Evaluation of antimicrobial and antioxidant activity of zinc oxide nanoparticles biosynthesized with Ziziphus spina-christi leaf extracts

Abstract

<b>Background:</b> Due to their simplicity, eco-friendliness, availability and non-toxicity, the greener fabrication of metal and metal oxide nanoparticles has been a highly attractive research area over the last decade. <b>Aim:</b> This study aimed to assess the antioxidant and antimicrobial activities of the green synthesized zinc oxide nanoparticles (ZnO-NPs) using an aqueous leaf extract of <i>Ziziphus spina-christi</i>. <b>Method:</b> The antioxidant property of ZnO-NPs was analyzed by the α, α-diphenyl-β-picrylhydrazyl (DPPH) and hydrogen peroxide (H₂O₂). Additionally, the diffusion agar method assessed the antimicrobial activities against bacteria and fungi. <b>Results:</b> ZnO-NPs synthesized by <i>Z. spina-christi</i> had shown promising H₂O₂ and DPPH free radical scavenging actions compared to vitamin C. The ZnO-NPs exhibited significant antibacterial activity against the tested bacteria with various susceptibility as a concentration-dependent effect. The largest zone of inhibition for <i>Staphylococcus aureus (S. aureus)</i> was observed (36 ± 2 mm) compared to <i>Escherichia coli (E. coli)</i> (15 ± 2 mm) by the same concentration of ZnO-NPs. The ZnO-NPs showed remarkable antifungal activity against <i>Aspergillus niger</i>. <b>Conclusion:</b> It can be concluded that, ZnO-NP have been imposed as suitable antimicrobial agent being able to combat both <i>S. aureus</i> and <i>E. coli in vitro</i>.