Silver Nanoparticles from Stryphnodendron adstringens : A Green Synthesis Approach, Characterization, and Their Impact on Bacterial Metabolism

Abstract

This study reports the green synthesis of silver nanoparticles (AgNP@SA) using an extract from the medicinal plant Stryphnodendron adstringens as both the reducing and stabilizing agent. The resulting nanoparticles were spherical, with an average diameter of 12 ± 2 nm, and exhibited high colloidal stability, as indicated by a zeta potential of −28 ± 6 mV. Their formation and physicochemical properties were confirmed by UV–vis, TEM, EDS, STEM, DLS, XPS, FT-IR, UHPLC-HRMS/MS, and 1H-NMR analyses. Spectroscopic data showed that tannins and other phenolic compounds in the plant extract were primarily responsible for the reduction of Ag+ ions and stabilization of the nanoparticles, pointing to the involvement of related flavonoid derivatives. UHPLC-HRMS/MS analysis, interpreted through the GNPS database, further demonstrated the absence of epigallocatechin in the final nanoparticle system, supporting its proposed role as the reducing agent during nanoparticle synthesis. Biological assays demonstrated that AgNP@SA exhibited broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria. 1H-NMR-based metabolomic profiling of Staphylococcus aureus under AgNP@SA stress revealed significant metabolic disruption, including decreased levels of leucine and valine and increased levels of lysine, acetate, and betaine, suggesting the induction of cellular stress and impairment of essential metabolic pathways. Overall, these findings highlight the potential of green-synthesized AgNP@SA as effective antimicrobial agents and reinforce the value of plant-mediated nanoparticle synthesis for biomedical applications.