Abstract

ANTIMICROBIAL ACTIVITY OF CRUDE EXTRACTS OF PITHECELLOBIUM DULCE BARK AGAINST VARIOUS HUMAN PATHOGENIC MICROBES

Mukesh Kumar and Kiran Nehra*

ABSTRACT

Different organic solvent and aqueous extracts of bark of Pithecellobium dulce Benth. (Leguminosae), prepared in increasing and decreasing order of polarity were screened for their antimicrobial activity against human pathogenic bacteria (twelve) and fungi (eight) using agar well diffusion assay. The pattern of inhibition was found to vary with the solvent used for extraction and the microorganisms tested. However, most of the organic solvent extracts, viz., benzene, chloroform, acetone, and methanol showed significant antimicrobial activity (ranging between 6.0 to 25mm) against the tested microbes. Most of the extracts showed a higher activity against the fungal strains as compared to the bacterial strains. Chloroform and benzene extracts were found to exhibit inhibition of a wider range of bacterial strains; however, the highest zone of inhibition (16 mm) was recorded by the methanol extract against S. epidermidis. In contrast, the fungal strains were more susceptible to acetone and methanol fractions; the highest activity being reported by the acetone extract against A. niger. The broth microdilution assay gave minimum inhibitory concentration (MIC) values ranging between 250 μg/ml to 1000 μg/ml. Very low MIC values were obtained for E. faecalis &M. luteus bacterial strains, and for A. flavus & A. niger fungal strains; indicating the sensitivity of these strains to the various solvent extracts. Preliminary phytochemical analysis of the extracts showed the presence of alkaloids, anthraquinones, terpenoids and sterols in all extracts. The results of the present study show that Pithecellobium dulce bark extracts possess bioactive compounds having significant antimicrobial activity, making it a potential natural source of new antimicrobial agents.

Keywords: Pithecellobium dulce, antimicrobial, human pathogens, phytochemical analysis