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

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dc.contributor.author Elisha, Ishaku Leo
dc.contributor.author Botha, Francien Susanna
dc.contributor.author McGaw, Lyndy Joy
dc.contributor.author Eloff, Jacobus Nicolaas
dc.date.accessioned 2017-04-20T15:42:43Z
dc.date.available 2017-04-20T15:42:43Z
dc.date.issued 2017-02-28
dc.description.abstract Background: 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.department Paraclinical Sciences en_ZA
dc.description.librarian am2017 en_ZA
dc.description.sponsorship The 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.uri https://bmccomplementalternmed.biomedcentral.com/ en_ZA
dc.identifier.citation Elisha, 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.issn 1472-6882
dc.identifier.other 10.1186/s12906-017-1645-z
dc.identifier.uri http://hdl.handle.net/2263/60000
dc.language.iso en en_ZA
dc.publisher BioMed Central en_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.subject Antibacterial activity en_ZA
dc.subject Potency en_ZA
dc.subject Efficacy en_ZA
dc.subject Cellular safety en_ZA
dc.subject Nosocomial bacteria en_ZA
dc.subject Correlation en_ZA
dc.subject Minimal inhibitory concentration (MIC) en_ZA
dc.title The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts en_ZA
dc.type Article en_ZA


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