ABSTRACT
Azadirachta indica is a very useful traditional medicinal plant in the sub-continent and each part of the tree has some medicinal properties. The plant is native to Asia, but has now naturalized in West Africa and is widely cultivated in Nigeria as an ornamental as well as medicinal plant. This study aimed at screening the active components and the antibacterial effects of the ethanolic leaf extract of Azadirachta indica. Fresh leaves of the plant were collected, dried, homogenized and extracted using 95% Ethanol. The extract was used for the phytochemical screening and bacterial susceptibility testing using cup-plate method.The result obtained from this study showed the presence of tannins, saponins, flavonoids, alkaloids, glycosides, reducing sugars and terpenes in the ethanolic leaf extract. The antibacterial effect produced by the extract was dose-dependent at the tested doses (6.25 mg, 12.5 mg, 25 mg, 50 mg and 100 mg) on Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella typhi (S. typhi). The minimum inhibitory concentration (MIC) for E. coli, S. aureus and S. typhi were 2.39 mg, 3.31 mg and 4.79 mg respectively. The effect produced by the ethanolic leaf extract at 100mg (18 mm) was statistically significantly higher than that of 1.5 mg ciprofloxacin (14 mm) on S. typhi (p<0.05). Azadirachta indica ethanolic leaf extract contains pharmacologically active constituents that may be responsible for its activity against S. aureus, E. coli and S. typhi. Therefore, the use of Neem plant in our community for treating diverse medical ailments especially infectious diseases is highly justified.