Phytochemical and antibacterial activities of <i>Vitellaria paradoxa</i> and <i>Sclerocarya birrea</i> stem bark and leaves

Abstract

Increasing resistance developed by many bacterial species has been reported to commonly prescribed antibiotics for bacterial infections. Therefore, the need to search for natural products for remedy of this problem cannot be overemphasized. The aim of the study was to evaluate the phytochemical and antibacterial activities of Vitellaria paradoxa and Sclerocarya birrea ‘stem barks and leaves’ extracts against some human pathogenic bacteria. The methanol and aqueous extracts of Vitellaria paradoxa and Sclerocarya birrea stem barks and leaves were carried out using cold maceration extraction method. Phytochemical screening and acute toxicity studies were carried out using standard methods. Agar well diffusion and agar dilution methods were employed to determine the zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC). Phytochemical screening revealed the presence of alkaloids, flavonoids, saponins, tannins, steroid, carbohydrates and triterpenes in both aqueous and methanolic extracts. All the extracts showed broad spectrum of activity at 500 mg/ml but the methanol extract had larger zones of inhibition and lower M.I.C and M.B.C values ranging from 15.125 mg/ml and 31.25 mg/ml against Staphylococcus aureus and Escherichia coli. The LD₅₀ of Vitellaria paradoxa and Sclerocarya birrea stem barks and leaves were found to be greater than 5000 mg /kg and could be considered safe for consumption. This study has justified the traditional use of Vitellaria paradoxa and Sclerocarya birrea stem barks and leaves extracts in the treatment of infections caused by bacteria. Further investigations should be carried out to isolate pure compounds and determine the mechanisms of action of the plant.