Functionalized imidazolium-based ionic liquids: biological activity evaluation, toxicity screening, spectroscopic, and molecular docking studies

A series of long-chain imidazolium-based ionic liquids (ILs) 1-dodecyl-3-methylimidazolium chloride ( 1 ), 1,3-bis(octyloxycarbonylmethyl)imidazolium chloride ( 2 ) and 1-dodecyloxycarbonylmethyl-3-methyloxycarbonylmethylimidazolium chloride ( 3 ), were synthesized and evaluated as antimicrobials against a wide range of bacteria and fungi. Toxicological risks of selected compounds were assessed using the biomodels of various organizational and functional levels. All compounds demonstrated significant antibacterial and antifungal activity. The toxicity results indicate that ILs containing an ester functional group in the alkyl side chain exhibited much lower toxicity to D. magna and acetylcholinesterase inhibition than ILs with long alkyl chain without polar substituents, while toxicity toward Danio rerio was on a par. The HSA-binding properties of ILs have been investigated by FT-IR spectroscopy technique and the evidences have suggested that the test compounds could induce the protein unfolding and changes in the secondary structure of HSA. The docking studies were carried out to provide structural insights of the ILs–HSA-binding interactions. The docked compounds exhibit a high binding affinity to HSA and the hydrogen bonding, hydrophobic and electrostatic interactions played a major role in the process. ILs 2 and 3 may be perspective for further investigation as potential low-toxic biocides with high antimicrobial activity against reference and clinical multidrug-resistant strains.