Eco-friendly synthesis of silver nanoparticles from Woodfordia fruticosa flower extract: Exploring their biological applications

The impending issue of microbial antibiotic resistance concerns global health, emphasizing the need for effective preventative and therapeutic strategies. Silver nanoparticles have gained considerable attention for their unique properties and ability to inhibit drug-resistant bacteria. Biogenic silver nanoparticles (AgNPs) synthesized from natural extracts offer a cost-effective and environmentally friendly method, reducing environmental impact while maintaining potent therapeutic efficacy. Thus, the current study investigated the antibacterial activity and oxidative stress-mediated mechanistic insights of AgNPs synthesized from Woodfordia fruticosa (Wf) flower extract on Gram-positive Staphylococcus chromogenes and Gram-negative Pseudomonas aeruginosa . Characterization of Wf-AgNPs revealed characteristic UV–vis absorption peaks at 430 nm, a hydrodynamic size of 86.7 nm, and a zeta potential of −20 mV; XRD and transmission electron microscopy confirmed crystalline structure and multiple morphologies, respectively. Fourier-transform infrared spectrum analysis revealed phenolic and amine groups on the Wf-AgNPs surface. Antibacterial properties were evaluated through antimicrobial susceptibility tests and the determination of minimal inhibitory concentration. Further, oxidative stress was induced in bacterial cells as evidenced by increased lipid peroxidation and protein oxidation; decreased antioxidant enzyme activity of catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST), as well as reduced glutathione (GSH) levels. Cytotoxic effects on human lung adenocarcinoma (A549) cells were evaluated using MTT, ROS detection, and Hoechst staining assays. The results showed a dose-dependent decrease in cell viability, increased ROS levels, and DNA damage. Overall, the results showed that the Wf-AgNPs have potential antimicrobial activity against Gram-positive and Gram-negative bacteria as well as cytotoxic activity against A549 cells.