Comparative Study of Antimicrobial and Antioxidant Potential of Olea ferruginea Fruit Extract and Its Mediated Selenium Nanoparticles

Abstract

Nanotechnology, the science of the recent era, has diverse applications in agriculture. Selenium (Se) is a non-metal and an essential micronutrient for animals and humans. In this study, selenium nanoparticles (SeNPs) were biosynthesized by using Olea ferruginea fruit extracts. The size, shape, chemical nature, and identification of functional groups involved in the synthesis of SeNPs were studied by UV-visible spectroscopy, Scanning Electron Microscope (SEM), and Fourier Transform Infra-Red (FTIR) spectrometry. SeNP synthesis was confirmed by an absorption peak at 258 nm by UV-visible spectroscopy. SEM showed that SeNPs were spherical, smooth, and between 60 and 80 nm in size. FTIR spectrometry confirmed the presence of terpenes, alcohols, ketones, aldehydes, and esters as well as phyto-constituents, such as alkaloids and flavonoids, that possibly act as reducing or capping agents of SeNPs in an aqueous solution of Olea ferruginea. Antimicrobial activity was examined against bacterial pathogens, such as Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermitis, as well as fungal pathogens, such as Aspergillus niger and Fusarium oxysporum, by using the well-diffusion method. Antioxidant activity was observed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, ABTs assay, and reducing power assay. At a higher concentration of 400 ppm, biosynthesized SeNPs showed an inhibition zone of 20.5 mm, 20 mm, 21 mm, and 18.5 mm against Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermitis, respectively. Similarly, SeNPs also demonstrated a zone of inhibition against Aspergillus niger and Fusarium oxysporum of 17.5 and 21 mm, respectively. In contrast to Olea ferruginea fruit extracts, Olea ferruginea-mediated SeNPs demonstrated strong antimicrobial activity. By performing the DPPH, ABTs, and reducing power assay, SeNPs showed 85.2 ± 0.009, 81.12 ± 0.007, and 80.37 ± 0.0035% radical scavenging potential, respectively. The present study could contribute to the drug development and nutraceutical industries.