Ecotoxicological Assessment of Two Ionic Liquids (Choline Octanoate and 1-Methyl-1-Propyl Pyrrolidinium Chloride) on the Embryonic Development of Zebrafish

Abstract

Background: Ionic liquids (ILs) are emerging as green alternatives for various industrial applications, yet concerns about their environmental impact persist. This study evaluates the acute toxicity of two ILs—choline octanoate (ChOC) and 1-methyl-1-propyl pyrrolidinium chloride (PMPY [Chloride])—using zebrafish embryos to assess mortality, teratogenicity, and organ-specific toxicity. Methods: Acute toxicity assays were conducted to determine the LC50 and NOEC of ChOC and PMPY [Chloride]. Zebrafish embryos were exposed to various concentrations of each IL, and organ-specific toxicity was assessed, including cardiotoxicity (blood flow, vessel diameter), neurotoxicity (locomotor activity), hepatotoxicity (liver size and yolk retention), and cellular stress (apoptosis via acridine orange staining). Results: ChOC exhibited substantial toxicity with an LC50 of 28.27 µM, categorizing it as "moderately toxic," while PMPY [Chloride] displayed significantly lower toxicity, with an LC50 of 796 µM, classifying it as "practically non-toxic." ChOC caused pronounced teratogenic effects, including reduced body length, yolk sac edema, and impaired hatching, alongside marked cardiotoxicity, neurotoxicity, and cellular apoptosis. In contrast, PMPY [Chloride] demonstrated minimal toxicity, with negligible impact on developmental and physiological parameters, apart from a slight increase in heart sac edema at the highest tested concentration. Conclusion: These findings emphasize the differences in toxicity profiles between the two ILs, identifying PMPY [Chloride] as a safer and more sustainable alternative. Conversely, ChOC's higher toxicity highlights the need for careful evaluation in industrial applications to minimize potential ecological risks.

Keywords: Keywords: 1-methyl-1-propyl pyrrolidinium chloride, choline octanoate, Ionic Liquids, zebrafish, eco-friendly ionic liquids, ecotoxicity.