Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 3 2026 06 07 345 356 Abdolrazagh Marzban Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran Pegah Shakib Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran Seyedeh Zahra Mirzaei Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran Gholamreza Goudarzi Department of Microbiology, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran Fatemeh Jahani Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran 2025 06 10 2026 05 13 Background and Objectives: Following the emergence of microbial resistance to chemical antimicrobial agents, researchers have recently focused on the effects of nanoparticles and their antimicrobial activity. This research aimed to investigate the antimicrobial and antioxidant activity of copper oxide nanoparticles (CuO-NPs) produced using the hydroalcoholic extract of Salvia officinalis (S. officinalis). Materials and Methods: In this study, after preparing the hydroalcoholic extract of S. officinalis and synthesizing CuO-NPs using this extract, the synthesized nanoparticles were evaluated. The antimicrobial properties of synthesized CuO-NPs were investigated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the microbroth dilution method. The minimum biofilm inhibitory concentration (MBIC) and antioxidant activity of CuO-NPs and the hydroalcoholic extract of S. officinalis against Pseudomonas aeruginosa (P. aeruginosa) were investigated. Results: CuO-NPs have a size in the range of 40 nm and a monoclinic crystal structure. Antimicrobial activity assessment by well diffusion showed that the synthesized CuO-NP nanoparticles at concentrations below 5 mg/mL had no antimicrobial effect on any of the bacteria studied. The lowest MIC of the synthesized CuO-NPs was observed against Staphylococcus saprophyticus (S. saprophyticus), and the highest against P. aeruginosa and Bacillus cereus (B. cereus). On the other hand, the highest MBC was related to B. cereus. The plant extract exhibited much weaker antimicrobial activity than CuO-NPs. The results obtained showed that the MBIC for CuO-NPs was 312 μg/mL. The half-maximal inhibitory concentration (IC50) obtained from CuO-NPs and the hydroalcoholic extract of S. officinalis was 2.79 and 1.97mg/ml, respectively. Conclusion: Based on the results of this study, the green synthesis of CuO-NPs using hydroalcoholic extract of S. officinalis is a suitable candidate for the preparation of antimicrobial and antibiofilm compounds that also have antioxidant properties. https://ijm.tums.ac.ir/index.php/ijm/article/view/5566 https://ijm.tums.ac.ir/index.php/ijm/article/download/5566/1894