Ethnobotany and bioactivity of medicinal plants used to treat symptoms associated with gastro-intestinal infections in Namibia
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Date
2016
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Publisher
University of Namibia
Abstract
goal of the study was to determine the plants used in Namibia to treat symptoms linked to gastro-intestinal tract infections (GITI) and to verify their antimicrobial activity. An ethnobotanical survey was conducted to document plants used in Namibia to treat symptoms related to GITI, and eighteen plant species (from 16 families) were collected and identified. Aqueous and organic extraction methods were used to obtain crude extracts that were tested on Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Shigella sonnei by disk diffusion method. Lastly, fractionation by vacuum liquid chromatography was done on extracts of Terminalia sericea and Ximenia caffra and tested against E. coli, S. aureus and S. sonnei. Of these plants, T. sericea and Harpagophytum procumbens and Aloe sp. were the most mentioned plants used during the ethnobotanical survey. Some of the crude extracts tested had no inhibitory effect on any of the tested bacteria. Of the crude aqueous extracts tested, X. caffra and Moringa oleifera had the highest activity against B. subtilis, while H. procumbens and Parinari capensis were highly active against E. coli. Crude organic extracts from T. sericea and X. caffra showed the highest inhibitory effects against E. coli, S. aureus and S. sonnei and Acacia erioloba and Aloe sp. on B. subtilis. Furthermore, 20% methanol in Dichloromethane (DCM) and 10% acetone (in DCM) fractions from T. sericea had the most activity against S. aureus and S. sonnei respectively. The 100% methanol fraction and 10% acetone (in DCM) fraction from X. caffra were most effective against S. aureus and S. sonnei, respectively. Minimum inhibitory concentration of T. sericea root extract was lowest against S. aureus (0.1 mg/mL) and S. sonnei (1 mg/mL). From the results obtained, it is plausible that plants tested can be effective in treating some infections associated to GITI and are effective against both gram-positive and gram-negative microorganisms. These results show that the objectives were met. Additionally, as the most effective fractions were from T. sericea and X. caffra, conducting further research to determine the active compounds may be necessary.
Description
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Microbiology
Keywords
Medicinal plants, Gastro intestinal infections