Oxidative stress and genotoxic effects in earthworms induced by five imidazolium bromide ionic liquids with different alkyl chains

Environmental Implications of Ionic Liquid and Deep Eutectic Solvent in Geothermal Application: Comparing Traditional and New Approach Methods

The significant surge of ionic liquids (ILs) research over the past decade has led to the formation of various novel ionic liquid compounds and their diverse applications. Enhanced geothermal systems (EGS) for geothermal power generation are an emerging IL application as a heat extraction fluid. The once widely held belief in the environmentally friendly characteristics of ionic liquids, mainly due to their insignificant vapor pressure, is now being scrutinized. It has become apparent that while ILs do not readily evaporate into the atmosphere, they are not guaranteed to remain entirely isolated from the environment. Recent attention has been directed toward toxicological studies, including ecotoxicity impacts, with the long-accepted assumption of ILs having low toxicity being invalid. This paper aims to shed light on the toxicity of hexylepyradinium bromide (HPyBr) IL and a deep eutectic solvent (DES) comprising choline chloride with magnesium chloride hexahydrate (ChCl:MgCl2·6H2O) to five test species, an algal species (Raphidocelis subcapitata), the water flea (Ceriodaphnia dubia and Daphina magna), the fathead minnow (Pimephales promelas), and the earthworm (Eisenia fetida), to measure acute and chronic toxicity. Additionally, new approach methods (NAMs) are presented using the fathead minnow embryo and the rainbow trout (Oncorhynchus mykiss) gill cell line and the RTgill-W1 assay to compare sensitivity across species. Overall, ChCl:MgCl2·6H2O displayed lower toxicity, while HPyBr demonstrated higher toxicity, highlighting the need for caution in handling it to prevent harm to aquatic ecosystems. Comparative analysis underscored the potential threat of ChCl:MgCl2·6H2O to aquatic life, highlighting the cumulative effects of the environmental components.

The Dynamics of Allelochemicals and Phytotoxicity in Eisenia fetida during the Decomposition of Eucalyptus grandis Litter

Allelopathy is an underlying and controversial mechanism for detrimental environmental effects in the management of Eucalyptus plantations. However, little attention has been paid to the dynamics of allelochemicals and phytotoxicity in soil fauna during litter decomposition. To explore the relationship between the dynamics of phytotoxicity and allelochemicals, a decomposition experiment was conducted using 4-year-old and 8-year-old Eucalyptus grandis litter (0, 10, 20, 30, and 45 days). The acute toxicity of Eisenia fetida was assessed, and a chemical analysis of the eucalyptus leaves was performed. Biochemical markers, including total protein, acetylcholinesterase (AChE) activity, and oxidative stress levels (SOD and MDA) were measured. A comet assay was used to determine DNA damage in E. fetida cells. The results showed that after 20-30 days of decomposition, E. grandis litter exhibited stronger phytotoxic effects on E. fetida in terms of growth and biochemical levels. After 20 days of decomposition, the weight and total protein content of E. fetida first decreased and then increased over time. SOD activity increased after 20 days but decreased after 30 days of decomposition before increasing again. MDA content increased after 20 days, then decreased or was stable. AChE activity was inhibited after 30 days of decomposition and then increased or stabilized with further decomposition. Soluble allelochemicals, such as betaine, chlorogenic acid, and isoquercitrin, significantly decreased or disappeared during the initial decomposition stage, but pipecolic acid significantly increased, along with newly emerging phenolic fractions that were present. More allelochemicals were released from 8-year-old litter than from 4-year-old E. grandis litter, resulting in consistently more severe phytotoxic responses and DNA damage in E. fetida. Scientific management measures, such as the appropriate removal of leaf litter in the early stages of decomposition, might help support greater biodiversity in E. grandis plantations.

