Marrubium vulgare Leaf Extract-Assisted Green Synthesis of Silver Nanoparticles: Optimization, Characterization and In Vitro Exploration of Their Antimicrobial, Antioxidant and Anti- Inflammatory Potential

Background: Biogenic metal nanoparticles are gaining popularity due to their remarkable biomedical properties, which provide hope in the fight against various diseases. Objective: This research produced silver nanoparticles (AgNPs) from an aqueous extract of Marrubium vulgare leaves by a simple, onestep, bottom-up green route. For the first time in the literature, the antimicrobial, antioxidant, and antiinflammatory potentials of AgNPs obtained using leaves of Marrubium vulgare are investigated. Methods and results: The optimal conditions for biosynthesis were 80 °C reaction temperature, 60 min incubation time, 2 mM AgNO₃, and 100 μL extract volume. The FTIR results indicated that the distinct functional groups found in M. vulgare extract were also present in AgNPs, confirming their critical role in silver bioreduction and AgNP capping. The biosynthesized AgNPs were crystalline, with face-centered cubic geometry, according to XRD analysis. DLS analysis asserted that the constructed AgNP's average size was 34.58 nm, whereas SEM/TEM revealed their spherical morphology. The AgNPs produced through biosynthesis inhibited microbial proliferation in a dose-dependent manner. They exhibited bactericidal attributes against both Gram-negative and Gram-positive bacteria, with MIC values ranging from 0.041 to 5.312 μg/mL and MBCs from 0.083 to 5.312 μg/mL. Furthermore, the AgNPs exhibited fungicidal activity against three Candida albicans strains, with MIC and MFC respective values recorded at 2.656 and 2.656-5.312 μg/mL. Additionally, the biosynthesized AgNPs demonstrated significant antioxidant potency compared to ascorbic acid and the extract. Their potent in vitro anti-inflammatory effect, attributed to the inhibition of BSA denaturation, was directly proportional to the AgNP concentration, with a maximum inhibition of 86.14% observed at 200 μg/mL. Conclusion: Therefore, the findings suggest that AgNPs have promising applications in combating the growing threat of antimicrobial resistance and might be utilized as potent antioxidant and anti-inflammatory agents.