INVESTIGATION OF ANTIBACTERIAL ACTIVITY OF ZNO NANO PARTCLES DRIVED FROM MANGO LEAF EXTRACT

ABSTRACT Nanotechnology has emerged as a promising field for developing novel antimicrobial agents capable of addressing the growing challenge of multidrug-resistant microorganisms. In this study, zinc oxide (ZnO) nanoparticles were synthesized using mango (Mangifera indica) leaf extract through an eco-friendly green synthesis approach. The mango leaf extract served as a natural reducing and stabilizing agent due to its rich phytochemical composition, as confirmed by qualitative screening which indicated the presence of terpenoids, alkaloids, phenols, flavonoids, tannins, saponins, and cardiac glycosides. The formation of ZnO nanoparticles was confirmed by UV–Visible spectroscopy, which showed a characteristic absorption peak at 372 nm, indicating successful nanoparticle synthesis. The antibacterial activity of the synthesized nanoparticles (coded KM1 and KM2) was evaluated using the agar well diffusion method against four bacterial species: Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Salmonella typhi. The results demonstrated that both KM1 and KM2 exhibited concentration-dependent antibacterial activity. KM1 showed the highest inhibition zone against Salmonella typhi (15 mm at 20 mg/mL), followed by moderate activity against Streptococcus pyogenes and E. coli. KM2 displayed similar activity patterns but with no effect on Staphylococcus aureus. Both nanoparticle formulations showed reduced activity at lower concentrations (10 mg/mL), confirming dose responsiveness. Staphylococcus aureus was resistant to both preparations.