SYNTHESIS OF SILVER NANOPARTICLES USING A NOVEL STEM EXTRACT OF ANABASIS LACHNANTHA and THEIR INSECTICIDAL, ANTIOXIDANT, and ANTIMICROBIAL EFFECTS

Abstract

Biogenic fabrication of metallic nanoparticles is an emerging discipline for the production of nanoproducts that exert potent antioxidant and antibacterial activity, and do not suffer from the limitations inherent in physicochemical synthesis methods. A sustainable and environmentally beneficial method is the synthesis of green nanoparticles using various plant extracts. This study developed a direct method for synthesizing silver nanoparticles (AgNPs) using methanolic, ethanolic, and aqueous extracts of Anabasis lachnantha Aellen and Rech., which served as both reduction and capping agents. AgNPs production was optimized by using different pH levels (ranging from 0 to 14), temperature variations (25°C to 95°C), and the addition of 1 mM salt solutions (0.2 to 1 mL). The UV-Vis spectroscopy data showed that AgNPs synthesized from methanolic extract had maximum absorbance at pH 8-9, at 55°C, and at 0.2 mL NaCl concentration. In UV-spectroscopy analysis, a maximum peak is observed at approximately 450 nm, which is favorable for the biosynthesis of AgNPs. Fourier transform infrared spectroscopy (FT-IR) confirmed the involvement of proteases, flavonoids, amides, and aldehydes in the reduction process of AgNPs. Scanning electron microscopy (SEM) analysis of synthesized silver nanoparticles was primarily spherical. Energy dispersive x-ray spectroscopy (EDS) analysis of methanol, ethanol, and aqueous AgNPs revealed the existence of Ag nanoparticles at 3 Kve. The insecticidal activity of AgNPs was tested against Tribolium castaneum at various concentrations (50, 100, and 200 µg.mL^-1), and the results showed superior efficacy compared to the plant extracts alone. Phytotoxic activity was also assessed at these same doses, revealing that AgNPs exhibited significantly higher phytotoxicity than the extracts. Antioxidant potential, measured through 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, indicated that AgNPs possessed greater antioxidant capacity than the plant extracts. Furthermore, biosynthesized AgNPs demonstrated potent antibacterial activity against Pseudomonas aeruginosa and strong antifungal activity against Aspergillus niger. The study concludes that AgNPs synthesized from A. lachnantha stem extracts have significant potential for use in pharmaceutical applications and commercial medicinal products.