Antibacterial, antibiofilm, and antioxidant activity of green synthesized silver nanoparticles by orange peel extract against pneumonia causing bacteria

Pneumonia is a common and serious disease that caused by many microbial pathogens with high morbidity and mortality rates. Nanotechnology became a new approach for treating the microbial infections. In this study, AgNPs were green synthesized by orange peel extract. The synthesized AgNPs were characterised. Ultraviolet-visible (UV-Vis) spectra of the produced nanoparticles showed a well- defined peak at 440 nm. TEM examination revealed the formation of spherical silver nanoparticles with a mean diameter of 17.1 nm, and X-ray diffraction (XRD) analysis confirmed the crystalline nature of such AgNPs with a face-centred cubic (FCC) pattern. FTIR analysis revealed the presence of function groups that could play a crucial role in reduction and stabilization processes. The synthesized AgNPs exhibited a remarkable antibacterial and antibiofilm activity with average inhibition zones against Escherichia Coli , Klebsiella pneumonia , and Staphylococcus haemolyticus estimated were 18, 14, and 23 mm respectively. Also, minimum inhibitory concentration (MIC) of green synthesized AgNPs revealed low concentration against tested bacteria ranged from 0.33 to 0.18 mg/ml and minimum bactericidal concentration (MBC) revealed results ranged from 0.77 to 0.31 mg/ml. In addition, a concentration of 5 mg/ml of AgNPs reduced the biomass of the preformed biofilms of E. coli (E3), klebsiella pneumoniae (K1), staphylococcus hemolyticus(S4) by 10.16%, 10.4% and 41.1%, respectively. Besides, the green-synthesized AgNPs have revealed good DPPH scavenging activity with IC₅₀ value of 60.72 µg/mL. Therefore, the green-synthesized silver nanoparticles in this study showed promising antibacterial and antibiofilm potency against tested bacteria causing pneumonia besides its antioxidant activity.