Differential Antimicrobial Effects of Conventional and Ethnobotanical Extracts from Vitellaria paradoxa Roots, Barks and Leaves

Abstract

Aims: To determine the antimicrobial potentials of leaves, roots and barks of Vitellaria paradoxa “Shea-nut tree” used in traditional medicine for treatment of stomach ache and control of diarrhea. Place and Duration of Study: Department of Microbiology, Federal University of Agriculture Abeokuta, Ogun State, P.M.B 2240, Nigeria, between August 2010 and May 2011. Methodology: The leaves, roots and leaves were extracted by four solvents: methanol, omidun, sterile-omidun and aqueous. These extracts were tested for antimicrobial activities at different concentrations (100 mg/ml, 50 mg/ml and 25 mg/ml respectively) against some gastroenteric organisms using the disc diffusion assay. The test organisms used are typed culture E. coli ATCC 25922 and clinically isolated Enteropathogenic E. coli, Enterohaermohargic E. coli, Salmonella typhi and Shigella flexneri. The extractants served as negative control while loperamide antibiotics served as positive control. Results: Generally, all the extracts exhibited varying antimicrobial activities against the test organisms with most of them exhibiting low Minimum Inhibitory Concentration (MIC). There was significant difference (p<0.05) in the effects of each of the extracts when used at different concentrations. The higher the concentration of extract, the wider the zone of inhibition. Methanol extracts showed the highest potency (19.0 mm for bark and 6.67 mm for root) followed by omidun extracts (17.33 for bark and 4.67 mm for root). Aqueous and sterile omidun extracts produced low inhibition at high concentration and no inhibition at low concentrations. At 100 mg/ml methanol extraction, the bark of Shea butter tree gave the highest potency (13.67–19.00 mm) followed by extracts of leaves (11.33-16.70 mm) while the extracts of roots had the lowest potency (6.67-17.00 mm). Conclusion: Extracts of this plant parts have antimicrobial effects on the tested enteric bacteria, hence serve as potential therapeutic agent against diarrhea.