A zwitterionic solvent for in vitro toxicity tests of insoluble compounds

OE₂imC₃C, a zwitterionic liquid, has attracted considerable attention as an emerging solvent with low toxicity. However, the safety data in research reports are limited, and its applicability to toxicity tests remains unclear. Therefore, we investigated the detailed safety profile of OE₂imC₃C and found that it was negative in both the bacterial reverse mutation and chromosome aberration tests, indicating no concern for genotoxicity. The hepatocellular toxicity of OE₂imC₃C stock solution (OS) was lower than that of dimethyl sulfoxide (DMSO). OS was widely applied and gave correct hepatocellular toxicity of ellagic acid (a functional food molecule with anticancer, antioxidant, and other properties), based on the high solubility. In contrast, DMSO revealed false toxicity in the test because the undissolved ellagic acid crystals damaged the cells. The general applicability of OS to food-related compounds was confirmed using Hansen solubility parameters. OS is a unique solvent capable to prevent artifacts in toxicity assays involving poorly soluble compounds such as food and drug molecules.