Green-synthesized silver nanoparticles from Camellia sinensis: mechanistic insights into phenolic-mediated multifunctional biological activities.

BACKGROUND: Green synthesis of silver nanoparticles (AgNPs) using plant extracts provides an eco-friendly route that bridges phytochemistry with nanobiotechnology. Camellia sinensis, rich in polyphenols, serves as an effective reducing and stabilizing agent in this process.Ethanolic extracts of C. sinensis leaves were characterized for phenolic composition by HPLC-DAD and utilized for AgNP synthesis (CS-AgNPs). The nanoparticles were characterized by UV-Vis, FTIR, XRD, SEM, EDX, and DLS. Biological properties were assessed through antioxidant (DPPH, ABTS), antibacterial (Gram-positive and Gram-negative strains), anti-inflammatory (BSA denaturation), and enzyme inhibitory (urease, α-glucosidase) assays, supported by molecular docking. RESULTS: EGCG was the dominant phenolic compound (54.8 ± 2.8 mg/g). CS-AgNPs displayed strong antioxidant (IC50: 28.78 µg/mL for DPPH), anti-inflammatory (IC50: 66.78 µg/mL), antibacterial (16.78-25.31 mm inhibition zones), and enzyme inhibitory activities (urease IC50: 20.6 µg/mL; α-glucosidase IC50: 140.9 µg/mL). Docking analysis confirmed the strong binding affinity of EGCG with target enzymes (-12.386 and -10.129 kcal/mol). CONCLUSIONS: This study highlights the dual role of C. sinensis phenolics in nanoparticle formation and bioactivity modulation, offering mechanistic insight into phenolic-metal interactions. Future work will focus on cytotoxicity and in vivo evaluations to validate the biomedical potential of CS-AgNPs.