<i>In vivo</i> and in silico efficacy of biosynthesized <i>camellia</i> sinensis mediated gold nano particles in reversing stress-induced physiological dysregulation

In recent years, sustainable and eco-friendly approaches for synthesizing metallic nanoparticles have attracted considerable attention due to their reduced toxicity and environmental compatibility. In this study, we developed a green synthesis method to produce gold nanoparticles (AuNPs) using Camellia sinensis ( C. sinensis ) extract as a natural stabilizing and reducing agent. This approach enabled the formation of core–shell nanoparticles with enhanced stability, predominantly spherical morphology, and minimal size variation, alongside small pentagonal, triangular, and hexagonal shapes. The biosynthesized C. sinensis -AuNPs were comprehensively characterized using UV–visible spectroscopy, high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and zeta potential analysis, confirming their structural integrity and physicochemical properties. To explore their therapeutic potential, we evaluated the anti-stress efficacy of both C. sinensis extract and its AuNP formulation in rats subjected to a resident–intruder stress model. Animals received 25 or 50 mg/kg of either the extract or nanoparticles as their sole fluid intake for eight days. Stress exposure significantly increased body and adrenal gland weights and elevated stress-related hormone levels compared to controls (p &lt; 0.05). Treatment with C. sinensis , its AuNP formulation, or diazepam markedly mitigated these stress-induced changes, with the 50 mg/kg nanoparticle dose showing the most pronounced effect, restoring parameters nearly to baseline. Additionally, ADMET profiling and molecular docking highlighted the promising therapeutic potential of key bioactive components. Collectively, these findings demonstrate that plant-based extracts and green-synthesized nanoparticles can offer enhanced protection against stress-induced physiological dysfunctions, presenting a sustainable and natural alternative to conventional pharmaceutical therapies. GRAPHICAL ABSTRACT