Generation and Characterization of Silver Nanoparticles in Mentha pulegium Extract and Evaluation of Biological Activities of the Prepared Extract

Abstract

The aim of the present study was to synthesize silver nanoparticles (AgNPs) using Saudi Mentha pulegium leaves, to characterize the physicochemical properties of the resulting AgNPs, and to evaluate the biological activities of the resulting AgNP-containing extract. The formation of AgNPs in M. pulegium extract was indicated by a change in color following the addition of silver nitrate and was confirmed using UV-visible spectroscopy with a maximum absorbance at 425 nm. Energy dispersive X-ray spectroscopy (EDX) indicated that the anisotropic AgNPs were spherical, and Fourier transform infrared spectroscopy (FTIR) spectral analysis indicated that the aqueous M. pulegium extracts were responsible for reducing Ag+ to Ag0. The secondary metabolite contents of the methanolic M. pulegium extract corresponded to 17 mg GAE/g DW. DPPH and ABT radical-scavenging assays indicated that the M. pulegium extracts possessed antioxidant activity (IC50=6and 3 μg/mL, respectively). Disc and broth dilution assays revealed that the extracts exerted significant antibacterial activity, with the inhibition zone diameters and minimal inhibition concentrations of 17–24 mm and 0.08–0.62 mg/mL, respectively. These findings clearly indicate that modified plant extracts have high biological importance and potential use as preservatives in the pharmaceutical and food industries.