Bioconcentration, oxidative stress and molecular mechanism of the toxic effect of acetamiprid exposure on Xenopus laevis tadpoles

Acetamiprid is a neonicotinoid commonly detected in aquatic ecosystems, with residual concentrations of up to 0.41 mg/L in surface water, posing a threat to the health of nontarget aquatic organisms. However, studies on the potential toxicity and underlying mechanisms of action of acetamiprid on nontarget aquatic organisms are limited. This study investigated the acute and short-term toxicity of acetamiprid to Xenopus laevis tadpoles. A 96-h acute toxicity test determined the LC50 of acetamiprid to be 32.1 mg/L. After 28 days of exposure to 1/10 and 1/100 LC50 concentrations, tadpole samples were collected for bioconcentration elimination analysis, biochemical analyses, transcriptomics, and metabolomics studies to comprehensively evaluate the toxic effects of acetamiprid and its underlying mechanisms. The results, indicating bioconcentration factors (BCFs) < 1, suggest that acetamiprid has a low bioconcentration in tadpoles. Additionally, oxidative stress was observed in treated Xenopus laevis tadpoles. Transcriptomic and nontargeted metabolomic analyses identified 979 differentially expressed genes (DEGs) and 95 differentially metabolites in the 0.321 mg/L group. The integrated analysis revealed that disruption of purine and amino acid metabolic pathways potentially accounts for acetamiprid-induced toxic effects in tadpoles. The disruptive effects of acetamiprid on valine, leucine and isoleucine biosynthesis; and aminoacyl-tRNA biosynthesis metabolic pathways in tadpoles were validated through targeted metabolomics analysis. These findings are crucial for assessing the risk of acetamiprid to nontarget aquatic organisms.

Butyl benzyl phthalate exposure impact on the gut health of Metaphire guillelmi

Agricultural films are extensively utilized in high-intensity agriculture, with China's annual usage reaching 1.5 million tons. Unfortunately, the recovery rate is less than 60%, leading to an inevitable accumulation of plastic mulch in agricultural soils. This accumulation primarily introduces butyl benzyl phthalate (BBP) into soil ecosystems, whose specific effects remain largely unclear, thereby posing potential risks. The present study focuses on the exposure impact of BBP on earthworms, Metaphire guillelmi, a commonly found endogenic earthworm within real farmland, as it provides insight into the direct interaction between biota gut health and contaminants. Specifically, we studied the biomarkers related to oxidative stress, the digestive system, and neurotoxicity within the gut of Metaphire guillelmi, and the integrated biological response (IBR) index was utilized to track these markers at different timeframes after BBP exposures. Our findings indicate that BBP exposures lead to oxidative damage, digestive system inhibition, and neurotoxicity, with IBR indexes of 14.6 and 17.3 on the 14th and 28th days, respectively. Further, the underlying mechanisms at a molecular level through molecular docking were investigated. The results showed that the most unstable interaction was with the Na+K+-ATPase (binding energy: -2.25 kcal-1), while BBP displayed stable bonds with superoxide dismutase and 8-hydroxydeoxyguanosine via hydrogen bonds and hydrophobic interaction. These interactions resulted in changes in protein conformation and their normal physiological functions, offering new insights into the molecular mechanism underlying enzymatic activity changes. This study has significant implications for the prediction of toxicity, environmental risk assessment, and the establishment of regulations related to BBP.

Immobilization of Candida antarctica lipase B on ILs modified CNTs with different chain lengths: Regulation of substrate tunnel "Leucine gating"

Ionic liquids (ILs) have been widely used as chemical modifiers to modify the carriers and thus improve the efficiency, activity and stability of the enzymes. However, as thousands of ILs have been found up to date, it's a huge work for screening and designing suitable ILs for immobilization of enzymes. Moreover, the mechanism of improving enzymes catalytic performance is still remain ambiguous. Thus, this study investigated the impact of ILs with different chain lengths on the enzymatic properties of Candida antarctica lipase B (CALB). Molecular dynamics simulations were employed to examine the interaction between ILs modified CNTs and CALB, as well as their effects on CALB's structure. The results revealed that ILs with different chain lengths significantly influenced the absorption orientation of CALB. Tunnel analysis identified a key role for Leu278 in regulating the open or closed state of Tunnel 2 during CALB's catalytic cycle. The weak interaction analysis demonstrated that ILs with suitable chain lengths provided spatial freedom and formed strong interactions with CNTs and ILs (vdW and hbond). This led to a conformational flip of Leu278, stabilizing the open state of Tunnel 2 and improving the activity and stability of immobilized CALB. This study provides novel insights into the design of new green modifiers to modulate carrier performance and obtain immobilized enzymes with better performance, and establishes a theoretical basis for the design and selection of modifiers for ILs in future work.

