title: Use of 1,4-naphthoquinones for control of Erwinia carotovora.
abstract: The antimicrobial effect of 5 naphthoquinones was tested against the phytopathogenic bacteria Erwinia carotovora. Disk diffusion tests and determination of minimal inhibitory concentrations (MIC) indicate that the compound naphthazarin (NTZ) has the best antibacterial activity among the naphthoquinones tested. Studies on the mode of action indicate the effect of NTZ was bactericidal at 10 microg/mL. When cultivation was done in the presence of sodium ascorbate, the restoration of E. carotovora growth was observed with 3 microg/mL NTZ, but not when a 10 microg/mL dose was used. The incubation of NTZ with bacterial suspension of E. carotovora resulted in important changes in the absorption spectra of this naphthoquinone, indicating that a redox reaction takes place. These results may suggest that NTZ induces an increase of reactive oxygen species that are toxic to the cell. The compound NTZ was also effective in preventing E. carotovora growth on potato tubers, inhibiting the soft rot development at a concentration of 2 mg/mL.
authors.affiliation: Laboratory of Applied Biochemistry and Microbiology, Department of Digestive Sciences, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil.
authors.forename: Luis F C
authors.initials: LF
authors.lastname: Medina
authors.forename: Valter
authors.initials: V
authors.lastname: Stefani
authors.forename: Adriano
authors.initials: A
authors.lastname: Brandelli
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods; D009285:Naphthoquinones / Q000494:pharmacology*; D016973:Pectobacterium carotovorum / Q000187:drug effects*; D010935:Plant Diseases / Q000382:microbiology*; D011198:Solanum tuberosum / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D009285:Naphthoquinones; C005503:naphthazarin; C035342:1,4-naphthoquinone