Antibacterial Activities of Leaf Extracts of Jatropha tanjorensis Ellis and Saroja (Euphorbiaceae)

Abstract

The need to substantiate the widely acclaimed antibacterial potentials of Jatropha tanjorensis leaf, informed the present study. Two extract types of the plant’s leaf (an ethanolic, JELE, and aqueous extract, JALE) were prepared and analysed for phytochemical constituents following standard protocols. Three concentrations of each extract (30, 40 and 50 mg/ml) were assayed on two bacteria species, Escherichia coli and Staphylococcus aureus. Results revealed the presence of six bioactive compounds, which varied with extract type. The compounds include alkaloid, saponin, steroid, tannin, phenol and anthraquinone; five were found in JELE, while four in JALE. Antibacterial analyses showed a dose and bacterial-species dependent activities of the extracts. JALE showed higher activities on the organisms at all concentrations, while JELE had no activities on E. coli at lower concentrations. Staphylococcus aureus was susceptibility to all concentrations of JELE (range=8.67±3.6 to 15.03±0.95 mm) and JALE (12.80±0.98 to 20.33±1.53 mm). Minimum Inhibitory Concentration (MIC) of the JALE was 7.5 mg/ml for both species of bacteria, while JELE had MIC of 15 and 25 mg/L for S. aureus and E. coli, respectively, while Minimum Bactericidal Concentration (MBC) analyses showed the leaf extracts to be bacteriostatic in activity. These results suggest that the leaf extracts are active against the two bacteria studied and JELE more potent than JALE. These extracts could be of value in the management of disease conditions associated with these bacteria.