Phytochemical Analysis and Antimicrobial Activity of Methanolic, Ethanolic and Acetonic Extracts of Stem Bark and Leaf of Neem Plant (Azadirachta indica)

This study was carried out on phytochemicals and in vitro screening of antibacterial potentials of ethanolic, methanolic and acetonic extracts of stem bark and leaves of Neem plant (Azadirachta indica) by using the methods of AOAC; and agar diffusion technique. The extracts of the leaves and the stem bark were prepared and screened for the presence of different phytochemicals. The results obtained showed that both the leaf and stem bark extracts contain alkaloid, flavonoid, reducing sugar, tannin, saponin and polyphenol. The extracts were tested against selected pathogens; Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus niger, Aspergillus fumigatus and Candida albicans by using agar well diffusion technique. In this present research work, the acetonic, ethanolic and methanolic leaves and bark extracts of Neem plant were investigated for antimicrobial activity against these selected pathogens. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. The MIC for the bacterial isolates was 25 mg / ml of the leaf extracts and that for stem bark was 6.25 mg / ml. The MBC was 25 mg / ml. Results showed that the bark extract exhibited strongest antimicrobial activity against bacteria and fungi at different concentrations when compared with the activity of the leaf extract. The acetonic stem bark extract had the highest antibacterial activity with a zone of inhibition of 22 mm, and then followed closely by the stem bark's ethanol extract with a zone of inhibition of 21 mm. More so, the methanolic stem bark extract had the highest antifungal activities with a zone of inhibition of 22.50 mm. Thus, this work showed that both leaf and stem bark extracts had some phytochemicals and antimicrobial activity.