Abstract
Infectious diseases are important cause of morbidity and mortality due to continuous emergence of microbial resistance to conventional drugs. Acacia nilotica, Ziziphus jujube Linn and Lawsonia inermis are widely used for traditional medicine in Northern Nigeria. However, little is known about the biochemical and microbiological potentials of these indigenous plants. In this study, the plants leaves were screened for phytochemical and in vitro antimicrobial potentials using standard methods. Quantitative phytochemical analysis of crude methanolic leave extracts revealed high content of glycoside, tannins and phenols. High levels of saponins and flavonoids were also detected. The extracts exhibited antibacterial effects on Escherichia coli, Pseudomonas flourecense, Streptococcus and Staphylococcus aureus. At 50 mg/ml extract concentration, the zone of inhibition observed was greater than 6mm. This indicates high inhibitory potency of the plants leaves. In comparison to streptomycin sulphate, A. nilotica and L. inermis had statistically similar (P>0.05) effect on E. coli at 50 mg/ml. In general, the inhibitory effect of A. nilotica and L. inermis were higher than that of Z. jujube Linn in all concentrations, except on E. coli at 150 mg/ml. Both the extracts and control drug had minimum inhibitory concentration of 10 mg/ml for all the microbes tested except Streptococcus (20-25 mg/ml). Furthermore, the average Minimum Bactericidal Concentration was 15 mg/ml except for Streptococcus with 20-25 mg/ml. Methanol extracts of Acacia nilotica, Ziziphus jujube Linn, and Lawsonia inermis exhibit antibacterial effect, hence could be used as sources of potent agents against bacterial infection.

Key words: Antimicrobial, infectious disease, Methanol extract, Phytochemical.