Toxicity of ionic liquids on the growth, reproductive ability, and ATPase activity of earthworm

Mechanisms of Biological Effects of Ionic Liquids: From Single Cells to Multicellular Organisms

The review presents a detailed discussion of the evolving field studying interactions between ionic liquids (ILs) and biological systems. Originating from molten salt electrolytes to present multiapplication substances, ILs have found usage across various fields due to their exceptional physicochemical properties, including excellent tunability. However, their interactions with biological systems and potential influence on living organisms remain largely unexplored. This review examines the cytotoxic effects of ILs on cell cultures, biomolecules, and vertebrate and invertebrate organisms. Our understanding of IL toxicity, while growing in recent years, is yet nascent. The established findings include correlations between harmful effects of ILs and their ability to disturb cellular membranes, their potential to trigger oxidative stress in cells, and their ability to cause cell death via apoptosis. Future research directions proposed in the review include studying the distribution of various ILs within cellular compartments and organelles, investigating metabolic transformations of ILs in cells and organisms, detailed analysis of IL effects on proteins involved in oxidative stress and apoptosis, correlation studies between IL doses, exposure times and resulting adverse effects, and examination of effects of subtoxic concentrations of ILs on various biological objects. This review aims to serve as a critical analysis of the current body of knowledge on IL-related toxicity mechanisms. Furthermore, it can guide researchers toward the design of less toxic ILs and the informed use of ILs in drug development and medicine.

Microplastics - Back to Reality: Impact of Pristine and Aged Microplastics in Soil on Earthworm Eisenia fetida under Environmentally Relevant Conditions

Recently, studies have highlighted the potential danger for soil organisms posed by film-derived microplastics (MPs). However, the majority of those does not accurately reflect the field conditions and the degree of MP contamination that can be found in actual settings. To fill the gap between laboratory and field scenarios, the polyethylene (PE) plastic film was made into PE-MPs and aged. Toxicity and molecular mechanisms of pristine PE-MPs (PMPs) and aged PE-MPs (AMPs) with the concentration at 500 mg/kg of dry weight were determined after 14 days of exposure by measuring the oxidative stress, osmoregulation pressure, gut microbiota, and metabolic responses in earthworms under environmentally relevant conditions. Our research showed that, when compared to PMPs (13.13 ± 1.99 items/g), AMPs accumulated more (16.19 ± 8.47 items/g), caused more severe tissue lesions, and caused a higher increase of cell membrane osmotic pressure in earthworms' intestines. Furthermore, the proportion of probiotic bacteria Lactobacillus johnsonii in the gut bacterial communities was 24.26%, 23.26%, and 12.96%, while the proportion of pathogenic bacteria of the phylum Verrucomicrobia was 2.28%, 4.79%, and 10.39% in the control and PMP- and AMP-exposed earthworms, indicating that the decrease in number of probiotic bacteria and the increase in number of pathogenic bacteria were more pronounced in the gut of AMP- rather than PMP-exposed earthworms. Metabolomic analysis showed that AMP exposure reduced earthworm energy metabolites. Consequently, the constant need for energy may result in protein catabolism, which raises levels of some amino acids, disturbs normal cell homeostasis, causes changes of cell membrane osmolarity, and destroys the cell structure. Our studies showed that aged MPs, with the same characteristics as those found in the environment, have greater toxicity than pristine MPs. The results of this study broaden our understanding of the toxicological effects of MPs on soil organisms under environmentally relevant conditions.

Intergenerational toxic effects of parental exposure to [Cn mim]NO3 (n = 2,4,6) on nervous and skeletal development in zebrafish offspring

Ionic liquids (ILs) are thought to have negative effects on human health. Researchers have explored the effects of ILs on zebrafish development during the early stages, but the intergenerational toxicity of ILs on zebrafish development has rarely been reported. Herein, parental zebrafish were exposed to different concentrations (0, 12.5, 25, and 50 mg/L) of [Cn mim]NO3 (n = 2, 4, 6) for 1 week. Subsequently, the F1 offspring were cultured in clean water for 96 h. [Cn mim]NO3 (n = 2, 4, 6) exposure inhibited spermatogenesis and oogenesis in F0 adults, even causing obvious lacunae in the testis and atretic follicle oocytes in ovary. After parental exposure to [Cn mim]NO3 (n = 2, 4, 6), the body length and locomotor behavior were measured in F1 larvae at 96 hours post-fertilization (hpf). The results showed that the higher the concentration of [Cn mim]NO3 (n = 2, 4, 6), the shorter the body length and swimming distance, and the longer the immobility time. Besides, a longer alkyl chain length of [Cn mim]NO3 had a more negative effect on body length and locomotor behavior. RNA-seq analysis revealed several downregulated differentially expressed genes (DEGs)-grin1b, prss1, gria3a, and gria4a-enriched in neurodevelopment-related pathways, particularly the pathway for neuroactive ligand-receptor interaction. Moreover, several upregulated DEGs, namely col1a1a, col1a1b, and acta2, were mainly associated with skeletal development. Expression of DEGs was tested by RT-qPCR, and the outcomes were consistent with those obtained from RNA-Seq. We provide evidence showing the effects of parental exposure to ILs on the regulation of nervous and skeletal development in F1 offspring, demonstrating intergenerational effects.