Toxicity of ionic liquids against earthworms (Eisenia fetida)

Ionic liquids (ILs) are widely used in frontier fields because of their highly tunable properties. Although ILs may have adverse effects on organisms, few studies have focused on their effect on earthworm gene expression. Herein we investigated the toxicity mechanism of different ILs towards Eisenia fetida using transcriptomics. Earthworms were exposed to soil containing different concentrations and types of ILs, and behavior, weight, enzymatic activity and transcriptome were analyzed. Earthworms exhibited avoidance behavior towards ILs and growth was inhibited. ILs also affected antioxidant and detoxifying enzymatic activity. These effects were concentration and alkyl chain length-dependent. Analysis of intrasample expression levels and differences in transcriptome expression levels showed good parallelism within groups and large differences between groups. Based on functional classification analysis, we speculate that toxicity mainly occurs through translation and modification of proteins and intracellular transport functions, which affect protein-related binding functions and catalytic activity. KEGG pathway analysis revealed that ILs may damage the digestive system of earthworms, among other possible pathological effects. Transcriptome analysis reveals mechanisms that cannot be observed by conventional toxicity endpoints. This is useful to evaluate the potential environmental adverse effects of the industrial use of ILs.

Toxicity assessment of lead, nickel and cadmium on zebra fish augmented with Bacillus xiamenensis VITMSJ3: An insight on the defense mechanism against oxidative stress due to heavy metals

Increase urbanization in recent years has let to discharge of heavy metals into the environment which has caused severe impacts on soil as well as water. Therefore the current study was aimed to assess the toxicity of lead (Pb), nickel (Ni), and cadmium (Cd) from the contaminated water using zebra fish Danio rerio and detoxification of metals upon augmentation with Bacillus xiamenensis. Exposure doses till 150 mg L^-1 of Pb, Ni and Cd in water showed lethal effects on fish. Similarly the histopathological analysis showed severe tissue disruption in the gills and liver which were less upon supplementation with bacterial strain VITMSJ3. On the 20th day, the uptake concentration of Pb, Ni and Cd in zebra fish was found to be 87 mg L^-1, 89 mg L^-1 and 91 mg L^-1 respectively with VITMSJ3, from the water. Antioxidant enzymatic activities showed an increase upon bacterial supplementation, which reduced the oxidative stress. Further SEM-EDAX analysis confirmed the presence of Pb, Ni and Cd ions adsorbed on the gills. The results clearly showed less oxidative damages in fish with increased head and reduced tail %. Overall, the results showed a significant difference (p < 0.05) among the treatments compared with the control.

Oxidative stress and inflammation caused by 1-tetradecyl-3-methylimidazolium tetrafluoroborate in rat livers

The purpose of this study was to elucidate the mechanism underlying toxicity in the livers of male and female rats after treatment with 1-tetradecyl-3-methylimidazolium tetrafluoroborate ([C₁₄mim]BF₄, 0 [control], 12.5, 25, or 50 mg/kg) for 90 days. The results showed that [C₁₄mim]BF₄ exposure led to a high level of ROS and MDA in rat livers and the lower expression of Nrf2 and its downstream related antioxidant proteins. In addition, the expression of NF-κB p65 and the levels of inflammatory cytokines were upregulated in exposure groups rats' liver. After 30 days of cessation of exposure, the liver injury of rats in the 50 mg/kg exposure group was alleviated, and the above indicators were improved to varying degrees. The paper shows that [C₁₄mim]BF₄ could damage rat liver through oxidative stress and inflammatory pathway.

Density Functional Method Study on the Cooperativity of Intermolecular H-bonding and π-π+ Stacking Interactions in Thymine-[Cnmim]Br (n = 2, 4, 6, 8, 10) Microhydrates

