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Research Article

Antibacterial activity of aqueous and methanol extracts of selected species used in livestock health management

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Pages 1054-1060 | Received 02 Jul 2016, Accepted 25 Jan 2017, Published online: 10 Feb 2017
 

Abstract

Context: Salvadora persica L. (Salvadoraceae), Colophospermum mopane (J.Kirk ex Benth.) J. Léonard (Leguminosae) and Dichrostachys cinerea (L.) Wight & Arn. (Leguminosae) crude extracts are used by local farmers against many livestock infections with little or no side effects usually associated with synthetic antimicrobials. However, their efficacy has rarely been tested.

Objective: These plants were tested for potential antibacterial activity against clinical isolates of Staphylococcus aureus ATCC33862 and Escherichia coli ATCC25922. Minimal inhibitory concentrations (MIC) of the crude plant extracts were determined.

Materials and methods: Aqueous and methanol extraction of 100 g each of the bark of C. mopane, roots of D. cinerea and leaves of S. persica was done by placing the samples in 250 mL of either water or methanol. Nutrient broth was used as growth medium for the bacteria, and McFarland standard for bacterial standardization. 2,3,5-Triphenyltetrazoliumchloride (TTC) was the indicator salt. Each of the aqueous and methanol extracts (100 μL) was tested. Gentamycin and ampicillin were the controls.

Results: MIC of aqueous extracts ranged from 1.03–14.6 mg/mL against S. aureus, and from 12.1–34.3 mg/mL against E. coli. Methanol extracts ranged between 5.31 and 9.64 mg/mL against S. aureus, and between 7.86 and 13.6 mg/mL against E. coli. Aqueous and methanol extracts of S. persica were significantly higher (p < 0.05) than C. mopane and D. cinerea.

Discussion and conclusion: Colophospermum mopane, S. persica and D. cinerea exhibited antibacterial activity, with methanol extracts performing better than aqueous extracts, justifying use as ethnoveterinary medicine. Further study to isolate the active components should be pursued.

Acknowledgements

This work was conducted within the framework of the Research Platform ‘Production and Conservation in Partnership’ (www.rp-pcp.org). We thank the French Ministry of Foreign Affairs for supporting this project through the FSP-RenCaRe project (FSP n°2011/36). We would also like to acknowledge Malipati traditional leadership for permission to conduct our study in their area. Special mention is extended to Stephen Chauke, Timoth Kuzomuka, Gregory Dowo, Cavin Nyati and Billy Butete for assistance during field work. Mrs Shuvai Musari and Peter Katsande from Central Veterinary Laboratory, as well as Mr Fanuel Jim and Ms Getrude Mashura from the Department of Veterinary Sciences, University of Zimbabwe are greatly appreciated for their help in laboratory analyses of plant samples.