Phytochemical, Antioxidant and Antimicrobial Potentials of Azadirachta indica Leaf Extract Using Bacteria Isolated from Polluted Water as Test Organisms

Aims: Globally, there is continuous emergence of infectious pathogens. Therefore, there is a need to search for new drug molecules of plant origin such as A. indica which is commonly grown in Nigeria. This study was aimed at evaluating the antioxidant and antimicrobial potentials of the leaf extract of A. indica and determining its bioactive molecules.

Study Design: This was an in-vitro laboratory study.

Place and Duration of Study: This research was carried out at the Microbial Resources Research Laboratory (MRRL), Department of Pure and Applied Biology, Ladoke Akintola University of Technology, Ogbomoso Nigeria from April 2021 to January 2023.

Methodology: Collected fresh leaves of A. indica were destalked, air dried at 27oC for 10 days, and finally grounded. The dried powders were extracted by maceration using four (4) solvents namely: water (aqueous), methanol, ethyl-acetate, and n-hexane. The leaf extracts were assessed for their antioxidant and antimicrobial potential. Bioactive molecules present in the leaf extract were determined by Gas chromatography-mass spectrometry.

Results: It was observed that leaf extracts of A. indica possess bioactive molecules such as Phytol which is over 50% of the total biomolecules present. These biomolecules are responsible for the antimicrobial and antioxidant potentials of the extract. The ABTS and DPPH radicals scavenging activities ranged from 24.51 to 90.32 % and 31.79 to 79.59 % respectively. These extracts can be used to mop up free radicals which have damaging effects on the cells of the body. The minimum inhibitory concentration (MIC) of the extract for each of the test bacteria isolates varied between 0.05 to 0.8 mg/ml. Thus, the leaf extract of A. indica is a reservoir of bioactive molecules which can be used for novel drug synthesis and discovery.

Conclusion: Thus, leaf extracts of A. indica contain potent biomolecules which can be harnessed for therapeutic use.