The exploration of the ionic liquids’ mechanism of action on nucleobase’s structure and properties is still limited. In this work, the binding model of the 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br, n = 2, 4, 6, 8, 10) ionic liquids to the thymine (T) was studied in a water environment (PCM) and a microhydrated surroundings (PCM + wH2O). Geometries of the mono-, di-, tri-, and tetra-ionic thymine (T-wH2O-y[Cnmim]+-xBr−, w = 5~1 and x + y = 0~4) complexes were optimized at the M06-2X/6-311++G(2d, p) level. The IR and UV-Vis spectra, QTAIM, and NBO analysis for the most stable T-4H2O-Br−-1, T-3H2O-[Cnmim]+-Br−-1, T-2H2O-[Cnmim]+-2Br−-1, and T-1H2O-2[Cnmim]+-2Br−-1 hydrates were presented in great detail. The results show that the order of the arrangement stability of thymine with the cations (T-[Cnmim]+) by PCM is stacking > perpendicular > coplanar, and with the anion (T-Br−) is front > top. The stability order for the different microhydrates is following T-5H2O-1 < T-4H2O-Br−-1 < T-3H2O-[Cnmim]+-Br−-1 < T-2H2O-[Cnmim]+-2Br−-1 < T-1H2O-2[Cnmim]+-2Br−-1. A good linear relationship between binding EB values and the increasing number (x + y) of ions has been found, which indicates that the cooperativity of interactions for the H-bonding and π-π+ stacking is varying incrementally in the growing ionic clusters. The stacking model between thymine and [Cnmim]+ cations is accompanied by weaker hydrogen bonds which are always much less favorable than those in T-xBr− complexes; the same trend holds when the clusters in size grow and the length of alkyl chains in the imidazolium cations increase. QTAIM and NBO analytical methods support the existence of mutually reinforcing hydrogen bonds and π-π cooperativity in the systems.

Enantioselective neurotoxicity and oxidative stress effects of paclobutrazol in zebrafish (Danio rerio)

Paclobutrazol is a widely used chiral plant growth regulator and its enantioselective toxicity in aquatic organisms is less explored till now. Herein, the enantioselective neurotoxicity of paclobutrazol mediated by oxidative stress in zebrafish were investigated. The oxidative stress parameters and neurotoxic biomarkers changed significantly in each exposure group, and paclobutrazol showed enantioselective toxicity in zebrafish. Firstly, (2R, 3R)-paclobutrazol exhibited a stronger oxidative stress in zebrafish than (2S, 3S)-enantiomer (P < 0.05). Then, activities of acetylcholinesterase, calcineurin, and total nitric oxide synthase in (2R, 3R)-paclobutrazol treatments were 0.61-0.89, 1.24-1.53, and 1.21-1.35-fold stronger (P < 0.05) than those in (2S, 3S)-enantiomer treatments, respectively. Next, the content variations of four neurotransmitters in zebrafish exposed to (2R, 3R)-paclobutrazol were significantly larger than those in (2S, 3S)-enantiomer treatments (P < 0.05). Moreover, (2R, 3R)-paclobutrazol had stronger binding with the receptors than (2S, 3S)-enantiomer through molecular docking. The integrated biomarker response values further demonstrated that (2R, 3R)-paclobutrazol showed stronger toxicity to zebrafish than (2S, 3S)-enantiomer. Furthermore, the neurotoxicity of paclobutrazol can be interpreted as the mediating effect of oxidative stress in zebrafish through correlation analysis, and an adverse outcome pathway for the nervous system in zebrafish induced by paclobutrazol was proposed. This work will greatly extend our understanding on the enantioselective toxic effects of paclobutrazol in aquatic organisms.

Is selenium beneficial or detrimental to earthworm? Growth and metabolism responses of Eisenia Fetida to Na2SeO3 exposure

Se unevenly distributed in soils due to variations of geology and anthropogenic input, which results in different effects on earthworms. The effects of Se were characterized by analyzing the growth and metabolism responses of earthworms after exposure to three different concentrations of Na₂SeO₃. The results showed that except the possible growth promotion at 5 mg/kg, low and middle-level exposure to Na₂SeO₃ (0.3-10 mg/kg) did not significantly affect the growth of earthworms. While a significant inhibition effect on growth was observed in the high-level exposure group (30-70 mg/kg). There was an inflection point for Se performing promotion to inhibition effects on earthworm growth. To investigate the metabolic response of earthworms, a novel HPLC-ESI-MS (High Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry) method was used to determine sensitive biomarkers. Selenium exposure significantly altered the metabolism of seven essential amino acids, namely tyrosine, leucine, phenylalanine, valine, alanine, glycine, and lysine, and two selenoamino acids, namely selenomethionine and methylselenocysteine. The overall metabolism level of earthworms was not affected at low exposure concentrations, but was affected at medium and high exposure concentrations. The metabolic pathways that integrated the selenocompound metabolism and the tricarboxylic acid cycle from the perspective of energy supply and demand were affected by Na₂SeO₃ exposure. The derived reactive oxygen species at high exposure concentrations were probably the reason for the growth inhibition effect of Se on earthworms. This study provides biochemical insights into the effects of Na₂SeO₃ on earthworms and suggests that an Se concentration of about 2.3 mg/kg is appropriate for soil organism health.

