Optimized Catha edulis leaf extract mediated synthesis of silver nanoparticles and their antibacterial activity against selected pathogenic bacteria

Abstract

Green synthesis of metal nanoparticles using plant-derived extracts has emerged as a sustainable alternative to conventional chemical and physical methods. In this work, silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Catha edulis as a reducing and stabilizing agent. The formation of AgNPs was confirmed by the characteristic color change of the reaction mixture and the appearance of a distinct surface plasmon resonance (SPR) band at 416 nm in the UV–Vis spectrum. Structural characterization by X-ray diffraction revealed diffraction peaks at 2θ values of 38.23°, 44.34°, 64.52°, and 77.39°, corresponding to the (111), (200), (220), and (311) planes of face-centered cubic silver, confirming crystallinity. Fourier transform infrared analysis indicated the involvement of phytochemicals, including flavonoids, phenolics, alkaloids, and tannins, in nanoparticle formation and stabilization. The biosynthesized AgNPs exhibited measurable antibacterial activity against K. pneumoniae and S. pyogenes, producing a zone of inhibition (ZOI) of 21.20 ± 0.78 mm and 18.63 ± 0.53 mm respectively. These findings highlight the potential of Catha edulis extract for the eco-friendly synthesis of functional AgNPs with promising biomedical applications.