Propolis Extract: A Potent Bacteria Efflux Pump Inhibitor

Abstract

The research and development of specific, potent efflux pump inhibitors (EPIs) appears to be an important goal for the improved control of infectious diseases. In recent years, different classes of EPIs have been described and tested however, several of them causes side effects. Therefore, there is an increased need to search for new inhibitors. There have been no natural EPIs identified so far, so the natural bee product, propolis, that has attracted much attention in recent years for their biological and antimicrobial activities seems to be efficient for this purpose. The agar microdilution method, minimum inhibitory concentration (MIC) was implemented to evaluate the antibacterial activity of ethanolic extract of propolis (EEP) against various reference strains and against bacteria with efflux pumps and resistant microbes at concentrations ranged between 0.06 mg/ml to 8 mg/ml. Strong antibacterial activity was detected against Gram positive bacteria and Gram negative with an average MIC of 0.25 mg/ml. The combination of EEP with standard inhibitors of pumps efflux (EPIs) was more efficient against Escherichia coli and other strains with efflux pump. The present findings revealed that propolis extract inhibit the efflux pumps and so must be a promising source of new antimicrobial agents.