Evaluation of the Antimicrobial Property of Combined Fractionated Extract of Peppermint Leaves with Eucalyptus Oil

Abstract

Antimicrobial resistance (AMR) poses a significant global challenge, impacting both public health and economies worldwide. Efforts to address this issue have focused on developing innovative solutions within the limitations of existing medications, such as combining different drugs to combat it more effectively. This study investigated the combined antimicrobial effects of peppermint and eucalyptus oil extracts on three harmful bacterial strains: Escherichia coli (ATCC25923), Pseudomonas aeruginosa (ATCC27853), and Staphylococcus aureus (ATCC28213).

The researchers extracted aerial components from Mentha piperita using ethanol and further separated them into fractions with hexane, ethyl acetate, and water. These fractions were then combined in various ratios and tested for antimicrobial activity using Kirby Bauer Disk Diffusion Assay and MIC by microbroth dilution technique. The results showed that combinations of the ethyl acetate fraction effectively inhibited E. coli growth, particularly at a 1:1 ratio. Other combinations did not meet susceptibility criteria outlined in CLSI guidelines. Ethyl acetate fractions in the 1:1 and 1:3 combinations showed synergistic effects according to CI analysis against E. coli and S. aureus, respectively. The study concluded that combining Mentha piperita and Eucalyptus globulus extracts as antibacterial agents did not enhance the bioactive compound’s efficacy. And it exhibited antagonism, necessitating further investigation into their in vitro activities.