Comparative evaluation of antibacterial activity of induced and non-induced Cajanus cajan seed extract against selected gastrointestinal tract bacteria

Gastrointestinal tract (GIT) infections are major causes of mortality and morbidity world-wide, especially in developing countries. Cajanus cajan extracts possess therapeutic properties. In this study, the induced and non-induced antibacterial properties of C. cajan seeds were evaluated against bacterial strains implicated in GIT infections by Disc diffusion method and Micro-well dilution assay. C. cajan produced phytoalexins after the seeds were elicited with native flora and silver nitrate. At 100 mg/ml, the ethyl acetate extract produced zones of inhibition (14 to 16 mm) against Staphylococcus aureus (ATCC 25925), Klebsiella pneumoniae (ATCC 31488) and Salmonella typhimurium (ATCC 700030). The minimum inhibitory concentration (MIC) values obtained using micro well dilution method were 6.5, 12.5, and 12.5 mg/ml for S. aureus (ATCC 25925), K. pneumoniae (ATCC 4352) and S. typhimurium (ATCC 700030) and 25 mg/ml for all bacterial strains in the ethyl acetate extract (AgNO3 induced seeds), respectively. The results thus indicated that C. cajan seed extract do possess antibacterial activity.