title: An unusual reduction on the quinonoid ring of 5-amino-8-hydroxy-1,4-naphthoquinone by Staphylococcus aureus.
abstract: OBJECTIVE
  The objective of this study was to investigate the interactions between 5-amino-8-hydroxy-1,4-naphthoquinone (ANQ) and Staphylococcus aureus.
  
  
  RESULTS
  The compound ANQ display antimicrobial activity against S. aureus. During incubation with 50 microg ml(-1) of ANQ, an unusual reduction reaction takes place and leads to the isolation of 2,3-dihydro-5-amino-8-hydroxy-1,4-naphthoquinone (ANQ-H(2)), fully characterized by means of (13)C-NMR and (1)H-NMR, plus infrared, UV-visible and mass spectroscopy. Oxygen uptake by S. aureus cells was inhibited by ANQ, but in a significantly minor extent by ANQ-H(2).
  
  
  CONCLUSIONS
  The ability of S. aureus to reduce the double bond at C2-C3 of the ANQ is a unusual behaviour for biological transformation of naphthoquinones.
  
  
  CONCLUSIONS
  This uncommon reaction may provide valuable understanding of the S. aureus regarding to the antimicrobial effect and the acquisition of resistance to naphthoquinones.
authors.affiliation: Laboratório de Bioquímica e Microbiologia Aplicada, Departamento de Ciências dos Alimentos, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: L F C
authors.initials: LF
authors.lastname: Medina
authors.forename: V
authors.initials: V
authors.lastname: Stefani
authors.forename: A
authors.initials: A
authors.lastname: Brandelli
mesh_terms: D009285:Naphthoquinones / Q000378:metabolism*; D010084:Oxidation-Reduction; D013211:Staphylococcus aureus / Q000378:metabolism*
chemical_list: D009285:Naphthoquinones