The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts

dc.contributor.authorElisha, Ishaku Leo
dc.contributor.authorBotha, Francien Susanna
dc.contributor.authorMcGaw, Lyndy Joy
dc.contributor.authorEloff, Jacobus Nicolaas
dc.contributor.emailkobus.eloff@up.ac.zaen_ZA
dc.date.accessioned2017-04-20T15:42:43Z
dc.date.available2017-04-20T15:42:43Z
dc.date.issued2017-02-28
dc.description.abstractBackground: The development of antibiotic resistant bacteria stems from a number of factors, including inappropriate use of antibiotics in human and animal health and their prolonged use as growth promoters at sub-clinical doses in poultry and livestock production. We were interested in investigating plants that could be useful in protecting humans or animals against diarrhoea. We decided to work on extracts of nine plant species with good activity against Escherichia coli based on earlier work in the Phytomedicine Programme. Leaves of nine medicinal plant species with high antibacterial activity against Escherichia coli were extracted with acetone and their minimal inhibitory concentration (MIC) values determined using a microplate serial dilution technique against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria. Bioautography was used to determine the number of bioactive compounds in each extract. In vitro safety of the extracts was determined using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay on Vero cells. Results: The extracts were active against all the pathogens with average MICs ranging from 0.02 to 0.52 mg/ml. As expected E. coli was relatively sensitive, while E. faecalis and S. Typhimurium were more resistant to the extracts (average MICs of 0.28 mg/ml and 0.22 mg/ml respectively). Cremaspora triflora and Maesa lanceolata leaf extracts had higher activity than the other extracts against Gram-positive and Gram-negative pathogens with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum had the highest total antibacterial activity (TAA) at 1417 and 963 ml/g respectively. All extracts with the exception of that of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea had relatively low cytotoxicity with LC50 >20 μg/ml. Cremaspora triflora had the best selectivity index (SI) against S. aureus and E. coli of 2.87 and 1.15 respectively. Hypericum roeperianum had a SI of 1.10 against B. cereus. Bioautography revealed 1–6 visible antimicrobial compounds that were generally non-polar. Conclusions: There was a weak positive, but statistically non-significant correlation between the potency of the extracts and their cytotoxicity (R= 0.45, ρ > 0.05). The activity of the extracts on the test bacteria was in some cases not correlated with cytotoxicity, as shown by selectivity indices >1. This means that cellular toxicity was probably not due to compounds with antibacterial activity. Some of the extracts had a good potential for therapeutic use against the bacterial pathogens or for application in treating diarhoea. It does not appear that activity against E. coli is a good predictor of activity against Gram-negative rather than Gram-positive bacteria. Further investigation is in progress on C. triflora and H. roeperianum, both of which had promising activities and potential safety based on cytotoxicity.en_ZA
dc.description.departmentParaclinical Sciencesen_ZA
dc.description.librarianam2017en_ZA
dc.description.sponsorshipThe National Research Foundation of South Africa (Eloff IPPR 953991), the Medical Research Council of South Africa and the University of Pretoria.en_ZA
dc.description.urihttps://bmccomplementalternmed.biomedcentral.com/en_ZA
dc.identifier.citationElisha, IL, Botha, FS, McGaw, LJ & Eloff, JN 2017, 'The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts', BMC Complement​ary and Alternativ​e Medicine, vol. 17, art. no. 133, pp. 1-10.en_ZA
dc.identifier.issn1472-6882
dc.identifier.other10.1186/s12906-017-1645-z
dc.identifier.urihttp://hdl.handle.net/2263/60000
dc.language.isoenen_ZA
dc.publisherBioMed Centralen_ZA
dc.rights© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License.en_ZA
dc.subjectAntibacterial activityen_ZA
dc.subjectPotencyen_ZA
dc.subjectEfficacyen_ZA
dc.subjectCellular safetyen_ZA
dc.subjectNosocomial bacteriaen_ZA
dc.subjectCorrelationen_ZA
dc.subjectMinimal inhibitory concentration (MIC)en_ZA
dc.titleThe antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extractsen_ZA
dc.typeArticleen_ZA

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