title: Probable mechanisms of biocidal action of Cocos nucifera Husk extract and fractions on bacteria isolates.
abstract: BACKGROUND
  The incidence of resistance to the existing antibiotics by microorganisms demand increased effort in the development of new antibiotics for the treatment of microbial infections and diseases. Infections due to multidrug resistant pathogens are difficult to manage due to relatively limited choices of antimicrobial agents. This study investigated antimicrobial activities of the husk extract of Cocos nucifera on some bacteria that are associated with human diseases.
  
  
  METHODS
  Powdered husk of Cocos nucifera was cold extracted using mixture of methanol and distilled water in ration 3:2 (v/v). Extract was partitioned into n-hexane. Chloroform, ethylacetate and n-butanol fractions and thereafter, the minimum inhibitory concentrations (MICs) of the extract and those of the fractions were determined. The ethylacetate fraction was found to be more active and was partially purified by a combination of thin-layer and column chromatography. Finally, the rate of killing, leakages of proteins, potassium ions and nucleotides from the tests bacterial cells were determined.
  
  
  RESULTS
  The minimum Inhibitory concentrations (MICs) of the extract ranged between 0.39 and 12.50 mg/ml and those of the fractions ranged between 0.16 and 5.00 mg/ml. The time-kill assay revealed a minimum of 27.8% killed at 1 × MIC after 15 min contact time with the fractions and a minimum of 95% killed after 120 min. Varying amount of proteins, potassium ions as well as nucleotides were leaked from selected bacterial isolates by the four active fractions. The amount of proteins leaked from the cells after 15 min contact time ranged between 3.56 and 19.08 μg/ml at 1 × MIC and between 10.97 and 19.54 μg/ml at 2 × MIC. The amount of potassium ions leaked from the cells after 15 min contact time ranged between 0.182 and 0.379 mg/ml at 1 × MIC and between 0.227 and 0.561 mg/ml at 2 × MIC. The nucleotides leaked from the cells after 15 min contact time ranged between 0.609 and 2.446 μg/ml at 1 × MIC and between 0.897 and 2.841 μg/ml at 2 × MIC.
  
  
  CONCLUSIONS
  This study established the possibility of developing antimicrobial agents of natural origin to combat resistance to antimicrobial compounds by some pathogens currently being experienced in agricultural and health care environments.
authors.affiliation: Department of Microbiology, Obafemi Awolowo University, Ile Ife, Osun State, Nigeria. dakinpelu@yahoo.com.|Applied and Environmental Microbiology Research Group (AEMREG), Department of Microbiology and Biochemistry, University of Fort Hare, Alice, 5700, South Africa. dakinpelu@yahoo.com.|SA-MRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, 5700, South Africa. dakinpelu@yahoo.com.
authors.forename: David A
authors.initials: DA
authors.lastname: Akinpelu
authors.affiliation: Department of Microbiology, Obafemi Awolowo University, Ile Ife, Osun State, Nigeria. jkadekunle@yahoo.co.uk.
authors.forename: Kazeem A
authors.initials: KA
authors.lastname: Alayande
authors.affiliation: GI Microbiology and Biotechnology Unit, Agricultural Research Council, Animal Production Institute, Irene 0062, Pretoria, South Africa. Aiyegoroo@arc.agric.za.|Applied and Environmental Microbiology Research Group (AEMREG), Department of Microbiology and Biochemistry, University of Fort Hare, Alice, 5700, South Africa. Aiyegoroo@arc.agric.za.
authors.forename: Olayinka A
authors.initials: OA
authors.lastname: Aiyegoro
authors.affiliation: Department of Biological Science, Faculty of Agriculture and Technology, North West University, Mafikeng Campus, South Africa. sewizzy2009@yahoo.com.
authors.forename: Oluseun F
authors.initials: OF
authors.lastname: Akinpelu
authors.affiliation: Applied and Environmental Microbiology Research Group (AEMREG), Department of Microbiology and Biochemistry, University of Fort Hare, Alice, 5700, South Africa. Aokoh@ufh.ac.za.|SA-MRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, 5700, South Africa. Aokoh@ufh.ac.za.
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Okoh
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects* / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D003059:Cocos / Q000737:chemistry*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009711:Nucleotides / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D009711:Nucleotides; D010936:Plant Extracts; D011188:Potassium