en فارماكوگنوزی و فارماسيوتيكس Pharmacognosy & Pharmaceutics پژوهشی Research <div style="text-align: justify;"><b><span lang="EN-GB" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Background</span></span><span lang="VI" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">:</span></span></b> <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Nanoparticle applications are expanding across biomedical research. Plant extract&ndash;mediated (green) synthesis offers a sustainable and economically viable route for nanoparticle production.<b> Objective:</b> This study</span></span> <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">focused on the synthesis of gold nanoparticles (</span></span><span lang="EN-GB" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Au</span></span><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">NPs) using </span></span><i><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Zataria multiflora</span></span></i> <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Boiss extract</span></span> <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">and evaluated their antibacterial efficacy. <b>Methods: </b></span></span><span lang="EN-GB" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Au</span></span><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">NPs were synthesized using the aqueous extract of the <i>Z. multiflora</i> plant. The nanoparticles were characterized by UV&ndash;Vis spectroscopy, energy-dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta-potential measurements. The total phenolic content of the <i>Z. multiflora</i> extract was quantified using a gallic acid standard curve. Flavonoid content was measured using quercetin as the standard. Antioxidant capacity was assessed with ascorbic acid as the reference standard. The antibacterial activity of the synthesized AuNPs was evaluated by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and by disk diffusion assays. <b>Results:</b> Spectroscopy showed a peak for </span></span><span lang="EN-GB" style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Au</span></span><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">NPs at 530 nm. DLS revealed an average hydrodynamic diameter of 123.8 nm with a moderate size distribution. The zeta-potential was highly negative (-77.7 mV), indicating colloidal stability. AuNPs exhibited significant antibacterial activity against both <i>S. aureus</i> and <i>E. coli</i> in MIC, MBC, and disk diffusion assays. <b>Conclusion: </b><i>Z. multiflora</i> extract effectively mediates the biosynthesis of stable AuNPs with notable antibacterial activity, supporting its potential for green nanomaterial synthesis in antimicrobial applications.</span></span></div> Biological synthesis, Gold nanoparticles, Antimicrobial activity, Zataria multiflora, Flavonoids, Phenols, Plant extracts 22 36 http://jmp.ir/browse.php?a_code=A-10-1658-2&slc_lang=en&sid=1 Fariba Mahmoudi faribamahmoodi71@yahoo.com 100319475328460049511 100319475328460049511 No Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Parichehr Hanachi p.hanachi@alzahra.ac.ir 100319475328460049512 100319475328460049512 Yes Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Reza Falak falak.r@iums.ac.ir 100319475328460049513 100319475328460049513 No Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Ali Mohammadi a.mohammadi@alzahra.ac.ir 100319475328460049514 100319475328460049514 No Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran