Abstract
[Background] From the point of view of sustainability, economic efficiency, and throughput, in vitro toxicity tests are growing in importance. In most cases, test substances are dissolved in water. However, safety test of some substances is difficult due to their insolubility. We therefore explored novel solvents with high biocompatibility and found that Zwitterionic Ionic Liquids (ZIL) enhanced the solubility for certain food-related substances such as ellagic acid and showed lower toxicity compared to DMSO. This study aimed to find the benefits and limitations using ZIL in safety testing.
[Methods] Ellagic acid was dissolved in 1% DMSO, 1% or 2% ZIL, then treated for 24 hours on HepG2 cells at 0, 30, 100, 300, and 600 μM to measure cell viability. Drug interactions were surveyed using human liver-derived microsomes and human hepatocytes for Cytochrome P450 (CYP) inhibitory tests. Additionally, CYP induction tests on human hepatocytes and P-glycoprotein (P-gp) inhibitory tests on Caco-2 cells were conducted.
[Results] Co-treatment with ZIL alleviated ellagic acid-induced cytotoxicity and improved hazard predictivity for hepatotoxicity. ZIL expressed inhibitory effects on all CYP isozymes tested and exhibited inducing effects on all CYP isozymes tested. No P-gp inhibitory activity was observed.
[Conclusion] As a novel solvent for food-related substances, ZIL was found to be beneficial in terms of improved safety and solubility, with enhanced safety testing performance for low solubility substances. Attention to impact on metabolic activity is, however, necessary when using ZIL in tests with CYP metabolic activities.
