Green synthesis of Bupleurum rotundifolium – Silver nanoparticles: Characterization, biological activities, and preliminary environmental risk assessment

Green synthesis of silver nanoparticles (AgNPs) has gained significant attention due to its eco-friendly, cost-effective, and biocompatible nature. In this study, we report the first successful synthesis of AgNPs using the aqueous extract of aerial parts of Bupleurum rotundifolium a medicinal plant traditionally used for treating ulcers and digestive disorders. The formation of Bupleurum rotundifolium-capped AgNPs (BR@AgNPs) was validated through a visible shift in color from yellow to reddish-brown and the observation of a plasmon resonance peak at 430 nm. Comprehensive characterization using UV-Vis, FTIR, XRD, DLS, TEM, FESEM, and EDX revealed spherical nanoparticles with a crystallite size of 11.89 nm (XRD), a core diameter of 13 nm (TEM), a hydrodynamic size of 150 nm, and a zeta potential of −25 mV, indicating good stability. Phytochemicals such as flavonoids and saponins were identified as key reducing and capping agents. BR@AgNPs exhibited strong antioxidant activity with an IC 50 of 35.23 µg/mL in the DPPH assay. They also showed significant anticancer effects against AGS (IC 50 = 13.87 µg/mL, SI = 22), PC-3 (IC 50 = 16.45 µg/mL, SI = 20), and MCF-7(IC 50 =136.82 µg/mL, SI=2.3) cell lines, with potencies comparable to the standard drug doxorubicin. Furthermore, BR@AgNPs demonstrated antibacterial activity against Staphylococcus aureus , Escherichia coli , and Bacillus cereus , with MIC values as low as 15.125 µg/mL, approaching those of penicillin and streptomycin. Given their small size (≈13 nm), stability (−25 mV), and selective anticancer activity, BR@AgNPs represent a promising candidate for pharmaceutical, clinical, and food-related applications. The green synthesis approach presented is simple, scalable, and environmentally benign. • The first report of green synthesis of AgNPs using Bupleurum rotundifolium and their anticancer and antioxidant activity. • The nanoparticles displayed uniform spherical morphology (13 nm via TEM). • Results highlight the potential of BR@AgNPs as selective anticancer agents, particularly for gastric and prostate cancers. • BR@AgNPs may serve as natural alternatives to synthetic antioxidants such as BHA, which have raised safety concerns.