Fatty acids, including medium-chain saturated and polyunsaturated fatty acids, are known for their broad health benefits, including antimicrobial activity. Through their green properties, deep eutectic systems have been heralded as having the potential to be at the forefront of pharmaceutical applications. In this work, capric acid and geranic acid, two examples of medium-chain saturated and polyunsaturated fatty acids, were employed to enhance the pharmaceutical properties and the antibacterial activity of levofloxacin. To this end, levofloxacin formulations with either capric or geranic acid were prepared and characterized using appropriate techniques. Levofloxacin was utilized to create innovative deep eutectic systems in conjunction with capric acid at three different molar ratios: 1:9, 2:8 and 3:7. This was confirmed through a rigorous analysis involving nuclear magnetic resonance, infrared spectroscopy and differential scanning calorimetry. Furthermore, it is noteworthy that geranic acid demonstrated an impressive threefold improvement in levofloxacin's solubility compared to its solubility in aqueous solutions. The antibacterial activity of the novel combinations of levofloxacin with either fatty acid was evaluated using a checkerboard titration assay. Gratifyingly, both formulations exhibited synergistic effects against a panel of levofloxacin-sensitive and resistant Gram-negative bacteria. In conclusion, the observed superior antibacterial activity of levofloxacin illuminates the potential use of fatty acid-based formulations and deep eutectic systems as green and innovative strategies to combat the global antimicrobial resistance problem.
Keywords: antibacterial activity; capric acid; deep eutectic system (DESs); geranic acid; levofloxacin.
© 2023. The Author(s), under exclusive licence to American Association of Pharmaceutical Scientists.