title: Stannous chloride mediates single strand breaks in plasmid DNA through reactive oxygen species formation.
abstract: Stannous ion (Sn) has been employed in nuclear medicine and in food industry. We described that Stannous Chloride (SnCl2) inactivation effect in Escherichia coli is mediated by a Fenton-like reaction. The effect of SnCl2 was studied through: (i) the alteration of plasmid topology in neutral and acidic pH by gel electrophoresis; and (ii) the transformation efficiency of an wild type E. coli strain. Treatment of plasmid DNA pUC 9.1 with SnCl2, at pH 7.4, results in DNA single-strand breaks (SSB), in a dose-dependent manner. Addition of sodium benzoate partly inhibited the DNA damage, while EDTA completely abolishes DNA-SSB. Furthermore, the ability of the plasmid to transform E. coli was reduced. At pH 1.3, SnCl2 exerts a protective effect on plasmid against HCI depurination. Our results suggest the generation of ROS, such as *OH by a Fenton-like reaction, close to the site of the lesions due to a possible complexation of stannous ion to DNA.
authors.affiliation: Departamento de Biofisica e Biometria, Instituto de Biologia Roberto Alcântara Gomes, UERJ, Rio de Janeiro, Brazil.
authors.forename: F J
authors.initials: FJ
authors.lastname: Dantas
authors.forename: M O
authors.initials: MO
authors.lastname: Moraes
authors.forename: J C
authors.initials: JC
authors.lastname: de Mattos
authors.forename: R J
authors.initials: RJ
authors.lastname: Bezerra
authors.forename: E F
authors.initials: EF
authors.lastname: Carvalho
authors.forename: M B
authors.initials: MB
authors.lastname: Filho
authors.forename: A
authors.initials: A
authors.lastname: Caldeira de Araújo
mesh_terms: D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D010957:Plasmids; D017382:Reactive Oxygen Species; D017971:Tin Compounds / Q000633:toxicity*
chemical_list: D004277:DNA, Single-Stranded; D017382:Reactive Oxygen Species; D017971:Tin Compounds; C023599:stannous chloride