In vitro and in silico evidences about the inhibition of MepA efflux pump by coumarin derivatives.

The discovery of antibiotics has significantly transformed the outcomes of bacterial infections in the last decades. However, the development of antibiotic resistance mechanisms has allowed an increasing number of bacterial strains to overcome the action of antibiotics, decreasing their effectiveness against infections they were developed to treat. This study aimed to evaluate the antibacterial activity of synthetic coumarins Staphylococcus aureus in vitro and analyze their interaction with the MepA efflux pump in silico. The Minimum Inhibitory Concentration (MIC) determination showed that none of the test compounds have antibacterial activity. However, all coumarin derivatives decreased the MIC of the standard efflux inhibitor ethidium bromide, indicating antibacterial synergism. On the other hand, the C14 derivative potentiated the antibacterial activity of ciprofloxacin against the resistant strain. In silico analysis showed that C9, C11, and C13 coumarins showed the most favorable interaction with the MepA efflux pump. Nevertheless, due to the present in silico and in vitro investigation limitations, further experimental research is required to confirm the therapeutic potential of these compounds in vivo.

Chemical composition and antibacterial effects of Etlingera elatior (Jack) R.M. Smith against Staphylococcus aureus efflux pumps.

Multidrug resistance is a significant health problem worldwide, with increasing mortality rates, especially in the last few years. In this context, a consistent effort has been made to discover new antibacterial agents, and evidence points to natural products as the most promising source of bioactive compounds. This research aimed to characterize the antibacterial effect of the essential oil of Etlingera elatior (EOEE) and its major constituents against efflux pump-carrying Staphylococcus aureus strains. The essential oil was extracted from fresh inflorescences by hydrodistillation. Chemical analysis was performed using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography equipped with a flame ionization detector (GC-FID). The strains RN-4220, 1199B, IS-58, and 1199 of S. aureus were used to evaluate the antibacterial activity and the inhibition of efflux pumps. A total of 23 compounds were identified, including dodecanal and 1-dodecanol as major compounds. EOEE and dodecanal showed weak activity against the strains, while 1-dodecanol inhibited bacterial growth at low concentrations, indicating strong antibacterial activity. In addition, this compound potentiated the activity of norfloxacin against S. aureus 1199. In conclusion, 1-dodecanol was identified as the most effective compound of EOEE, showing significant potential to be used in antibacterial drug development.