title: In vitro antibacterial and antibiotic-potentiation activities of the methanol extracts from Beilschmiedia acuta, Clausena anisata, Newbouldia laevis and Polyscias fulva against multidrug-resistant Gram-negative bacteria.
abstract: BACKGROUND
  The present study was designed to investigate the antibacterial activities of the methanol extracts from different parts of Beilschmedia acuta Kosterm (Lauraceae), Clausena anisata (Willd) Hook (Rutaceae), Newbouldia laevis Seem (Bignoniaceae) and Polyscias fulva (Hiern) Harms (Araliaceae) as well as their synergistic effects with antibiotics against a panel of Gram-negative bacteria, including multi-drug resistant (MDR) phenotypes expressing active efflux pumps.
  
  
  METHODS
  Broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of the extracts, as well as those of antibiotics in association with the most active ones, B. acuta, N. laevis and P. fulva.
  
  
  RESULTS
  MIC values obtained indicate that extracts from the bark of B. acuta were active on all the 26 tested Gram-negative bacteria, with MICs ranging from values below 8 to 256 μg/mL. Other samples displayed selective activities, their inhibitory effects being observed on 9 (34.62 %) of the 26 bacterial strains for N. laevis leaves extract, 6 (23.10 %) for both C. anisata leaves and roots extracts, 7 (26.9 %) and 4 (15.4 %) for leaves and roots extracts of P. fulva respectively. Extract from B. actua bark displayed the best antibacterial activity with MIC values below 100 μg/mL against 16 (61.5 %) of the 26 tested microorganisms. The lowest MIC values (below 8 μg/mL) were obtained with this extract against Escherichia coli W3110 and Klebsiella pneumoniae ATCC11296. The MIC values of this extract were lower than those of ciprofloxacin against E. coli W3110, Enterobacter aerogenes ATCC13048, CM64 and Providencia stuartii NAE16. At MIC/2, the best percentages of synergistic effects (100 %), were obtained with B. acuta bark extract and tetracycline (TET) as well as with P. fulva leaves extract and TET and kanamycin (KAN).
  
  
  CONCLUSIONS
  The overall results of the present study provide information for the possible use of the studied plants and mostly Beilschmedia acuta in the control of bacterial infections including MDR phenotypes.
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon. presidentthankeo@yahoo.fr.
authors.forename: Simplice B
authors.initials: SB
authors.lastname: Tankeo
authors.affiliation: Laboratory of Natural Products Chemistry, Department of Chemistry, Faculty of Science, University of Dschang, Dschang, Cameroon. ptane@yahoo.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Tane
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon. kuetevictor@yahoo.fr.
authors.forename: Victor
authors.initials: V
authors.lastname: Kuete
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D027481:Araliaceae / Q000737:chemistry*; D029402:Bignoniaceae / Q000737:chemistry*; D002939:Ciprofloxacin / Q000494:pharmacology; D054700:Clausena / Q000737:chemistry*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D004357:Drug Synergism; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D007612:Kanamycin / Q000494:pharmacology; D019770:Lauraceae / Q000737:chemistry*; D000432:Methanol; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D027821:Rutaceae / Q000737:chemistry*; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D007612:Kanamycin; D002939:Ciprofloxacin; D013752:Tetracycline; D000432:Methanol