Green synthesis of silver nanoparticles using Viola odorata and Onosma hispidum: Evaluation of their antimicrobial, antioxidant, and hemolytic properties against multidrug-resistant microbes

Rapid increase in antimicrobial resistance poses a significant threat to global health, necessitating alternative strategies to combat multi-drug resistant (MDR) pathogens. Advances in nanobiotechnology may offer promising solutions to this pressing issue. This study revolves around developing an efficient method for synthesizing silver nanoparticles (AgNPs) based on aqueous extracts of Viola odorata leaves (VoL) and Onosma hispidum root barks (OhRb), traditional medicinal perennial herbs, followed by evaluating their antioxidant and antimicrobial potential against MDR pathogens. The synthesis of nanoparticles was completed in 15–20 min at 55–60°C using green approach. The characterized AgNPs showed significant antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae , Staphylococcus aureus, Streptococcus agalactiae , and Candida albicans , with zones of inhibition ranging from 12 mm ± 0.636 to 25 mm ± 0.282. Minimum inhibitory concentration and minimum bactericidal concentrations ranged from 0.39 to 6.125 µg/mL. Additionally, the nanoparticles demonstrated significant antioxidant potential compared to the aqueous plant extracts. Importantly, the investigation into the effects of the nanoparticles on red blood cells revealed no pronounced hemolysis even at higher concentrations (300 µg/mL) of VoL-AgNPs and OhRb-AgNPs, demonstrating their biocompatibility and hemolytic safety profile. The VoL-AgNPs and OhRb-AgNPs exhibit appreciable antimicrobial and antioxidant activities with minimal hemolysis, underscoring their potential to combat MDR pathogens, and further applicability in therapeutic settings. However, in vivo studies are warranted to explore their biomedical applications, such as in wound dressings and treatments for disorders caused by free radical damage. How to cite: Andleeb A, Khalid A, Khalil S, et al. Green synthesis of silver nanoparticles using Viola odorata and Onosma hispidum : Evaluation of their antimicrobial, antioxidant, and hemolytic properties against multidrug resistant microbes. Electron J Biotechnol 2025;74. https://doi.org/10.1016/j.ejbt.2024.12.003 .