Response pathways of superoxide dismutase and catalase under the regulation of triclocarban-triggered oxidative stress in Eisenia foetida: Comprehensive mechanism analysis based on cytotoxicity and binding model

Triclocarban (TCC) is an emerging environmental contaminant, posing potential ecological risks. Displaying a high accumulation effect and 120-day half-life in the soil environment, the toxic effects of TCC to soil organisms have been widely reported. Previous studies have confirmed that TCC can induce the oxidative stress and changes in superoxide dismutase (SOD) and catalase (CAT) activities in earthworms, but the underlying mechanisms of oxidative stress and disorder in antioxidant enzyme activities induced by TCC have not yet been elucidated. Here, we explored the multiple response mechanisms of SOD and CAT under the regulation of oxidative stress induced by TCC. Results indicated that higher-dose (0-2.0 mg/L) TCC exposure triggered the overproduction of ROS in Eisenia foetida coelomocytes, causing oxidative damage and a decrease in cell viability that was response to ROS accumulation. The TCC-induced inhibition of intracellular SOD/CAT activity was found under the regulation of oxidative stress (SOD: 29.2 %; CAT: 18.5 %), and this effect was blunted by antioxidant melatonin. At the same time, the interaction between antioxidative enzymes and TCC driven by various forces (SOD: electrostatic interactions; CAT: van der Waals forces and hydrogen bonding) led to inhibited SOD activity (9.84 %) and enhanced CAT activity (17.5 %). Then, to elucidate the binding mode of TCC, we explored the changes in SOD and CAT structure (protein backbone and secondary structure), the microenvironment of aromatic amino acids, and aggregation behavior through multispectral techniques. Molecular docking results showed that TCC inhibited SOD activity in a substrate competitive manner and enhanced CAT activity by the stabilizing effects of TCC on the heme groups. Collectively, this study reveals the response mechanisms of SOD/CAT under the regulation of TCC-triggered oxidative stress and shed a new light on revealing the toxic pathways of exogenous pollutants on antioxidant-related proteins function.

Visualizing and assessing the size-dependent oral uptake, tissue distribution, and detrimental effect of polystyrene microplastics in Eisenia fetida

Microplastics are widely distributed in the environment, their potential ecological risks on soil organism have attracted extensive attention, while the investigation of the size effect on its accumulation and toxicity in soil invertebrates are still lacking. In this study, we set out to explore the size-dependent effects of microplastics on soil invertebrates with different doses. Specifically, we investigated the effect of polystyrene (PS) microplastics on earthworm Eisenia fetida with three different sizes (70 nm, 1 μm and 10 μm) and exposure doses (0.5%, 5% and 10% w/w in food). Results showed that PS microplastics had no effects on the mortality of E. fetida, while an obvious growth inhibition with rising exposure concentrations was observed, especially under exposure of 70 nm plastic particles. Additionally, 70 nm PS microplastics induced more serious oxidative stress, energy depletion and histopathological damage on earthworms compared with larger sizes. The accumulation and distribution pattern of microplastics was size-dependent in earthworms after 3- and 7-day exposure as revealed by laser confocal microscopy. Notably, earthworms accumulated more micro-sized particles (MPs, 10 μm and 1 μm) but with less toxic responses, suggesting its weaker toxicity. The distribution pattern of MPs may explain the weak relation between accumulation and toxicity as they mainly distributed in epidermis of mid- and tail-section and the intestine of earthworm. In contrast, nano-sized particles (NPs, 70 nm) were more distributed in the head-section and subcutaneous tissue of the skin, which was in accordance with the obvious toxic responses found in earthworms exposing to NPs. Our study highlighted the importance of size in determining the accumulation, distribution and toxic effects of plastic particles towards soil invertebrates and advocates the necessity of ecological risk assessments of NPs.

