Asian Journal of Biotechnology and Genetic Engineering

Antimicrobial resistance and oxidative stress-related disorders have increased the need for multifunctional bioactive materials. This study synthesised iron-manganese (Fe-Mn) bimetallic nanoparticles using aqueous Mangifera indica leaf extract and evaluated their antibacterial and antioxidant activities. Fe-Mn nanoparticles were prepared by mixing aqueous Fe²⁺ and Mn⁷⁺ salt solutions with M. indica leaf extract. The synthesised nanoparticles were characterised using UV-Visible and Fourier-transform infrared spectroscopy. Antibacterial activity was assessed by agar well diffusion, minimum inhibitory concentration and minimum bactericidal concentration assays against Escherichia coli, Salmonella typhi, Klebsiella pneumoniae and Pseudomonas aeruginosa. Antioxidant activity was determined using DPPH and ABTS radical scavenging assays. UV-Visible analysis showed a surface plasmon resonance peak at 450 nm, while FTIR analysis indicated functional groups including O-H, C=O and Fe-O/Mn-O, suggesting nanoparticle formation and phytochemical involvement in reduction and stabilisation. The nanoparticles produced inhibition zones of 15.00 mm against S. typhi, 14.90 mm against K. pneumoniae, 14.83 mm against E. coli and 7.13 mm against P. aeruginosa. The MIC was 12.5 µg/mL for all tested organisms, while MBC values ranged from 25 to 50 µg/mL. In the DPPH assay, Fe-Mn nanoparticles showed 28.25% inhibition at 6.25 µg/mL and an IC₅₀ of 23.74 µg/mL. In the ABTS assay, maximum inhibition was 51.65% at 60 µg/mL. The findings indicate preliminary antibacterial and antioxidant potential under the tested laboratory conditions.