title: Aminonaphthoquinone induces oxidative stress in Staphylococcus aureus.
abstract: The biological activity of 5-amino-8-hydroxy-1,4-naphthoquinone (ANQ) on Staphylococcus aureus was investigated in comparison with the unsubstituted 1,4-naphthoquinone (NQ). Complete inhibition of microbial growth was observed with ANQ and NQ at 50 and 10 microg/mL, respectively. The antibacterial effect of naphthoquinones decreased in the presence of sodium ascorbate, but the superoxide scavenger 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron) was able to protect S. aureus only from the harmful effect of ANQ. Naphthoquinones blocked oxygen uptake and induced cyanide-insensitive oxygen consumption. When combining rotenone or salicylhydroxamic acid with ANQ or NQ, a slight decrease in respiratory activity was observed. Assays in the presence of naphthoquinones induced an increase of lipid peroxidation in S. aureus, as determined by thiobarbituric acid reactive substances. These results showed that 1,4-naphthoquinones effectively act as electron acceptors and induce an increase in reactive oxygen species that are toxic to S. aureus cells.
authors.affiliation: Laboratório de Bioquímica e Microbiologia Aplicada, Departamento de Ciência de Alimentos, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brasil.
authors.forename: L F C
authors.initials: LF
authors.lastname: Medina
authors.forename: P F
authors.initials: PF
authors.lastname: Hertz
authors.forename: V
authors.initials: V
authors.lastname: Stefani
authors.forename: J A P
authors.initials: JA
authors.lastname: Henriques
authors.forename: A
authors.initials: A
authors.lastname: Zanotto-Filho
authors.forename: A
authors.initials: A
authors.lastname: Brandelli
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D009285:Naphthoquinones / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development
chemical_list: C518633:5-amino-8-hydroxy-1,4-naphthoquinone; D000900:Anti-Bacterial Agents; D009285:Naphthoquinones; D017382:Reactive Oxygen Species; C035342:1,4-naphthoquinone