Toxic mechanism on phenanthrene-triggered cell apoptosis, genotoxicity, immunotoxicity and activity changes of immunity protein in Eisenia fetida: Combined analysis at cellular and molecular levels

Phenanthrene (PHE) is a harmful organic contaminant and exists extensively in the soil environment. The accumulation of PHE would potentially threaten soil invertebrates, including earthworms, and the toxicity is also high. Currently, the possible mechanisms underlying apoptotic pathways induced by PHE and its immunotoxicity and genotoxicity in earthworms remain unclear. Thus, Eisenia fetida coelomocytes and immunity protein lysozyme (LYZ) were chosen as targeted receptors to reveal the apoptotic pathways, genotoxicity, and immunotoxicity triggered by PHE and its binding mechanism with LYZ, using cellular, biochemical, and molecular methods. Results indicated that PHE exposure can cause cell membrane damage, increase cell membrane permeability, and ultimately trigger mitochondria-mediated apoptosis. Increased 8-hydroxy-2-deoxyguanosine (8-OHdG) levels indicated PHE had triggered DNA oxidative damage in cells after PHE exposure. Occurrence of detrimental effects on the immune system in E. fetida coelomocytes due to decreased phagocytic efficacy and destroyed the lysosomal membrane. The LYZ activity in coelomocytes after PHE exposure was consistent with the molecular results, in which the LYZ activity was inhibited. After PHE binding, the protein structure (secondary structure and protein skeleton) and protein environment (the micro-environment of aromatic amino acids) of LYZ were destroyed, forming a larger particle size of the PHE-LYZ complex, and causing a significant sensitization effect on LYZ fluorescence. Molecular simulation indicated the key residues Glu 35, Asp 52, and Trp 62 for protein function located in the binding pocket, suggesting PHE preferentially binds to the active center of LYZ. Additionally, the primary driving forces for the binding interaction between PHE and LYZ molecule are hydrophobicity forces and hydrogen bonds. Taken together, PHE exposure can induce apoptosis by mitochondria-mediated pathway, destroy the normal immune system, and trigger DNA oxidative damage in earthworms. Besides, this study provides a comprehensive evaluation of phenanthrene toxicity to earthworms on molecular and cellular level.

Galleria mellonella: The Versatile Host for Drug Discovery, In Vivo Toxicity Testing and Characterising Host-Pathogen Interactions

Larvae of the greater wax moth, Galleria mellonella, are a convenient in vivo model for assessing the activity and toxicity of antimicrobial agents and for studying the immune response to pathogens and provide results similar to those from mammals. G. mellonella larvae are now widely used in academia and industry and their use can assist in the identification and evaluation of novel antimicrobial agents. Galleria larvae are inexpensive to purchase and house, easy to inoculate, generate results within 24–48 h and their use is not restricted by legal or ethical considerations. This review will highlight how Galleria larvae can be used to assess the efficacy of novel antimicrobial therapies (photodynamic therapy, phage therapy, metal-based drugs, triazole-amino acid hybrids) and for determining the in vivo toxicity of compounds (e.g., food preservatives, ionic liquids) and/or solvents (polysorbate 80). In addition, the disease development processes are associated with a variety of pathogens (e.g., Staphylococcus aureus, Listeria monocytogenes, Aspergillus fumigatus, Madurella mycotomatis) in mammals are also present in Galleria larvae thus providing a simple in vivo model for characterising disease progression. The use of Galleria larvae offers many advantages and can lead to an acceleration in the development of novel antimicrobials and may be a prerequisite to mammalian testing.

Comprehensive Interrogation on Acetylcholinesterase Inhibition by Ionic Liquids Using Machine Learning and Molecular Modeling

Quantitative structure-activity relationship (QSAR) modeling can be used to predict the toxicity of ionic liquids (ILs), but most QSAR models have been constructed by arbitrarily selecting one machine learning method and ignored the overall interactions between ILs and biological systems, such as proteins. In order to obtain more reliable and interpretable QSAR models and reveal the related molecular mechanism, we performed a systematic analysis of acetylcholinesterase (AChE) inhibition by 153 ILs using machine learning and molecular modeling. Our results showed that more reliable and stable QSAR models (R² > 0.85 for both cross-validation and external validation) were obtained by combining the results from multiple machine learning approaches. In addition, molecular docking results revealed that the cations and organic anions of ILs bound to specific amino acid residues of AChE through noncovalent interactions such as π interactions and hydrogen bonds. The calculation results of binding free energy showed that an electrostatic interaction (ΔE_ele < -285 kJ/mol) was the main driving force for the binding of ILs to AChE. The overall findings from this investigation demonstrate that a systematic approach is much more convincing. Future research in this direction will help design the next generation of biosafe ILs.

