogen water and nano-H water against oxidation in ascorbate-coupled ferric ion-bipyridyl reaction. Thus, nano-H water has an improved antioxidant activity as compared to hydrogen water of similar DH-level, indicating the more marked importance of nano-bubbles rather than the concentration of hydrogen in terms of OH-scavenging.
authors.affiliation: Laboratory of Cell-Death Control BioTechnology, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Nanatsuka 562, Shobara, Hiroshima 727-0023, Japan; Radio Isotope Facilities for Medical Science, Life Science Research Center, Mie University, Edobashi 2-174, Tsu, Mie 514-8507, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kato
authors.affiliation: -600mV Co., Ltd. Matsuhama-cho 2-4-1, Fukuyama, Hiroshima 720-0802, Japan.
authors.forename: Daigo
authors.initials: D
authors.lastname: Matsuoka
authors.affiliation: Laboratory of Cell-Death Control BioTechnology, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Nanatsuka 562, Shobara, Hiroshima 727-0023, Japan; Department of Radiological Technology, Faculty of Health Sciences, Butsuryo College of Osaka, Otorikitamachi 3-33, Nishi-ku, Sakai, Osaka 593-8328, Japan. Electronic address: miwa@butsuryo.ac.jp.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Miwa
mesh_terms: D015082:2,2'-Dipyridyl / Q000032:analysis / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006859:Hydrogen / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D010084:Oxidation-Reduction; D014867:Water / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D014867:Water; D015082:2,2'-Dipyridyl; D006859:Hydrogen
keywords: 2,2′-Bipyridyl method; Antioxidant; Electron spin resonance; Hydrogen water