Biogenic synthesis and characterization of MgO nanoparticles using Verbascum sinaiticum: antibacterial, free radical, and reactive oxygen species scavenging activities

Abstract

The rapid occurrence and spread of antimicrobial-resistant bacteria pose a significant threat to global public health, increasing risks such as higher mortality rates, prolonged treatment durations, elevated healthcare costs, and reduced life expectancy. This pressing issue calls for innovative strategies to control microbial pathogens in food and environmental settings. Among these, nanomaterials have gained attention due to their exceptional durability, low toxicity, stability, and selectivity. In this study, we synthesized and characterized magnesium oxide nanoparticles (MgO NPs) using an aqueous extract of Verbascum sinaiticum leaves as a natural template and stabilizing agent. The crystalline nature, morphology, structural and functional groups, optical properties, stability, surface area and porosity of the synthesized Bio-MgO NPs were confirmed through X-ray diffraction analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, UV-visible spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and Brunauer–Emmett–Teller analysis. We evaluated the antibacterial properties of Bio-MgO NPs against both Gram-positive and Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes, and Staphylococcus aureus. The results demonstrated promising antimicrobial activity, with highest inhibition zones of 11.10 ± 0.53 mm, 12.35 ± 0.35 mm, 10.17 ± 0.51 mm, and 10.86 ± 0.20 mm, respectively, due to synergistic effects of the plant extract and MgO NPs. These findings highlight the potential of Bio-MgO NPs as effective antimicrobial agents against a broad spectrum of bacterial strains. Beyond their antibacterial properties, the antioxidant activity of Bio-MgO NPs was also assessed using DPPH and peroxide assays. Bio-MgO NPs exhibited excellent free radical (79.8–93.9%) and reactive oxygen species (75.5–89.3%) scavenging activity, comparable to ascorbic acid, used as the standard. These results suggest that Bio-MgO NPs have immense potential for diverse applications, including biomedicine, making them a promising candidate in the fight against antimicrobial resistance.