Evaluation of antimicrobial activity of three important medicinal plants of South India

India is found to be a country with rich biodiversity and enormous treasure of herbal plants and consequently called as medicinal garden of the world. Plants are the richest source of natural antimicrobial agents. In recent years drug resistance to human pathogenic bacteria has been commonly reported from all over the world. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infectious diseases; one approach is to screen local medicinal plants for possible antimicrobial properties. The present study was designed to evaluate the antimicrobial efficacy of hexane, chloroform and methanol crude extracts of the leaves of three important medicinal plants viz., Biophytum sensitivum (L.) DC , Bougainvillea spectabilis L. and Caesalpinia bonducella (L.) Fleming, collected from in and around Visakhapatnam District. The antimicrobial activity of the crude extracts was tested against three Gram Positive bacteria ( Bacillus subtilis MTCC 441, Enterococcus faecalis MTCC 439, Staphylococcus aureus MTCC 737), Three Gram Negative bacteria ( Escherichia coli MTCC 443, Proteus vulgaris MTCC 426 and Pseudomonas aeruginosa MTCC 1688) and three Fungal strains ( Candida albicans MTCC 227, Epidermophyton floccosum MTCC 613 and Trichophyton mentagrophytes MTCC 7687) using agar well diffusion assay. Our results demonstrated that methanol extracts of these plants leaves have concentration dependent antibacterial activity against some of the tested organisms. Further studies should be undertaken to elucidate the exact mechanism of action of antimicrobial effect to identify the active ingredients which can be used for drug development program.