Toxic mechanism on phenanthrene-induced cytotoxicity, oxidative stress and activity changes of superoxide dismutase and catalase in earthworm (Eisenia foetida): A combined molecular and cellular study

Phenanthrene (PHE) is an important organic compound, which is widespread in the soil environment and exhibits potential threats to soil organisms. Toxic effects of PHE to earthworms have been extensively studied, but toxic mechanisms on PHE-induced cytotoxicity and oxidative stress at the molecular and cellular levels have not been reported yet. Therefore, we explored the cytotoxicity and oxidative stress caused by PHE in earthworm coelomocytes and the interaction mechanism between PHE and the major antioxidant enzymes SOD/CAT. It was shown that high-dose PHE exposure induced the intracellular reactive oxygen species (ROS) generation, mediated lipid peroxidation, reduced total antioxidant capacity (T-AOC) in coelomocytes, and triggered oxidative stress, thus resulted in a strong cytotoxicity at higher concentrations (0.6-1.0 mg/L). The intracellular SOD/CAT activity in cells after PHE exposure were congruent with that in molecular levels, which the activity of SOD enhanced and CAT inhibited. Spectroscopic studies showed the SOD/CAT protein skeleton and secondary structure, as well as the micro-environment of aromatic amino acids were changed after PHE binding. Molecular docking indicated PHE preferentially docked to the surface of SOD. However, the key residues Tyr 357, His 74, and Asn 147 for activity were in the binding pocket, indicating PHE more likely to dock to the active center of CAT. In addition, H-bonding and hydrophobic force were the primary driving force in the binding interaction between PHE and SOD/CAT. This study indicates that PHE can induce cytotoxicity and oxidative damage to coelomocytes and unearthes the potential effects of PHE on earthworms.

New Findings of Ferrate(VI) Oxidation Mechanism from Its Degradation of Alkene Imidazole Ionic Liquids

Chemical reactivity, kinetics, degradation pathways and mechanisms, and ecotoxicity of the oxidation of 1-vinyl-3-ethylimidazolium bromide ([VEIm]Br), the most common alternative to organic solvents, by Fe(VI) (HFeO₄^-) were studied by lab experiments and theoretical calculations. Results show that Fe(VI) can efficiently remove VEIm through the dioxygen transfer-hydrolysis mechanism, which has not been reported yet. The reactivity of VEIm toward Fe(VI) mainly depends on the double bonds in the side chain of VEIm. The second-order rate constant for VEIm was 629.45 M^-1 s^-1 at pH 7.0 and 25 °C. Typical water constituents, except for SO₃^2-, Cl^-, and Cu²⁺, had no obvious effects on the oxidation. The oxidation products were determined by high-performance liquid chromatography hybrid quadrupole time-of-flight mass spectrometry, which proves that there were interactions between the oxidation intermediates of the anion and cation parts of [VEIm]Br during the degradation process. The structures of related products and oxidation mechanisms were further rationalized by theoretical calculations. The ecotoxicity of products from the three oxidation pathways all showed a trend of increase after the initial decrease. We hope that the findings of this work can give researchers some new inspirations on Fe(VI) degradation of other alkene-containing contaminants.

Transcriptomics and metabolomics reveal Ca2+ overload and osmotic imbalance-induced neurotoxicity in earthworms (Eisenia fetida) under tri-n-butyl phosphate exposure

Tri-n-butyl phosphate (TNBP) is mass-produced and widely utilized in many products, which has increasingly drawn concern about its potential environmental risks. However, little is known about the toxic mechanism on soil-dwelling organisms caused by TNBP. In this study, earthworms (Eisenia fetida) were exposed to environmentally relevant or higher concentrations of TNBP (0, 0.1, 1, and 10 mg/kg) in artificial soil for 14 days. Our results showed that TNBP accumulated in earthworm nervous tissue (cerebral ganglions). In addition, the content of glutamate in cerebral ganglions decreased compared to the control (p < 0.05). The concentration of Ca²⁺ in earthworm cerebral ganglions increased. However, both Na⁺/K⁺-ATPase and Ca²⁺-ATPase activities were significantly reduced compared to the control (p < 0.05), which led to neurotoxicity in earthworm nervous tissue. Furthermore, the transcriptome and metabolomics revealed the toxic mechanism in earthworm nervous tissue caused by TNBP. Results indicated that the main neurotoxicity mechanisms induced by TNBP were an osmotic imbalance and Ca²⁺ overload in cerebral ganglions. Our findings fill a gap in the literature on neurotoxicity mechanisms of earthworm response to TNBP exposure and contribute to a better understanding of the adverse effects of TNBP on soil-dwelling organisms in terrestrial ecological systems.

