Evaluation of Brine shrimp lethality and Antimicrobial activity of Azadirachta indica leaf extract on some drug resistance bacteria in Bangladesh

Azadirachta indica (Neem) is very useful traditional medicinal plant in the subcontinent. Each part of the tree has some medicinal properties. In this present studies the bioactivity and antimicrobial activity of Azadirachta indica leaf extract was evaluated. For bioactivity, Brine shrimp lethality test was done for A. indica ethanolic leaf extract and determined LC50 was 37.15 μg/ml indicating that the prepared extract was rich in bioactive compounds. Ethanolic leaf extract was also used to evaluate antibacterial activity and the extract exhibited significant activity against the tested bacterial strain. However, inhibitory activity was concentration and test organism dependent. Gram-positive bacteria were more sensitive to the extract compare to Gram-negative bacteria. All of the tested bacteria showed sensitivity at higher concentration (7mg/ml) but multi drug resistant bacteria Klebsiella pneumoniae was very sensitive even at very low concentration (2mg/ml). Further, the results depict that leaf extracts of Azadirachta indica could be used as a potential source of antimicrobial agents against the bacterial strains tested.