Evaluation of antimicrobial activity of gold nanoparticles biosynthesized by Scrophularia striata extract against Gram positive and Gram-negative bacteria

The increasing prevalence of antibiotic-resistant bacterial infections has prompted the search for alternative antimicrobial agents. In this study, gold nanoparticles (AuNPs) were synthesized via a green approach using aqueous extract of Scrophularia striata, a medicinal plant rich in bioactive compounds. The formation of AuNPs was confirmed by FT-IR, FE-SEM, EDX, and elemental mapping, indicating the presence of uniformly distributed, spherical nanoparticles with an average size of ~۳۰ nm. The functional groups from the plant extract played a crucial role in both reduction and stabilization of the nanoparticles. The antibacterial activity of the synthesized AuNPs was evaluated against four pathogenic bacterial strains: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Disc diffusion assays revealed inhibition zones ranging from ۱۰ to ۲۴ mm, with P. aeruginosa being the most susceptible. MIC and MBC values further confirmed potent bacteriostatic and bactericidal effects, particularly against Gram-negative strains. The plant extract alone exhibited limited antimicrobial activity, indicating a synergistic enhancement following nanoparticle synthesis. These findings demonstrate the potential of S. striata-mediated AuNPs as effective and eco-friendly antimicrobial agents, suitable for future biomedical applications in combating resistant infections.

کلیدواژه ها:

Gold nanoparticles ، Scrophularia striata ، Green synthesis ، Antibacterial activity ، MIC ، Multidrug-resistant bacteria