Biosynthesis, characterization and antioxidant activity of oleuropein-mediated silver nanoparticles

Abstract

In this study, oleuropein was isolated from olive leaves by chromatographic method and its structure was elucidated by spectroscopic analyses such as FTIR, 1H-NMR and 13CNMR. Silver nanoparticles (AgNPs) were synthesized using oleuropein and their antioxidant activity was investigated using DPPH, ABTS•+, and FRAP assays. The AgNPs were characterized by UV-Vis, FT-IR, XRD, and SEM analyses. The absorption peak at 450 nm in UV-Vis spectrum confirmed the AgNPs formation. Scanning electron microscope (SEM) identified the formation of spherical-shaped nanoparticles with the average size of 71 nm. Rietveld analysis was carried out by X-ray diffraction data with High Score Plus software. XRD with 2θ degrees at 38.1°, 44.3°, 64.4° and 77.4° can be assigned to the (111), (200), (220) and (311) Bragg’s reflections of the face-centered cubic crystalline structure. Biosynthetic nanoparticles revealed more inhibitory effect (5.22, IC50, µg/mL) against ABTS•+ than standard BHT (7.03, IC50, µg/mL).