Mechanisms of action of ionic liquids on living cells: the state of the art

Ionic liquids (ILs) are a relatively new class of organic electrolytes composed of an organic cation and either an organic or inorganic anion, whose melting temperature falls around room-temperature. In the last 20 years, the toxicity of ILs towards cells and micro-organisms has been heavily investigated with the main aim to assess the risks associated with their potential use in (industrial) applications, and to develop strategies to design greener ILs. Toxicity, however, is synonym with affinity, and this has stimulated, in turn, a series of biophysical and chemical-physical investigations as well as few biochemical studies focused on the mechanisms of action (MoAs) of ILs, key step in the development of applications in bio-nanomedicine and bio-nanotechnology. This review has the intent to present an overview of the state of the art of the MoAs of ILs, which have been the focus of a limited number of studies but still sufficient enough to provide a first glimpse on the subject. The overall picture that emerges is quite intriguing and shows that ILs interact with cells in a variety of different mechanisms, including alteration of lipid distribution and cell membrane viscoelasticity, disruption of cell and nuclear membranes, mitochondrial permeabilization and dysfunction, generation of reactive oxygen species, chloroplast damage (in plants), alteration of transmembrane and cytoplasmatic proteins/enzyme functions, alteration of signaling pathways, and DNA fragmentation. Together with our earlier review work on the biophysics and chemical-physics of IL-cell membrane interactions (Biophys. Rev. 9:309, 2017), we hope that the present review, focused instead on the biochemical aspects, will stimulate a series of new investigations and discoveries in the still new and interdisciplinary field of "ILs, biomolecules, and cells."

Ionic Liquids Toxicity-Benefits and Threats

Ionic liquids (ILs) are solvents with salt structures. Typically, they contain organic cations (ammonium, imidazolium, pyridinium, piperidinium or pyrrolidinium), and halogen, fluorinated or organic anions. While ILs are considered to be environmentally-friendly compounds, only a few reasons support this claim. This is because of high thermal stability, and negligible pressure at room temperature which makes them non-volatile, therefore preventing the release of ILs into the atmosphere. The expansion of the range of applications of ILs in many chemical industry fields has led to a growing threat of contamination of the aquatic and terrestrial environments by these compounds. As the possibility of the release of ILs into the environment s grow systematically, there is an increasing and urgent obligation to determine their toxic and antimicrobial influence on the environment. Many bioassays were carried out to evaluate the (eco)toxicity and biodegradability of ILs. Most of them have questioned their "green" features as ILs turned out to be toxic towards organisms from varied trophic levels. Therefore, there is a need for a new biodegradable, less toxic "greener" ILs. This review presents the potential risks to the environment linked to the application of ILs. These are the following: cytotoxicity evaluated by the use of human cells, toxicity manifesting in aqueous and terrestrial environments. The studies proving the relation between structures versus toxicity for ILs with special emphasis on directions suitable for designing safer ILs synthesized from renewable sources are also presented. The representants of a new generation of easily biodegradable ILs derivatives of amino acids, sugars, choline, and bicyclic monoterpene moiety are collected. Some benefits of using ILs in medicine, agriculture, and the bio-processing industry are also presented.

Copper accumulation and toxicity in earthworms exposed to CuO nanomaterials: Effects of particle coating and soil ageing

Engineered nanomaterials (ENMs) may be functionalised with a surface coating to enhance their properties, but the ecotoxicity of the coatings and how hazard changes with ageing in soil is poorly understood. This study determined the toxic effect of CuO ENMs with different chemical coatings on the earthworm (Eisenia fetida) in fresh soil, and then after one year in aged soil. In both experiments, earthworms were exposed for 14 days to the CuO materials at nominal concentrations of 200 and 1000 mg Cu kg^-1 dry weight and compared to CuSO₄. In the fresh soil experiment, CuO-COOH was found to be the most acutely toxic of the nanomaterials (survival, 20 ± 50%), with tenfold increase of total Cu in the earthworms compared to controls. Sodium pump activity was reduced in most CuO ENM treatments, although not in the CuSO₄ control. There was no evidence of glutathione depletion or the induction of superoxide dismutase (SOD) activity in any treatment. Histology showed a mild hypoplasia of mucous cells in the epidermis with some nanomaterials. In the aged soil, the CuO-NH₄⁺ was the most acutely toxic ENM (survival 45 ± 3%) and Cu accumulation was lower in the earthworms than in the fresh soil study. Depletion of tissue Mn and Zn concentrations were seen in earthworms in aged soil, while no significant effects on sodium pump or total glutathione were observed. Overall, the study showed some coating-dependent differences in ENM toxicity to earthworms which also changed after a year of ageing the soil.

