Green Synthesis of Silver Nanoparticles Using Grewia tiliaefolia Vahl Leaf Extract: Characterisation, Process Optimisation and Hepatoprotective Activity Against Paracetamol-Induced Liver Toxicity in Rats.

Introduction: Scientists around the world are focusing on 'green,' environmentfriendly, and cost-effective green synthesis of nanometals using various plant extracts to combat various ailments. Among nanometals, Silver (Ag) is one of the most commercialised nanomaterials due to its wide applications in biotechnology and biomedical fields. The present study reports the first facile synthesis, characterization, and process optimisation of Ag nanoparticles (NPs) using aqueous Grewia tiliaefolia leaf extract (Gt) as a reducing and surface functionalising agent.

Methods: Characterisation of Gt-mediated Ag-NPs was performed using FTIR. The morphology and microstructures of Gt-derived Ag-NPs were analysed using TEM and FE-SEM. In vitro, antioxidant activity was evaluated against DPPH radicals, hydrogen peroxide radicals, and ferric ions. In vitro, anticancer activity was assessed on MCF-7 and HepG2 cell lines. In vivo, hepatoprotective activity was tested against paracetamol-induced liver toxicity in rats.

Results: FTIR analysis confirmed the interaction between Ag-NPs and Gt. The optimal conditions for Gt-derived Ag-NPs were found to be 4 mM AgNO3, 5% Gt, at 90°C for 60 minutes, at pH 9. UV-Visible spectroscopy, XRD, FE-SEM, and TEM revealed the phase formation, spherical morphology, and surface functionalisation of Gt-derived Ag-NPs, which were stable (-28.3 mV) with an average particle size of 14.5±0.05 nm. The Gt-derived Ag-NPs were found to be highly effective in significantly inhibiting DPPH radical, ferric ions, and hydroxyl radicals. Additionally, the cytotoxicity of Gt-derived Ag-NPs was more effective against MCF-7 cells compared to HepG2 cells. They also exhibited dose-dependent protection against hepatoprotective activity in albino rats.

Discussion: The hepatoprotective effects of Gt-mediated Ag-NPs likely result from the combined action of bioactive phytochemicals (such as α/β-amyrin, γ-lactones, betulin, and lupeol), and their ability to scavenge ROS, reduce oxidative stress, and modulate inflammatory pathways. These mechanisms, supported by reduced lipid peroxidation and increased antioxidant activity in paracetamol-induced hepatotoxicity, suggest their therapeutic potential in liver protection and regeneration.

Conclusion: Overall, Gt proves to be an eco-friendly and non-toxic source for synthesizing bioactive Ag-NPs at optimal conditions.