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, IC_50, µg/mL) against ABTS^•+ than standard BHT (7.03, IC_50, µg/mL).

Keywords:

• Nanoparticles
• oleuropein
• antioxidant activity
• natural product

Conflict of interest

The authors did not declare any conflict of interest.

Additional information

Funding

The authors are thankful to the Tokat Gaziosmanpasa University, Scientific and Research Fund for financial support (BAP-2017-31).