Environmental Impact of Ionic Liquids: Recent Advances in (Eco)toxicology and (Bio)degradability

This Review aims to integrate the most recent and pertinent data available on the (bio)degradability and toxicity of ionic liquids for global and critical analysis and on the conscious use of these compounds on a large scale thereafter. The integrated data will enable focus on the recognition of toxicophores and on the way the community has been dealing with them, with the aim to obtain greener and safer ionic liquids. Also, an update of the most recent biotic and abiotic methods developed to overcome some of these challenging issues will be presented. The review structure aims to present a potential sequence of events that can occur upon discharging ionic liquids into the environment and the potential long-term consequences.

Assessment of ionic liquids' toxicity through the inhibition of acylase I activity on a microflow system

Acylase I (ACY I) plays a role in the detoxication and bioactivation of xenobiotics as well in other physiological functions. In this context, an automated ACY I assay for the evaluation of ionic liquids' (ILs) toxicity was developed. The assay was implemented in a sequential injection analysis (SIA) system and was applied to eight commercially available ILs. The SIA methodology was based on the deacetylation of N-acetyl-l-methionine with production of l-methionine, which was determined using fluorescamine. ACY I inhibition in the presence of ILs was monitored by the decrease of fluorescence intensity. The obtained results confirmed the influence of ILs' structural elements on its toxicity and revealed that pyridinium and phosphonium cations, longer alkyl side chains and tetrafluoroborate anion displayed higher toxic effect on enzyme activity. The developed methodology proved to be robust and exhibited good repeatability (RSD < 1.3%, n = 10), leading also to a reduction of reagents consumption and effluents production. Thus, it is expected that the proposed assay can be used as a novel tool for ILs' toxicity screening.

Biological Activity of Ionic Liquids and Their Application in Pharmaceutics and Medicine

Ionic liquids are remarkable chemical compounds, which find applications in many areas of modern science. Because of their highly tunable nature and exceptional properties, ionic liquids have become essential players in the fields of synthesis and catalysis, extraction, electrochemistry, analytics, biotechnology, etc. Apart from physical and chemical features of ionic liquids, their high biological activity has been attracting significant attention from biochemists, ecologists, and medical scientists. This Review is dedicated to biological activities of ionic liquids, with a special emphasis on their potential employment in pharmaceutics and medicine. The accumulated data on the biological activity of ionic liquids, including their antimicrobial and cytotoxic properties, are discussed in view of possible applications in drug synthesis and drug delivery systems. Dedicated attention is given to a novel active pharmaceutical ingredient-ionic liquid (API-IL) concept, which suggests using traditional drugs in the form of ionic liquid species. The main aim of this Review is to attract a broad audience of chemical, biological, and medical scientists to study advantages of ionic liquid pharmaceutics. Overall, the discussed data highlight the importance of the research direction defined as "Ioliomics", studies of ions in liquids in modern chemistry, biology, and medicine.

Biochemical responses and DNA damage in earthworms (Eisenia fetida) induced by ionic liquid [omim]PF6

Ionic liquids that are not that "green" to many organisms have recently been identified. This study examined the subchronic toxicity of the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([omim]PF6) to earthworms (Eisenia fetida). Earthworms were exposed for a 28-day period (sampled on days 7, 14, 21, and 28) at concentrations of 0, 5, 10, 20, and 40 mg/kg. The levels of reactive oxygen species (ROS), antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD)), detoxifying enzyme (glutathione S-transferase (GST)), lipid peroxidation, and DNA damage were measured. ROS significantly accumulated in all the treatment groups; the maximum ROS content was 51.9% higher than the control at 40 mg/kg [omim]PF6 on day 28. Increased SOD activities attenuated over the time of exposure, while the CAT activities of the treatment groups were similar to the controls, except on day 14. Furthermore, the activities of POD and GST were stimulated. Lipid peroxidation in earthworms was not apparent at 5 and 10 mg/kg [omim]PF6 but was quite obvious at 40 mg/kg [omim]PF6. In addition, DNA damage was dose- and time-dependent. In conclusion, [omim]PF6 caused oxidative stress and genotoxicity in earthworms.

