title: Isolation of antibacterial compounds from Quercus dilatata L. through bioassay guided fractionation.
abstract: BACKGROUND
  Four medicinal plants (Chrozophora hierosolymitana Spreng, Chrysanthemum leucanthemum L., Ephedra gerardiana Wall. ex Stapf, and Quercus dilatata L.) used by indigenous healers to treat various infectious diseases were selected for the present study. The major objective of the present study was isolation and characterization of antimicrobial components from the crude plant extracts using bioassay guided fractionation.
  
  
  METHODS
  Seven methanolic extracts of the four plants were screened to identify any antimicrobial agents present in them. The active crude plant extract was fractionated first by solvent partitioning and then by HPLC. Characterization of the active fractions was done by using spectrophotometer.
  
  
  RESULTS
  All the seven methanolic extracts showed low antifungal activity, however, when these extracts were tested for antibacterial activity, significant activity was exhibited by two extracts. The extract of aerial parts of Q. dilatata was most active and therefore, was selected for further analysis. Initially fractionation was done by solvent-solvent partitioning and out of six partitioned fractions, ethanol fraction was selected on the basis of results of antibacterial activity and phytochemical analysis. Further, fractionation was carried out by RP-HPLC and purified active subfractions were characterized by comparing their absorption spectra with that of the known natural products isolated from the plants of Quercus genus.
  
  
  CONCLUSIONS
  The results suggest that this is the first report of the isolated antibacterial compounds from this genus.
authors.affiliation: Department of Biochemistry, Quaid i Azam University, Islamabad, Pakistan.
authors.forename: Maryam
authors.initials: M
authors.lastname: Jamil
authors.forename: Ihsan
authors.initials: I
authors.lastname: ul Haq
authors.forename: Bushra
authors.initials: B
authors.lastname: Mirza
authors.forename: Mazhar
authors.initials: M
authors.lastname: Qayyum
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001681:Biological Assay; D005591:Chemical Fractionation; D031202:Chrysanthemum / Q000737:chemistry; D052978:Disk Diffusion Antimicrobial Tests; D029789:Ephedra / Q000737:chemistry; D000431:Ethanol; D019665:Euphorbiaceae / Q000737:chemistry; D005260:Female; D005658:Fungi / Q000187:drug effects* / Q000254:growth & development; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000254:growth & development; D008297:Male; D051379:Mice; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D029963:Quercus / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D010936:Plant Extracts; D000431:Ethanol