Phytochemical Screening And Antibacterial Testing Of Selected Namibian Medicinal Plants Against Laboratory And Clinical Bacteria That Cause Diarrhoea

ABSTRACT

Medicinal plants are rich in a wide variety of bioactive compounds associated with various ailments; including antibacterial activity and some of them have been used worldwide in traditional settings to treat diarrheal diseases. However evidence on safety and efficacy of some of these traditional medicinal plants is lacking, preventing their mainstream use. This study aimed at determining the antibacterial activity of Boscia albitrunca, Ziziphus mucronata, Combretum apiculatum, Solanum linnaeanum and Terminalia sericea against clinical and laboratory diarrheal pathogens and screen selected plants for the presence of major phytochemical compound. Plant parts (bark, roots and twig) were collected from Kunene region and extracted using aqueous and organic solvents and screened for the presence of triterpenoids, saponins, flavonoids, steroids, coumarins, tannins and alkaloids by thin layer chromatography (TLC). Antibacterial activities of the organic and aqueous extracts were determined against laboratory strains of Escherichia coli, Shigella bodyii, Staphylococcus aureus and Listeria monocytogenes and clinical strains of Salmonella, E. coli and Shigella, by disc diffusion method at three different concentrations (250, 500 and 1000 µg/ml). The average inhibition zones were determined on Mueller- Hinton agar plates. Phytochemical screening revealed higher presence of antibacterial compounds triterpenoids, saponins, flavonoids, steroids, coumarins and alkaloids in organic extracts and tannins in aqueous extracts. The organic extracts of T. sericea showed broad spectrum antibacterial activity against both clinical and laboratory diarrheal pathogens.