Active pharmaceutical ingredients based on salicylate ionic liquids: insights into the evaluation of pharmaceutical profiles

This work is based on the evaluation of the protein binding affinity, partition coefficients (with a biomimetic membrane) and surfactant properties of three pharmaceutically active ionic liquids based on the salicylate anion. Fluorescence spectroscopy was used for the evaluation of the binding of ionic liquids to human serum albumin and for the determination of critical micelle concentrations. Partition coefficients were determined using micelles of hexadecylphosphocholine and UV-Vis derivative spectroscopy. The results indicate that all the compounds bind strongly and spontaneously to human serum albumin and exhibit the ability to form micelles. The determined partition coefficients were up to 6 times higher than those of the starting materials, evidencing that the ionic liquid form has greater affinity for the lipid phase than the inorganic salt form of salicylate. Generally, the studied salicylate ionic liquids exhibit an interesting pharmaceutical profile presenting favorable properties regarding the incorporation of the compounds in antimicrobial pharmaceutical formulations. It was evidenced that the tested ionic liquids can exert direct effects on cell membranes as indicated by their surfactant properties and high ability to partition to hydrophobic environments.