ERA Chair of Green Chemistry, Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn 12618, Estonia; Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn 12618, Estonia; Department of Chemistry, Satya Wacana Christian University, Salatiga 50711, Indonesia.
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn 12618, Estonia.
Ecotoxicol Environ Saf. 2019 May 15;172:556-565. doi: 10.1016/j.ecoenv.2018.12.076. Epub 2019 Feb 15.
A library of 24 pyridinium-, imidazolium-, and cholinium-based ionic liquids (ILs) with varying alkyl chain from C to C was toxicologically profiled using naturally luminescent marine bacteria Vibrio fischeri. The toxicity (30-min EC) of studied ILs to Vibrio fischeri ranged from 7.82 µM (4.2 mg/L) (PyCPhe) to 3096 µM (1227 mg/L) (ImidCPhe), i.e. from "toxic" (EC 1-10 mg/L) to "not harmful" (EC > 100 mg/L). Inhibition of the bacterial luminescence upon 30-min exposure to ILs correlated well with bacterial viability (exposure for 4 h). The toxicity of studied ILs was largely driven by the length of the alkyl chain (hydrophobicity) and not the type of cationic part of the IL: starting from C all the ILs irrespective of the cationic part proved "toxic". The toxicity of the studied ILs was increasing in parallel to their hydrophobicity up to log K = 1 (C-C) and then levelling up, being consistent with the previously obtained analogous data sets. The "cut-off" effect reported in this study for longer chain length members of the ILs series leads to the "limit" toxicity level for this type of ILs to be ca. 8 mM. Two open-access online tools (www.molinspiration.com and www.vcclab.org) have been applied for the calculation of the K values for the 24 ILs reported in this study and 21 ILs reported in the literature. This lead to plotting two nonlinear monotonic correlations between the values of experimental log (1/EC) and calculated log K. The limitation of the online tools and an effect of the ILs structure on the "cut-off" effect have been discussed. The challenge of developing low microbial toxicity surface active ILs remains a significant task to overcome. Our results shed light on the new approaches for designing environmentally benign ILs and functional surfactants. As the hydrophobicity of the ILs significantly correlated with the toxicity, the Vibrio fischeri assay could be considered a powerful tool in providing toxicity data for building and evaluating the QSAR toxicity models for ILs.
我们使用具有自然发光特性的海洋细菌费氏弧菌（Vibrio fischeri）对 24 种不同烷基链长度（从 C 到 C ）的吡啶鎓、咪唑鎓和胆碱基离子液体（ILs）的文库进行了毒理学分析。研究中 ILs 对费氏弧菌的毒性（30 分钟 EC ）范围为 7.82µM（4.2mg/L）（PyCPhe）至 3096µM（1227mg/L）（ImidCPhe），即从“有毒”（EC 1-10mg/L）到“无毒”（EC>100mg/L）。在 30 分钟暴露于 ILs 后，细菌发光的抑制与细菌活力（暴露 4 小时）密切相关。研究中 ILs 的毒性主要取决于烷基链的长度（疏水性），而与 IL 的阳离子部分类型无关：从 C 开始，所有 ILs 无论阳离子部分如何，均被证明“有毒”。研究 ILs 的毒性与其疏水性平行增加，直至 log K =1（C-C），然后趋于稳定，与之前获得的类似数据集一致。本研究报告的 IL 系列中较长链长成员的“截止”效应导致此类 IL 的“极限”毒性水平约为 8mM。已应用两个开放获取的在线工具（www.molinspiration.com 和 www.vcclab.org）来计算本研究报告的 24 种 IL 和文献中报告的 21 种 IL 的 K 值。这导致了实验 log（1/EC）值和计算 log K 值之间的两个非线性单调相关的绘制。在线工具的局限性以及 IL 结构对“截止”效应的影响已进行了讨论。开发低微生物毒性表面活性剂 IL 的挑战仍然是一个需要克服的重大任务。我们的研究结果为设计环境友好型 IL 和功能表面活性剂提供了新的方法。由于 ILs 的疏水性与毒性显著相关，因此 Vibrio fischeri 测定法可被视为提供毒性数据的有力工具，可用于构建和评估 ILs 的定量构效关系毒性模型。
