title: Antibacterial, antibiofilm and cytotoxic activities of Terminalia fagifolia Mart. extract and fractions.
abstract: BACKGROUND
  The methicillin resistance of bacteria from the genus Staphylococcus and its ability to form biofilms are important factors in pathogenesis of these microorganisms. Thus, the search for new antimicrobials agents, especially from plants, has been intensified. In this context, Terminalia species have been the subject of research for many pharmacological activities. In this study we evaluated the antibacterial, antibiofilm and cytotoxic activities of the ethanol extract (EtE) from Terminalia fagifolia stem bark as well as that of three fractions of the extract (AqF, HaF and WSF).
  
  
  METHODS
  We determined the minimum inhibitory concentration (MIC) by microdilution in 96-well plates, where the strains were exposed to serial dilutions of the ethanol extract and fractions, ranging from 12.5 to 400 μg/mL. We then determined the minimum bactericidal concentration (MBC), seeding the inoculum (10 μL) with concentrations equal to or greater than the MIC in Mueller-Hinton agar. To test the antibiofilm activity biofilm formation was induced in the presence of concentrations equivalent to 1/2, 1/4 and 1/8 of the MIC extract or fraction tested. In addition, the effect of the EtE and the fractions on cell viability was tested by the MTT assay on human MCF-7 breast cancer and mouse fibroblast NIH/3T3. To obtain high-resolution images of the effect of the aqueous fraction on the bacterial morphology, atomic force microscopy (AFM) imaging of treated S. aureus cells was performed.
  
  
  RESULTS
  We observed antibacterial activity of EtE and fractions with MICs ranging from 25-200 μg/mL and MBCs ranging from 200-400 μg/mL. Regarding antibiofilm activity, both the EtE as the AqF, HaF and WSF fractions showed significant inhibition of the biofilm formation, with inhibition of biofilms formation of over 80% for some strains. The EtE and fractions showed a moderate cytotoxicity in cell line NIH/3T3 viability and potential antitumoral activity on human breast cancer cell line MCF-7. The microscopic images obtained revealed morphological changes to the S. aureus ATCC 29213 surface caused by AqF, as well as significant size alterations.
  
  
  CONCLUSIONS
  The results show potential antibacterial, antibiofilm and antitumoral activities of the ethanol extract and fractions of T. fagifolia.
authors.affiliation: Center for Research on Medicinal Plants, Federal University of Piauí, Piauí, Brazil. alyne_biomed@hotmail.com.|Biodiversity and Biotechnology Research Center, Biotec, Federal University of Piauí, Parnaíba, Piauí, Brazil. alyne_biomed@hotmail.com.
authors.forename: Alyne Rodrigues
authors.initials: AR
authors.lastname: de Araujo
authors.affiliation: Biodiversity and Biotechnology Research Center, Biotec, Federal University of Piauí, Parnaíba, Piauí, Brazil. pquelemes@gmail.com.
authors.forename: Patrick Veras
authors.initials: PV
authors.lastname: Quelemes
authors.affiliation: Biodiversity and Biotechnology Research Center, Biotec, Federal University of Piauí, Parnaíba, Piauí, Brazil. marciaperfeito26@gmail.com.
authors.forename: Márcia Luana Gomes
authors.initials: ML
authors.lastname: Perfeito
authors.affiliation: Biodiversity and Biotechnology Research Center, Biotec, Federal University of Piauí, Parnaíba, Piauí, Brazil. luizaianny@gmail.com.|Campus Ceilândia, University of Brasília, Brasília, Brazil. luizaianny@gmail.com.
authors.forename: Luíza Ianny
authors.initials: LI
authors.lastname: de Lima
authors.affiliation: Federal University of Rio Grande do Norte, Rio Grande do Norte, Brazil. melkasa@yahoo.com.br.
authors.forename: Melka Coêlho
authors.initials: MC
authors.lastname: Sá
authors.affiliation: Department of Physiology and Biophysics, Federal University of Piauí, Piauí, Brazil. phumbertonunes@yahoo.com.br.
authors.forename: Paulo Humberto Moreira
authors.initials: PH
authors.lastname: Nunes
authors.affiliation: Campus Ceilândia, University of Brasília, Brasília, Brazil. bygra1@gmail.com.
authors.forename: Graziella Anselmo
authors.initials: GA
authors.lastname: Joanitti
authors.affiliation: UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal. peter.eaton@fc.up.pt.
authors.forename: Peter
authors.initials: P
authors.lastname: Eaton
authors.affiliation: Department of Veterinary Morphology and Physiology, Federal University of Piauí, Piauí, Brazil. mrsapijf@gmail.com.
authors.forename: Maria José Dos Santos
authors.initials: MJ
authors.lastname: Soares
authors.affiliation: Center for Research on Medicinal Plants, Federal University of Piauí, Piauí, Brazil. jrsaleite@gmail.com.|Biodiversity and Biotechnology Research Center, Biotec, Federal University of Piauí, Parnaíba, Piauí, Brazil. jrsaleite@gmail.com.
authors.forename: José Roberto
authors.initials: JR
authors.lastname: de Souza de Almeida Leite
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D051379:Mice; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D029766:Terminalia / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts