Antimicrobial Activity of Biosynthesized Silver Nanoparticles from Mentha arvensis and Syzygium aromaticum and Their Combinations with Levofloxacin and Cefotaxime

Abstract

Aims: This study is aimed at evaluating the antimicrobial activity of biosynthesized silver-nanoparticles (AgNPs) from Mentha arvensis and Syzygium aromaticum and its combinations with cefotaxime and levofloxacin. Study Design: Cross sectional study. Place and Duration of Study: Biological Science Department of National Institute for Pharmaceutical Research and Development Idu Abuja, between January 2025 and August 2025. Methodology: The AgNPs were biosynthesized from Mentha arvensis (M. arvensis) and Syzygium aromaticum (S. aromaticum) extracts and characterized with Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. The antimicrobial activity of AgNPs, cefotaxime and levofloxacin against the Pseudomonas aeruginosa (P. aeruginosa) isolates (B1, B2 and B3) from surgical wound were evaluated using the microbroth dilution method. The effect of combination of the AgNPs and cefotaxime or levofloxacin was evaluated using the checkerboard method. Results: The size of S. aromaticum and M. arvensis were 50-179nm with an average of 114.5nm and 80-268nm with an average of 174nm respectively. The AgNPs biosynthesized from S. aromaticum and M. arvensis had activity against the isolates with minimum inhibitory concentrations (MICs) ranges from 6.25-0.0078 mg/mL while for cefotaxime and levofloxacin, the MICs ranges from 64.0-2.0 µg/mL. The combination of S. aromaticum/cefotaxime, S. aromaticum/levofloxacin and M. arvensis/levofloxacin had synergistic effect against only B1 with FICs ranges from 0.125-0.5 but had indifference effect on isolate B2 and B3 with FICs of 2.0. Finally, the combination of M. arvensis/cefotaxime had additive effect on B1 and B2 with FICs of 1.0. Conclusion: The biosynthesized AgNPs from S. aromaticum and M. arvensis had antipseudomonal activity with inconsistent effect in its combination with cefotaxime and levofloxacin against the P. aeruginosa isolates.