Green Synthesis and Bioactivities of Silver Nanoparticles Derived from Mercurialis annua L. Extract

Biogenic synthesis using plant materials provides a sustainable alternative to classical nanoparticle fabrication, minimizing chemical hazards and decreasing energy input. In this study, silver nanoparticles (AgNPs) were prepared using an aqueous extract of Mercurialis annua and characterized. Physicochemical properties of the AgNPs were confirmed using ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD), and transmission electron microscopy coupled with energy-dispersive X-ray (TEM–EDX), which collectively indicated crystalline, spherical silver nanoparticles stabilized by extract-derived functional groups. Subsequently, the biological activities of both the nanoparticles and the extract were comparatively evaluated using antioxidant tests, including cupric ion reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic content (TPC), and total flavonoid content (TFC), as well as enzyme inhibition tests targeting α-glucosidase and carbonic anhydrase. Liquid chromatography-mass spectrometry profiling identified 31 phenolic constituents in the extract, with ferulic, caffeic, salicylic, and 4-hydroxybenzoic acids detected in high abundance. Overall, the biosynthesized AgNPs demonstrated higher antioxidant performance and stronger inhibitory effects on both enzymes compared with the crude extract. These results indicate that M. annua-based AgNPs hold considerable promise sustainable and effective bioactive agents for future biomedical and biotechnological applications.