title: Antibacterial & antiplasmid activities of Helicteres isora L.
abstract: OBJECTIVE
  The multiple drug resistance (MDR) is a serious health problem and major challenge to the global drug discovery programmes. Most of the genetic determinants that confer resistance to antibiotics are located on R-plasmids in bacteria. The present investigation was undertaken to investigate the ability of organic extract of the fruits of Helicteres isora to cure R-plasmids from certain clinical isolates.
  
  
  METHODS
  Active fractions demonstrating antibacterial and antiplasmid activities were isolated from the acetone extracts of shade dried fruits of H. isora by bioassay guided fractionation. Minimal inhibitory concentration (MIC) of antibiotics and organic extracts was determined by agar dilution method. Plasmid curing activity of organic fractions was determined by evaluating the ability of bacterial colonies (pre treated with organic fraction for 18 h) to grow in the presence of antibiotics. The physical loss of plasmid DNA in the cured derivatives was further confirmed by agarose gel electrophoresis.
  
  
  RESULTS
  The active fraction did not inhibit the growth of either the clinical isolates or the strains harbouring reference plasmids even at a concentration of 400 microg/ml. However, the same fraction could cure plasmids from Enterococcus faecalis, Escherichia coli, Bacillus cereus and E. coli (RP4) at curing efficiencies of 14, 26, 22 and 2 per cent respectively. The active fraction mediated plasmid curing resulted in the subsequent loss of antibiotic resistance encoded in the plasmids as revealed by antibiotic resistance profile of cured strains. The physical loss of plasmid was also confirmed by agarose gel electrophoresis.
  
  
  CONCLUSIONS
  The active fraction of acetone extract of H. isora fruits cured R-plasmids from Gram-positive and Gram-negative clinical isolates as well as reference strains. Such plasmid loss reversed the multiple antibiotic resistance in cured derivatives making them sensitive to low concentrations of antibiotics. Acetone fractions of H. isora may be a source to develop antiplasmid agents of natural origin to contain the development and spread of plasmid borne multiple antibiotic resistance.
authors.affiliation: Department of Botany, University of Pune, Pune, India.
authors.forename: Varsha
authors.initials: V
authors.lastname: Shriram
authors.forename: Sheetal
authors.initials: S
authors.lastname: Jahagirdar
authors.forename: C
authors.initials: C
authors.lastname: Latha
authors.forename: Vinay
authors.initials: V
authors.lastname: Kumar
authors.forename: Prashant
authors.initials: P
authors.lastname: Dhakephalkar
authors.forename: Supada
authors.initials: S
authors.lastname: Rojatkar
authors.forename: Mahadeo G
authors.initials: MG
authors.lastname: Shitole
mesh_terms: D000096:Acetone; D001409:Bacillus cereus / Q000187:drug effects / Q000235:genetics*; D005591:Chemical Fractionation; D018432:Drug Resistance, Multiple / Q000235:genetics*; D004587:Electrophoresis, Agar Gel; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D005638:Fruit / Q000737:chemistry*; D007194:India; D019660:Malvaceae / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology*; D011815:R Factors / Q000187:drug effects / Q000235:genetics*
chemical_list: D010936:Plant Extracts; D000096:Acetone