Phytochemical Analysis and Antibacterial Activity of Azadirachta indica Leaf Extracts against Escherichia coli

Background: Traditional medicine has employed Azadirachta indica to treat a variety of ailments. However, there is little information on the use of this plant in Zambia. Objective: To evaluate the phytochemicals and antibacterial activity of Azadirachta indica leaf extracts against Escherichia coli. Materials and Methods: This was a laboratory-based experimental study in which ethanol and water were used for extraction by maceration. Phytochemical analysis was then done on the leaf extract. Using the disc diffusion method, varying concentrations of A. indica aqueous and ethanolic extracts were used to test the antibacterial activity of A. indica against Escherichia coli. The sensitivity of the tested microorganisms to aqueous and ethanolic leaf extracts was shown by zones of inhibition after incubation. Results: The phytochemical screening of the A. indica leaves revealed the presence of phenolics and tannins in both the ethanol and aqueous extract. Saponins, flavonoids and alkaloids were only present in the aqueous extract. While steroids were only present in the ethanol extract. The antibacterial activity of A. indica leaves extract was determined by zones of inhibition which showed that both aqueous and ethanol extracts had activity against E. coli. The Minimum Inhibitory Concentration was determined at 10 mg/mL for the aqueous extract and 20 mg/mL for the ethanol extract. The zones of inhibition in-creased with concentration. Conclusion: The extracts of A. indica displayed antibacterial activity against E. coli in a dose-dependent manner. Compara-tively, the aqueous extract produced better antibacterial properties against E. coli than the ethanolic extract.