Galleria mellonella as a novel in vivo model for assessment of the toxicity of 1-alkyl-3-methylimidazolium chloride ionic liquids

The larval form of the Greater Wax Moth (Galleria mellonella) was evaluated as a model system for the study of the acute in vivo toxicity of 1-alkyl-3-methylimidazolium chloride ionic liquids. 24-h median lethal dose (LD50) values for nine of these ionic liquids bearing alkyl chain substituents ranging from 2 to 18 carbon atoms were determined. The in vivo toxicity of the ionic liquids was found to correlate directly with the length of the alkyl chain substituent, and the pattern of toxicity observed was in accordance with previous studies of ionic liquid toxicity in other living systems, including a characteristic toxicity 'cut-off' effect. However, G. mellonella appeared to be more susceptible to the toxic effects of the ionic liquids tested, possibly as a result of their high body fat content. The results obtained in this study indicate that G. mellonella represents a sensitive, reliable and robust in vivo model organism for the evaluation of ionic liquid toxicity.

Chronic effects of the ionic liquid [C4mim][Cl] towards the microalga Scenedesmus quadricauda

Chronic effects of the ionic liquid [C4mim][Cl] (mp 73 °C) towards the microalga, Scenedesmus quadricauda were studied by flow cytometry, monitoring multiple endpoints of cell density, esterase activity, membrane integrity, reactive oxygen species and chlorophyll fluorescence. Toxicity was clearly in evidence, and although increased esterase activity indicated hormesis during initial exposure to [C4mim][Cl], inhibition of both esterase activity and chlorophyll fluorescence became apparent after 3 days. Cell density was also decreased by culturing with [C4mim][Cl], but this effect was clearly concentration-dependent and only became significant during the second half of the experiment. In contrast, [C4mim][Cl] had only a modest effect on reactive oxygen species (ROS) and caused little damage to cell membranes.

Selected issues related to the toxicity of ionic liquids and deep eutectic solvents--a review

Green Chemistry plays a more and more important role in implementing rules of sustainable development to prevent environmental pollution caused by technological processes, while simultaneously increasing the production yield. Ionic liquids (ILs) and deep eutectic solvents (DESs) constitute a very broad group of substances. Apart from many imperfections, ILs and DESs have been the most promising discoveries in the world of Green Chemistry in recent years. The main advantage of ILs is their unique physicochemical properties-they are very desirable from the technological point of view, but apart from these benefits, ILs appear to be highly toxic towards organisms from different trophic levels. DES areas of usage are very spread, because they cover organic synthesis, extraction processes, electrochemistry, enzymatic reactions and many others. Moreover, DESs seem to be a less toxic alternative to ionic liquids. New possibilities of applications and future development trends are sought and presented, including such important solutions of life branches as pharmaceuticals' production and medicine.

Effects of alkyl-imidazolium ionic liquid [Omim]Cl on the functional diversity of soil microbial communities

As low-temperature molten salts, ionic liquids (ILs) were considered to be "green" solvents and have begun to see large-scale applications in the chemical reactions, in separation processes, in electrochemistry studies, etc. In recent years, the toxicity of ILs has started to draw attention. To evaluate the effects of the ionic liquid [Omim]Cl on indigenous microbial community in soil, Biolog-ECO plate method were used with the addition of four different concentrations of [Omim]Cl after four different incubation periods (7, 14, 21, 28 days). The present results showed that the average well color development (AWCD) was strongly activated when the soil was contaminated with [Omim]Cl in the early stages of the incubation. However, the activation effect disappeared with extended incubation time. Therefore, the toxic effects of the alkyl-imidazolium ionic liquid ([Omim]Cl) on the functional diversity of soil microbial communities may be reversible. In addition, the kinetic characteristics of microorganisms that used different categories of carbon sources indicated that phenolic compounds were the main C source in the sample soil.

