Antimicrobial Effect of Leaf Extracts of Pigeon Pea (<i>Cajanus cajan</i>(L.) Millsp.) on Some Human Pathogens

Abstract

ABSTRACT Many human pathogens require serious attention in developing countries like Nigeria. Six pathogens were used for the study of the antimicrobial effect of Cajanus cajan leaf extract on some pathogens. Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Salmonella typhi, and Klebsiella pneumoniae were the bacteria isolates and Candida albicans was the only yeast (fungi) isolate used. Solvents used for the extraction of active ingredients of the plant leaf were water (as the aqueous solvent), petroleum ether, ethanol, and chloroform/methanol mixture (as organic solvents). The antibacterial effect of the plant extract showed that the organic solvent extracts were inhibitory to E. coli, S. aureus, and S. typhi; the aqueous extract was inhibitory to E. coli and S. aureus; while K. pneumoniae and P. mirabilis showed resistance to all the extracts. The minimum inhibitory concentration value of the extracts on the organisms ranged between 0.125 and 0.25 mg/ml for E. coli, 0.125 mg/ml for S. aureus and 0.0325–0.0625 mg/ml for S. typhi. Cidal or static effect varied with solvent type of extract, concentrations of the leaf extracts, and the organisms. The active components of the plant extract have no cidal or static effect on the tested yeast (C. albicans). The antimicrobial effect of leaf extracts of C. cajan is discussed in relation to the problem of drug resistance in developing countries like Nigeria.