Green synthesis of gold nanoparticles using aqueous extract of <i>Haplophyllum canaliculatum</i> Boiss and its antioxidant activity

Abstract

Green synthesis of gold nanoparticles (AuNPs) is increasingly popular due to their broad potential applications. Hence, this research reports the synthesis of AuNPs by reducing of HAuCl4 using an aqueous extract of Haplophyllum canaliculatum Boiss as both a reducing and stabilizing agent. In addition, the antioxidant activity of as-prepared AuNPs was investigated. The physicochemical properties of AuNPs were characterized by UV-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The UV-Vis spectra displayed a surface plasmon resonance band at 523 nm, which confirmed the formation of AuNPs. Also, the FESEM image revealed that the particle sizes of the AuNPs ranged from 15 to 25 nm. In addition, the Debye-Scherrer equation showed a particle size of 16.4 nm from the XRD result. Furthermore, the biosynthesized AuNPs exhibited significant antioxidant activity (P< 0.05) against DPPH free radicals' scavenger in a concentration-dependent manner . The IC50 value of the AuNPs was obtained as 44.42 µg mL-1. The antioxidant activity of the AuNPs likely stems from secondary metabolites of the H. canaliculatum extract, such as quinoline alkaloids. These findings offer a promising approach for developing biosynthesized AuNPs for potential pharmaceutical applications.