Phyto-mediated synthesis of MgO nanoparticles using Melia azedarach seed extract: Larvicidal and antioxidant activities

Plants contain some oxygen-containing phyto-components that possess medicinal values such as antioxidant and antipathogenic compounds. These oxygen-containing compounds such as flavonoids could be utilized in the synthesis of nanoparticles, thereby circumventing the use of toxic chemicals in materials synthesis. In this report, an eco-friendly green synthesis route has been employed to synthesize MgO nanoparticles (NPs) using the aqueous extract of Melia azedarach seed as the stabilizing agent. Different volumes (5, 10, and 20 mL) of the extract were used to synthesize nanoparticles represented as (b) MgONPs @5 mL, (c) MgONPs @10 mL (d) MgONPs @20 mL, respectively. The crystallinity and crystalline sizes were confirmed by an X-ray diffractometer, while the external and internal morphology of the NPs was evaluated using scanning and transmission electron microscopy. The band gap energies of the NPs were found to be in the range of 5.08 - 5.28 eV. Fourier-transform infrared spectroscopy was used to ascertain the type of functional groups that could be responsible for the synthesis. Larvicidal activity of the NPs was assessed against third instar larvae of Aedes aegypti and showed a dose-dependent activity against the larvae, with MgONPs @20 mL exhibiting the highest mortality of 86.68% at a concentration of 90 μg/mL and the least activity of 6.68% at 12.5 μg/mL concentration. Antioxidant assay of the NPs was evaluated, and the results indicated an increase in the percentage of radicals scavenged by the MgONPs compared to the plant extract. This was ascribed to the possible chelation of the radicals on the large surface area of the nanoparticles. The study shows the potential of M. azedarach seed-mediated MgO NPs to be utilized upon further study as high potent larvicidal and antioxidant agents in the development of novel nanoparticle-based biomedical agents.