The Antimicrobial Effects of the Combination of Mentha pulegium and Sophora alopecuroides Extracts on Some Pathogenic Bacteria

Introduction: The increasing resistance of bacteria to antibiotics is a serious public health challenge, underscoring the need for natural compounds with antimicrobial properties. This research investigated the antimicrobial effects of the hydroalcoholic extract of Mentha pulegium and the aqueous extract of Sophora alopecuroides seeds, both individually and in combination, on Escherichia coli (ATCC ۲۵۹۲۲), E. coli K-۱۲ (ATCC ۱۰۷۹۸), Staphylococcus aureus (ATCC ۲۵۹۲۳), and methicillin-resistant S. aureus (MRSA: PTCC ۱۷۶۴). Methods: Extraction was performed using the maceration method, and antibacterial tests, including well-diffusion, disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC), were conducted according to CLSI guidelines. Eventually, the fractional inhibitory concentration (FIC) index was measured for the combinations of M. pulegium with ۱/۲ and ۱/۴ MIC of S. alopecuroides for each isolate. Results: The results indicated that both extracts independently exhibited antibacterial activity, and their combination significantly reduced MIC and MBC values (by more than ۱۰-fold in some strains). In addition, the FIC index of less than ۰.۵ for all combinations of extracts in all strains indicated strong synergy between the two extracts. This synergistic effect was more pronounced in resistant strains, particularly MRSA. Conclusion: The findings revealed that the combination of M. pulegium and S. alopecuroides extracts can be considered an effective natural option for controlling antibiotic-resistant infections and developing pharmaceutical and food products. Thus, it is recommended that further molecular-level studies, toxicological assessments, and animal/human trials be conducted for clinical applications.