Multitarget Antibacterial Potential of Salvia splendens –Mediated Co ₃ O ₄ Nanoparticles: Experimental and In Silico Evidence

The rapid emergence of antibiotic resistance has intensified the need for alternative antimicrobial strategies. In this study, cobalt oxide (Co 3 O 4 ) was synthesized via a green approach using Salvia splendens leaf extract as the reducing and stabilizing agent. Structural characterization techniques, including UV–visible spectroscopy, FTIR, XRD, SEM, and EDX, confirmed the formation of crystalline, spinel‐structured Co 3 O 4 with high phase purity and an optical band gap of 1.65 eV. The biosynthesized nanoparticles (NPs) demonstrated prominent antibacterial activity against both Gram‐positive and Gram‐negative bacteria. The highest antibacterial effect was observed against Staphylococcus aureus with a 47.2 mm zone of inhibition, while Escherichia coli showed a zone of 36.1 mm. MIC values were 125 μg/mL for S. aureus and 250 μg/mL for E. coli , whereas MBC values were 500 μg/mL and 1 mg/mL, respectively. Molecular docking analysis for mechanistic prediction identified potential interactions between Co 3 O 4 and E. coli target proteins, particularly DNA gyrase B (GyrB). In addition, the NPs showed dose‐dependent antioxidant activity and effective photocatalytic degradation of methylene blue dye under solar irradiation. Overall, these findings highlight the multifunctional potential of green‐synthesized Co 3 O 4 NPs as promising candidates for antimicrobial and environmental remediation applications.