Emerging impacts of ionic liquids on eco-environmental safety and human health

Owing to their unique physicochemical properties, ionic liquids (ILs) have been rapidly applied in diverse areas, such as organic synthesis, electrochemistry, analytical chemistry, functional materials, pharmaceutics, and biomedicine. The increase in the production and application of ILs has resulted in their release into aquatic and terrestrial environments. Because of their low vapor pressure, ILs cause very little pollution in the atmosphere compared to organic solvents. However, ILs are highly persistent in aquatic and terrestrial environments due to their stability, and therefore, potentially threaten the safety of eco-environments and human health. Specifically, the environmental translocation and retention of ILs, or their accumulation in organisms, are all related to their physiochemical properties, such as hydrophobicity. Based on results of ecotoxicity, cytotoxicity, and toxicity in mammalian models, the mechanisms involved in IL-induced toxicity include damage of cell membranes and induction of oxidative stress. Recently, artificial intelligence and machine learning techniques have been used in mining and modeling toxicity data to make meaningful predictions. Major future challenges are also discussed. This review will accelerate our understanding of the safety issues of ILs and serve as a guideline for the design of the next generation of ILs.

Chronic developmental exposure to low-dose ([C8mim][PF6]) induces neurotoxicity and behavioural abnormalities in rats

Ionic liquids (ILs) are widely used for their physical and chemical properties. Toxicological assessments of ILs could help to avoid their threat to human health, but these are rarely reported, and no assessments of IL neurotoxicity in mammals have been performed. Here, we aimed to evaluate the neurotoxicity of chronic 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) (0, 1 mg/kg) exposure during development on rats. Our results indicated that chronic exposure to low-dose ([C8mim][PF6]) induces behavioural abnormalities, including cognitive deficits, social communication disorders, and sensory gating function impairment. Moreover, rats subjected to chronic ([C8mim][PF6]) exposure showed hypofunction of glutamatergic excitatory synapses, including increased expression of NMDA receptor subunits, increased density and immaturity of dendritic spines, and increased expression of PSD95. Additionally, ([C8mim][PF6]) exposure resulted in hippocampal-specific inflammatory activation, indicated by increased levels of proinflammatory factors, elevated nuclear localisation of NF-κB, and activation of microglia and astrocytes. In conclusion, chronic exposure to low-dose ([C8mim][PF6]) induced neurotoxicity, including damage to glutamatergic excitatory synapses and inflammatory activation, which may illuminate the associated behavioural abnormalities. The results presented here may be helpful for the safe use of ILs in the future.

Review of the toxic effects of ionic liquids

Interest in ionic liquids (ILs), called green or designer solvents, has been increasing because of their excellent properties such as thermal stability and low vapor pressure; thus, they can replace harmful organic chemicals and help several industrial fields e.g., energy-storage materials production and biomaterial pretreatment. However, the claim that ILs are green solvents should be carefully considered from an environmental perspective. ILs, given their minimal vapor pressure, may not directly cause atmospheric pollution. However, they have the potential to cause adverse effects if leaked into the environment, for instance if they are spilled due to human mistakes or technical errors. To estimate the risks of ILs, numerous ILs have had their toxicity assessed toward several micro- and macro-organisms over the past few decades. Since the toxic effects of ILs depend on the method of estimating toxicity, it is necessary to briefly summarize and comprehensively discuss the biological effects of ILs according to their structure and toxicity testing levels. This can help simplify our understanding of the toxicity of ILs. Therefore, in this review, we discuss the key findings of toxicological information of ILs, collect some toxicity data of ILs to different species, and explain the influence of IL structure on their toxic properties. In the discussion, we estimated two different sensitivity values of toxicity testing levels depending on the experiment condition, which are theoretical magnitudes of the inherent sensitivity of toxicity testing levels in various conditions and their changes in biological response according to the change in IL structure. Finally, some perspectives, future research directions, and limitations to toxicological research of ILs, presented so far, are discussed.

