Evaluation of the inhibitory effect of isopulegol (ISO) and its β-cyclodextrin inclusion complex (ISO/β-CD) on the reversal of Staphylococcus aureus efflux pump activity

Staphylococcus aureus is known to be a human pathogen and is often resistant to antibiotics, so there is a demand for new treatment alternatives that have the ability to reverse such resistance. The present study aimed to evaluate the antibacterial action and reversal of the efflux pump activity of the compounds Isopulegol (ISO) and its β-cyclodextrin inclusion complex (ISO/β-CD) in S. aureus strains carrying an efflux pump. (MsrA, TetK, NorA and MepA). The complex was obtained using the paste complexation method. The minimum inhibitory concentration (MIC) of ISO and ISO/β-CD was determined for the evaluation of antibacterial activity against multiresistant strains of S. aureus (RN4220, IS-58, 1199, 1199B and K2068) and the compounds showed a minimum inhibitory concentration (MIC) ≥ 1024 μg/mL. Modulation assays were performed using ISO and ISO/β-CD, which associated with antibiotics and Ethidium Bromide (EtBr) showed synergism and MIC reduction in some of the tested bacteria. Therefore, it can be concluded that the isolated compounds ISO and ISO/β-CD are effective in inhibiting the efflux pump mechanism against some of the tested strains; with modulation, only strains IS-58, SA 1199 and K2068 showed a MIC decrease effect, while all strains showed a reduction in MIC with ethidium bromide.