In vivo and in vitro toxicity profile of tetrabutylammonium bromide and alcohol-based deep eutectic solvents

Deep eutectic solvents (DESs) have emerged as new promising solvents in the field of "green chemistry," which possess a broad range of potential applications. However, the ecotoxicological profile of these solvents is still poorly known. In this study, ammonium-based deep eutectic solutions with glycerol (2:2), ethylene glycol (1:2), and diethylene glycol (1:2) as hydrogen bond donors in 1:2 proportion were evaluated for their interaction with various biological systems, including gram-positive and negative bacteria, fungi, fish, and human fibroblast cell lines. The DES synthesis was confirmed by Fourier transform infrared spectroscopy analysis, which analyses the interactions between DES precursors for their synthesis. The antimicrobial activity of tetrabutylammonium bromide: ethylene glycol was the most potent, while tetrabutylammonium bromide: diethylene glycol had a higher LC50 against C. carpio fish. Tetrabutylammonium bromide: glycerol was supposed to be the most suitable DES in terms of cell viability percentage (118%) and 2,2-diphenyl-1-picrylhydrazyl scavenging activity (93%). Finally, tetrabutylammonium bromide in glycerol can be considered an eco-friendly solvent due to its lower toxicity in both in vivo and in vitro environments.