Toxicity of ionic liquids: eco(cyto)activity as complicated, but unavoidable parameter for task-specific optimization

Rapid progress in the field of ionic liquids in recent decades led to the development of many outstanding energy-conversion processes, catalytic systems, synthetic procedures, and important practical applications. Task-specific optimization emerged as a sharpening stone for the fine-tuning of structure of ionic liquids, which resulted in unprecedented efficiency at the molecular level. Ionic-liquid systems showed promising opportunities in the development of green and sustainable technologies; however, the chemical nature of ionic liquids is not intrinsically green. Many ionic liquids were found to be toxic or even highly toxic towards cells and living organisms. In this Review, we show that biological activity and cytotoxicity of ionic liquids dramatically depend on the nature of a biological system. An ionic liquid may be not toxic for particular cells or organisms, but may demonstrate high toxicity towards another target present in the environment. Thus, a careful selection of biological activity data is a must for the correct assessment of chemical technologies involving ionic liquids. In addition to the direct biological activity (immediate response), several indirect effects and aftereffects are of primary importance. The following principal factors were revealed to modulate toxicity of ionic liquids: i) length of an alkyl chain in the cation; ii) degree of functionalization in the side chain of the cation; iii) anion nature; iv) cation nature; and v) mutual influence of anion and cation.

Toxicological evaluation of magnetic ionic liquids in human cell lines

Magnetic ionic liquids (MILs) are new solvents with an interesting broad of applications however their toxicity is still an open issue. In this paper we report the toxicity of [C(8)MIM] and [Choline-C(n)] based magnetic ionic liquids assessed in two human cell lines: normal skin fibroblasts (CRL-1502) and colorectal adenocarcinoma cells (CaCo-2), acquiring this last characteristics of human enterocytes after differentiation. The results showed that [CoCl(4)] and [MnCl(4)] are more prone to generate cytotoxicity.

Automated high-throughput Vibrio fischeri assay for (eco)toxicity screening: application to ionic liquids

An automated high-throughput Vibrio fischeri assay was developed and further applied to the evaluation of ionic liquids (ILs) (eco)toxicity. The assay was based on the reduction of bacterial bioluminescence in the presence of test compounds and the results were presented as EC(50). The assays were performed with eight commercially available ILs with distinct cationic head groups, alkyl side chains and anions. EC(50) values between 6.5 and 691.9 mmol L(-1) were obtained for the tested ILs, being hmim [Cl] the most toxic and bmim [Cl] the less toxic ones, confirming the influence of the different structural elements. Moreover, all the tested ILs exhibited a (eco)toxicity lower than Cu(II), used as a positive control during the optimization and analysis steps. The automated assay assured the precise control of the contact time between V. fischeri and test compound by means of a simple protocol that guaranteed adequate aspiration and handling of the solutions as well as the precise implementation of a computer controlled stop period. Furthermore, a significant reduction of the assay costs was achieved through automation mainly by a drastic reduction of the volume of bacterial suspension and test compound. The methodology was validated by comparison with a microplate assay; it was stated that the results, obtained after a 3min contact time, changed proportionally relatively to Cu(II) in both assays. This confirmed the applicability of the methodology as an (eco)toxicity screening assay, with reduction of time and increase of robustness and repeatability (n=10; rsd<1.1%). It is expected that due to its simplicity and reduced cost the developed assay can be integrated in the early stage of development of new compounds as a rapid screening test.

Significant contributions of ionic liquids containing tetrafluoroborate and trifluoromethanesulfonate to antagonisms and synergisms in multi-component mixtures

Recent toxicity studies on ionic liquids (ILs) are challenging their postulation as green solvents. Previous reports on mixtures containing ILs make it urgent to reveal the responsible components for the toxicity interactions. For that purpose, eight ILs, four consisting of 1-ethyl-3-methylimidazolium ([emim]) and the others of 1-butyl-3-methylimidazolium ([bmim]), were selected as mixture components. The concentrations of eight ILs in mixtures were set up by the uniform design. The inhibition toxicities of single ILs and mixtures to Vibrio qinghaiensis sp.-Q67 were determined by microplate toxicity analysis. Combined toxicity was evaluated by the difference between the effects observed and predicted by the concentration addition model. Using the variable selection and modeling method based on the prediction (VSMP), it was found that the antagonism/synergism induced by the mixtures of eight ILs was related to [emim]BF(4)/[emim]CF(3)SO(3). To further illustrate the toxicity interactions, eight ILs were split into two mixture groups, one containing four [emim]-based ILs and the other four [bmim]-based ILs. The [emim]-group exhibited synergism while [bmim]-group resulted in antagonism. It was interesting that both the synergism and antagonism well related to the concentration ratio of ILs with BF(4)(-). When ILs with BF(4)(-) were deleted from corresponding mixtures, the toxicity interactions (synergism/antagonism) disappeared.