Dual Functionality of <i>Argyreia speciosa</i> ‐Mediated Silver Nanoparticles: Insights Into Oxidative Stress Mechanisms, Antimicrobial and Anticancer Activity

ABSTRACT Silver nanoparticles (AgNPs) are promising therapeutic agents against multidrug‐resistant (MDR) bacterial infections and cancer. The biogenic AgNPs were synthesized from Argyreia speciosa ( As) leaf extract and characterized using UV–vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM)‐energy‐dispersive x‐ray spectroscopy (EDX), x‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR). The synthesized As‐AgNPs had a spherical shape, a crystalline morphology, showed a surface plasma resonance (SPR) peak at 440 nm, a hydrodynamic size of 61.8 nm, and a zeta potential of −24.7 mV. As‐AgNPs demonstrated potent antibacterial activity against MDR strains, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis , and Staphylococcus aureus , exhibiting significantly greater zones of inhibition (16–18 mm) than AgNO 3 . Increased lipid and protein oxidation, decreased activity of catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH) levels in bacterial cells at concentrations of 0.32, 0.64, and 1.28 µg/mL, as compared to the control, suggest that As‐AgNP induces oxidative stress. Anticancer activity was evaluated by assessing cytotoxicity, ROS levels, apoptosis, and cytokine release in A549 cells. As‐AgNP significantly increased cytotoxicity (IC 50 1.99 µg/mL) and ROS. Increased sub G0/G1 cell population and BAX/BCL2 ratio in As‐AgNP‐treated cells indicated apoptotic cell death. Further, As‐AgNP at sublethal concentrations modulated inflammatory cytokine levels. Overall, in vitro bactericidal and cytotoxic results support As‐AgNP as a potential antimicrobial and anticancerous agents, thereby paving the way for further in vivo investigations.