title: Antimicrobial and antioxidant properties of methanol extract, fractions and compounds from the stem bark of Entada abyssinica Stend ex A. Satabie.
abstract: BACKGROUND
  The aim of this study was to evaluate the antimicrobial and antioxidant activities of the methanol extract, fractions and isolated compounds from Entada abyssinica stem bark, plant used traditionally against gastrointestinal infections.
  
  
  METHODS
  The methanol extract of E. abyssinica stem bark was pre-dissolved in a mixture of methanol and water, and then partitioned between n-hexane, ethyl acetate and n-butanol. The ethyl acetate portion was fractionated by column chromatography and the structures of isolated compounds elucidated by analysis of spectroscopic data and comparison with literature data. Antimicrobial activity was assayed by broth microdilution techniques on bacteria and yeasts. The antioxidant activity was determined by DPPH radical scavenging method.
  
  
  RESULTS
  Four known compounds [(5S,6R,8aR)-5-(carboxymethyl)-3,4,4a,5,6,7,8,8a-octahydro-5,6,8a-trimethylnaphthalenecarboxylic acid (1), methyl 3,4,5-trihydroxybenzoate (2), benzene-1,2,3-triol (3) and 2,3-dihydroxypropyltriacontanoate (4)] were isolated. Compared to the methanol extract, fractionation increased the antibacterial activities of the n-hexane and ethyl acetate fractions, while the antifungal activities increased in ethyl acetate, n-butanol and aqueous residue fractions. The isolated compounds were generally more active on bacteria (9.7 to 156.2 μg/ml) than yeasts (78.1 to 312.5 μg/ml). Apart from compound 1, the three others displayed DPPH· scavenging activity (RSa), with RSa50 values of 1.45 and 1.60 μg/ml.
  
  
  CONCLUSIONS
  The results obtained from this study support the ethnomedicinal use of E. abyssinica in the treatment of gastrointestinal infections and the isolated compounds could be useful in the standardisation of antimicrobial phytomedicine from this plant.
authors.affiliation: Laboratory of Microbiology and Antimicrobial Substances, Faculty of Science, University of Dschang, Cameroon.
authors.forename: Gerald N
authors.initials: GN
authors.lastname: Teke
authors.forename: Paul K
authors.initials: PK
authors.lastname: Lunga
authors.forename: Hippolyte K
authors.initials: HK
authors.lastname: Wabo
authors.forename: Jules-Roger
authors.initials: JR
authors.lastname: Kuiate
authors.forename: Gerard
authors.initials: G
authors.lastname: Vilarem
authors.forename: Geraldine
authors.initials: G
authors.lastname: Giacinti
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Oshima
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000378:metabolism; D007887:Fabaceae / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D010851:Picrates / Q000378:metabolism; D024301:Plant Bark; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018547:Plant Stems; D015003:Yeasts / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D000975:Antioxidants; D001713:Biphenyl Compounds; D010851:Picrates; D010936:Plant Extracts; C004931:1,1-diphenyl-2-picrylhydrazyl