Evaluation of antibacterial activity and phytochemical investigation of Azadirachta indica L. against certain bacterial species

Abstract

Historically, plants have been a source of herbal medicines and are used for treating various human ailments. Azadirachta indica, commonly known as neem, is a multipurpose tree with a wide range of health benefits. Various parts of neem tree have been shown to exhibit antimicrobial effects against a wide variety of microorganisms. The present study was carried out for screening of active components and antibacterial activity of leaves and bark extracts of A. indica. Ethanol and methanol extracts of leaves and bark of A. indica were tested against Gram positive and Gram negative bacteria viz. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus cereus. The agar well diffusion method was used for testing the antibacterial activity. Results revealed that methanol extract of bark and ethanolic extract of leaves exhibited significant antibacterial activity. Methanolic extract of bark of A. indica showed maximum antibacterial activity against B. cereus and K. pneumoniae (16 mm) followed by p. aeruginosa (15.6 mm), E. coli (15.3 mm) and least was found against S. aureus (15 mm). Whereas ethanolic extract of leaves exhibited maximum activity against P. aeruginosa (11.3 mm), followed by K. pneumoniae (11 mm), S. aureus (10.3 mm), E.coli (7 mm) and no activity was observed against B. cereus. Phytochemical screening of plant extracts gave positive results for alkaloids, flavonoids, saponins and tannins.