Phytochemical Analysis and Antimicrobial Efficacy of Leaf Extracts of Pithecellobium Dulce

The present study was designed to evaluate the antimicrobial activity of leaf of Pithecellobium dulce against twenty pathogenic microorganisms. Leaf extracts of P. dulce were prepared in distilled water and organic solvents, viz., benzene, chloroform, acetone and methanol in increasing and decreasing order of solvent polarity. Agar well diffusion technique was used to assess the antimicrobial activity of leaf extracts against five Grampositive (Bacillus subtilis, Enterococcus faecalis, Micrococcus luteus, Staphylococcus aureus and Staphylococcus epidermidis), seven Gram-negative (Aeromonas hydrophila , Alcaligenes faecalis, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella typhimurium) bacteria and eight fungi (Aspergillus flavus, Aspergillus niger, Aspergillus oryzae, Aspergillus terreus, Alternaria alternata, Alternaria brasicola, Alternaria solani and Alternaria vitis). The extracts showed variable inhibition zone (ranging between 7 to 27mm) against most of the tested microbes. Solvent extracts were found to be more effective than the aqueous extract. The most susceptible microorganism was E. faecalis exhibiting a zone of inhibition of 27mm. The broth microdilution assay gave minimum inhibitory concentration (MIC) values ranging from 200 to 1000 μg/ml. The lowest MIC values were obtained against E. faecalis, indicating the susceptibility of the strain for all the extracts. Preliminary phytochemical analysis of different extracts revealed the presence of alkaloids, anthraquinones, flavonoids, cardiac glycosides, proteins, tannins, sugars, and terpenoids. The results of the present study indicate that Pithecellobium dulce extracts possess bioactive compounds having significant antimicrobial properties. Hence, the plant extracts can be subjected to further isolation of therapeutic antimicrobial agents for pharmacological evaluation.