Antimicrobial activities of Cajanus cajan L., Phaseolus vulgaris L. and Vigna unguiculata L. against some bacterial and fungal isolates

Abstract

Clinical failures associated with synthetic chemotherapies have turned the search for novel natural antimicrobial agents by pharmaceutical and food industries, in the direction of bioactive phytochemical compounds. The antimicrobial activities of Cajanus cajan, Phaseolus vulgaris and Vigna unguiculata against some selected bacterial and fungal isolates were evaluated. This was done by ethanolic extraction of the plant seeds, which were air-dried at room temperature after extraction and collected in sterile test tubes. Agar well diffusion method was adopted for the antimicrobial susceptibility test against two bacterial isolates (Listeria ivanovii and Escherichia coli), and two fungal isolates (Aspergillus fumigatus and Candida albicans). This study indicated that P. vulgaris extract demonstrated the highest antimicrobial activity among the three extracts tested. Comparatively, Vigna unguiculata exerted the lowest antimicrobial effect on all the test isolates. MIC results indicated that C. cajan inhibited all the strains tested (100%) at the presented concentrations. While P. vulgaris inhibited 75% of the isolates, only 50% of the strains was inhibited by V. unguiculata. These activities decreased with the extract concentrations. The plants’ ability to inhibit both bacteria and fungi suggests that they have broad spectrum antimicrobial activities. Although more studies are needed to further authenticate our findings, our finding is interesting considering that these plants are regularly consumed as foods and could be added to the growing list of useful plants materials/products for the treatment of infectious diseases.