Ionic Liquids-A Review of Their Toxicity to Living Organisms

Ionic liquids (ILs) were initially hailed as a green alternative to traditional solvents because of their almost non-existent vapor pressure as ecological replacement of most common volatile solvents in industrial processes for their damaging effects on the environment. It is common knowledge that they are not as green as desired, and more thought must be put into the biological consequences of their industrial use. Still, compared to the amount of research studying their physicochemical properties and potential applications in different areas, there is a scarcity of scientific papers regarding how these substances interact with different organisms. The intent of this review was to compile the information published in this area since 2015 to allow the reader to better understand how, for example, bacteria, plants, fish, etc., react to the presence of this family of liquids. In general, lipophilicity is one of the main drivers of toxicity and thus the type of cation. The anion tends to play a minor (but not negligible) role, but more research is needed since, owing to the very nature of ILs, except for the most common ones (imidazolium and ammonium-based), many of them are subject to only one or two articles.

Ecotoxicological evaluation of imazalil transformation products on Eisenia Andrei

Data concerning the toxicity of the transformation products of some pesticides considered emerging contaminants are still incipient. This study aimed to evaluate acute (filter paper contact and avoidance test) and chronic (assays carried out in Red yellow Ultisoil) effects of the transformation products of the fungicide imazalil (IMZ) by heterogeneous photocatalysis (TiO₂/UV) in Eisenia andrei. Some endpoints, i.e. biomass variation, disorder in reproduction and avoidance behavior, cytotoxicity (cell density and feasibility), and coelomic fluid (eleocytes and amoebocytes, immune cell) and antioxidant system (catalase (CAT) and glutathione S-transferase (GST)) changes were assessed. The studied degradation times (6, 18, 35 and 90 min) represented 70; 35; 10 and 0% of the initial IMZ concentration (5 mg L^-1). No lethality and no significant difference in biomass variations were noted in the acute contact test. Decreased GST and increased CAT activities, as well as cell typing alterations and decreased cell viability and density detected at the 90-min degradation timepoint (PDT-90) indicate direct cytotoxic IMZ transformation product effects. In the avoidance test, no significant earthworm repulsion or attraction was observed. PDT-90 transformation products were responsible for losses in biomass and a reduction in the number of earthworm cocoons and juveniles present in soil. No cytotoxic effects were observed in the long term, although increased CAT and decreased GST activities were observed. Investigations on the relative toxicity of IMZ transformation products are relevant for future discussions regarding the environmental treatment, control and destination of this compound and its derivatives.

Oxidative stress and DNA damage in earthworm (Eisenia fetida) induced by triflumezopyrim exposure

Triflumezopyrim is an excellent pesticide for preventing and controlling rice planthoppers. It is widely used in the production of field rice and mainly through spraying with some inadvertent loss of pesticide to the soil. The future may bring development and utilization of seeds containing triflumezopyrim which will certainly impact earthworms. To evaluate the toxic effects of triflumezopyrim on earthworms, reactive oxygen species (ROS), superoxide dismutase (SOD) and catalase (CAT) activities, malondialdehyde content (MDA), glutathione S-transferase (GST), and DNA oxidative damage (8-hydroxy-2'-deoxyguanosine, 8-OHdG) were measured after 7, 14, 21, and 28 d analyzing the effects of 6 concentrations (0, 0.5, 1, 2.5, 5 and 10 mg/kg) of triflumezopyrim, respectively. ROS content did not change significantly in the early stages but showed a significant dose-effect relationship in the late stages. Antioxidant enzymes were activated in most treatment groups, and catalase activity was the same as that in the control group at 28 d. GST activity showed a trend of increasing first and then decreasing whereas MDA content had no obvious change in trend. 8-OHdG showed significant positive correlation with the concentration of triflumezopyrim at 28 d, indicating that the degree of DNA oxidative damage increased accordingly. The results showed that chronic exposure of triflumezopyrim may cause both oxidative stress and DNA damage in earthworms and alter the activity of antioxidant enzymes.

Impact of chronic exposure to the ionic liquid ([C8mim][PF6]) on intestinal physical barrier, immunological barrier and gut microbiota in common carp (Cyprinus carpio L.)

