title: Molecular hydrogen attenuates radiation-induced nucleobase damage to DNA in aerated aqueous solutions.
abstract: The main aim of the present study is to gain mechanistic insights into the modulating effect of molecular hydrogen on the γ-radiation-induced alteration pathways of DNA nucleobases.
  
  
  
  Aerated aqueous solutions of calf thymus DNA were exposed to a (60)Co source at doses ranging from 0 to 55 Gy under normoxic conditions, in the presence or not of 0.7 MPa hydrogen or helium. The measurement of several modified bases was performed using HPLC associated with electrospray ionization tandem pass spectrometry (HPLC-ESI-MS/MS). Bleaching of aqueous solutions of p-nitrosodimethylaniline (p-NDA) solutions was also used to allow the quantification of hydroxyl radical (•OH) formation.
  
  
  
  pNDA bleaching was significantly reduced in the presence of hyperbaric hydrogen. This is undoubtedly due to (•)OH scavenging by H2 since, under the same conditions, He had no effect. Similarly, base alterations were significantly reduced in the presence of hydrogen, as compared to controls under normal atmosphere or in the presence of helium. The relative proportions of modified nucleobases were not changed, showing that the only effect of H2 is to scavenge (•)OH without exhibiting reducing properties.
  
  
  
  Our findings demonstrate that H2 exerts a significant protection against radiation-induced DNA base damage in aqueous solutions, (•)OH scavenging being the only mechanism involved.
authors.affiliation: a CNRS, NICN UMR 7259, Aix Marseille University , Marseille , France ;
authors.forename: Mhamad
authors.initials: M
authors.lastname: Abou-Hamdan
authors.affiliation: b COMEX SA , Marseille , France ;
authors.forename: Bernard
authors.initials: B
authors.lastname: Gardette
authors.affiliation: c Département de Médecine Nucléaire et de Radiobiologie , Université de Sherbrooke , Sherbrooke , Québec J1H 5N4 , Canada ;
authors.forename: Jean
authors.initials: J
authors.lastname: Cadet
authors.affiliation: a CNRS, NICN UMR 7259, Aix Marseille University , Marseille , France ;
authors.forename: Bouchra
authors.initials: B
authors.lastname: Gharib
authors.affiliation: a CNRS, NICN UMR 7259, Aix Marseille University , Marseille , France ;
authors.forename: Max
authors.initials: M
authors.lastname: De Reggi
authors.affiliation: d INAC, LCIB, LAN, Univ. Grenoble Alpes , Grenoble , France ;
authors.forename: Thierry
authors.initials: T
authors.lastname: Douki
authors.affiliation: e CEA Cadarache , St Paul Lez Durance Cedex , France.
authors.forename: Christian
authors.initials: C
authors.lastname: Triantaphylides
mesh_terms: D000388:Air; D004247:DNA / Q000235:genetics / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006859:Hydrogen / Q000737:chemistry*; D009711:Nucleotides / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects; D011829:Radiation Dosage; D012996:Solutions; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry*
chemical_list: D009711:Nucleotides; D012996:Solutions; D014867:Water; D006859:Hydrogen; D004247:DNA; C427203:calf thymus DNA
keywords: DNA base oxidation; hydroxyl radical scavenging; molecular hydrogen-mediated protection; oxidized 2′-deoxyribonucleosides