Green synthesis of silver nanoparticles from Buddleja asiatica L. and their multifunctional applications for industrial and bio-based products.

Nanotechnology provides innovative solutions to biomedical and agricultural challenges, and silver nanoparticles (AgNPs) are of particular interest due to their broad-spectrum bioactivity. This study aimed to green-synthesize AgNPs using Buddleja asiatica leaf extract, characterize the nanoparticles, and evaluate antibacterial, antioxidant, anticancer, and phytotoxic/phytostimulatory activities. AgNP formation was confirmed by UV-visible spectroscopy (SPR peak at 420 nm). XRD verified a crystalline face-centered cubic structure, while SEM showed predominantly near-spherical nanoparticles (10-22 nm). FTIR indicated plant-derived functional groups involved in stabilization. Biologically, BA-AgNPs exhibited strong antibacterial activity against a Gram-positive clinical isolate (Streptococcus sp.) and Gram-negative bacteria, with the largest inhibition zone of 14 ± 0.57 mm at 0.9 mg/mL. Antioxidant activity reached 88.12% DPPH scavenging at 100 ppm, compared with 80.90% for ascorbic acid under the same assay conditions. BA-AgNPs showed concentration-dependent cytotoxicity in RD cells, with cell death ranging from 87.00% at 100 mg/mL to 5.33% at 0.39062 mg/mL; however, IC50 is reported only as an estimated range of 6.25-12.5 mg/mL based on the concentration interval where cytotoxicity crossed 50%. In wheat, lower concentrations showed phytostimulatory trends, with the strongest response at 50 mg/L, while 1000 mg/L caused inhibitory effects. This is the first comprehensive report on B. asiatica-mediated AgNP synthesis and multifunctional bioactivity, highlighting BA-AgNPs as a sustainable nanomaterial for antimicrobial, antioxidant, anticancer, and agricultural applications, while emphasizing the need for future stability, mechanistic, and translational safety studies.