Green synthesis of silver nanoparticles using Achillea arabica and their antioxidant, anti-inflammatory, antidiabetic, and antimicrobial activities

Abstract Green synthesis of metallic nanoparticles using plant extracts has emerged as an environmentally friendly and sustainable alternative to conventional chemical and physical fabrication methods. In the present study, silver nanoparticles (AgNPs) were biosynthesized using aqueous extracts of Achillea arabica leaves and flowers, which served as natural reducing and stabilizing agents. The formation of nanoparticles was initially confirmed by a rapid color change of the reaction mixture and further characterized using UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). UV–Vis spectra revealed characteristic surface plasmon resonance peaks at 450 nm for leaf-derived nanoparticles (AgNPsLe) and 490 nm for flower-derived nanoparticles (AgNPsFl), confirming successful nanoparticle formation. XRD analysis indicated the crystalline nature of the nanoparticles with a face-centered cubic (fcc) silver structure, with crystallite sizes ranging from 13–20 nm. SEM micrographs revealed distinct morphological differences, where AgNPsLe predominantly exhibited cubic structures, while AgNPsFl were mainly spherical, suggesting that phytochemical composition influences nanoparticle nucleation and growth orientation. The biological activities of the extracts and synthesized nanoparticles were assessed through antioxidant, antibacterial, and antibiofilm assays. The flower extract showed the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (81.68%), whereas AgNPsLe demonstrated the strongest Ferric Reducing Antioxidant Power (FRAP) activity with a Half maximal inhibitory concentration (IC ₅₀ ) of 0.139 mg mL ^{− 1} . Antibacterial evaluation revealed that AgNPsFl exhibited the highest antimicrobial potency with Minimum Inhibitory Concentration (MIC) values ranging from 37.5–75 μg mL ^{− 1} , while AgNPsLe showed MIC values between 75 and 150 μg mL⁻ ¹ . Furthermore, the synthesized nanoparticles significantly inhibited bacterial biofilm formation with inhibition rates reaching approximately 64%.These findings highlight the potential of A. arabica -mediated AgNPs as promising bioactive nanomaterials for antimicrobial and biomedical applications, emphasizing the role of plant-derived phytochemicals in controlling nanoparticle morphology and biological activity.