Ionic liquids (ILs) are commonly known as "green" solvents and have been widely used in various fields. However, the ecotoxicity of ILs in aquatic environment has received considerable attention from scientific researchers. This study investigated the toxic effects of different concentrations of 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) (0, 1.35, 2.70 and 5.40 mg/L) on intestinal physical barrier, immunological barrier, and intestinal microbiome in common carp on days 30 and 60. The results showed that ([C8mim][PF6]) exposure could reduce the intestinal villus height, decrease the mRNA expression of tight junction genes (occludin, claudin-2 and zonula occludens-1), and increase the levels of D-lactic and diamine oxidase, and reduce acid phosphatase and lysozyme activities, complement 3 and 4 contents, and anti-inflammatory cytokine TGF-β protein level, while increase pro-inflammatory cytokines TNF-α and IL-1β protein levels in common carp. Moreover, ([C8mim][PF6]) exposure was also found to significantly reduce gut microbial diversity and alter microbial community structure in common carp. Collectively, our study highlighted that exposure to ([C8mim][PF6]) could disrupt intestinal physical barrier, impair immunological barrier and alter intestinal microbiome in common carp, suggesting that ILs exert a negative effect on fish intestinal health status and may pose serious health risks in fish. The results of this study may be helpful to illuminate the toxicity mechanisms of the ILs on fish.

Life stage-dependent toxicities of 1-ethyl-3-methylimidazolium bromide on Caenorhabditis elegans

Ionic liquids (ILs) are considered as extracting solvents in soil remediation. However, they can be pollutants themselves, and their own toxicities are of concerns. Notably, organisms were exposed to pollutants at random life stages in actual environmental exposure scenario, which is different from the set-up of one uniform life stage in usual experiment designs. The influence of life stages on ILs toxicities will provide essential information on their actual environmental risks. In the present study, effects of 1-ethyl-3-methylimidazolium bromide ([C₂mim]Br) were measured on C. elegans with egg exposure and adult exposure. In egg exposure, [C₂mim]Br increased the lifespan, stimulated initial reproduction and inhibited the total reproduction. Biochemical indices including oxidative stress, antioxidant responses and oxidative damage were further measured to explore the toxicity mechanisms. Results showed that [C₂mim]Br significantly stimulated O₂^-· as the oxidative stress and superoxide dismutase (SOD) as the antioxidant defense. In adult exposure, [C₂mim]Br inhibited initial reproduction, total reproduction and lifespan. Biochemical results showed that [C₂mim]Br significantly stimulated H₂O₂ and oxidized glutathione (GSSG). The overall findings demonstrated that [C₂mim]Br caused life stage-dependent toxicities on C. elegans. Future studies are still needed for the detailed mechanisms.

Acute toxicity, oxidative stress and DNA damage of chlorpyrifos to earthworms (Eisenia fetida): The difference between artificial and natural soils

Pesticides can damage the soil environment, including damage to sentinel organisms such as earthworms. When assessing the toxicity of pesticides towards earthworms, assays are usually performed using standardized artificial soil, however, soil physicochemical properties may affect pesticide toxicity. In the present study, the toxicity of a commonly used insecticide (chlorpyrifos) to earthworms (Eisenia fetida) was determined in artificial soil and three typical natural soils (fluvo-aquic soil, black soil and red clay) by measuring acute and subchronic toxicity. Soil tests were conducted to measure the acute toxicity of chlorpyrifos to Eisenia fetida quantified by the half lethal concentration (LC₅₀) while subchronic toxicity tests assessed the impact of low dose chlorpyrifos exposure (0.01, 0.1, 1 mg/kg; up to 56 d) on reactive oxygen species content, antioxidant enzymes activities, detoxifying enzyme activity, malondialdehyde content, and 8-hydroxydeoxyguanosine content. Subchronic toxicity was quantified using the integrated biomarker response (IBR) which highlighted that the toxicity of chlorpyrifos in artificial and natural soils was not the same. Outcomes from artificial soil studies may underestimate (fluvo-aquic soil and red clay) or overestimate (black soil) chlorpyrifos effects.

Acute toxicity, oxidative stress and DNA damage of three task-specific ionic liquids ([C2NH2MIm]BF4, [MOEMIm]BF4, and [HOEMIm]BF4) to zebrafish (Danio rerio)

The addition of different functional groups to ionic liquid anions or cations to synthesize task-specific ionic liquids (TSILs) according to specific needs has become a research hotspot. However, there are few studies on the toxicity of TSILs. We selected zebrafish (Danio rerio) to assess the toxicity of three TSILs 1-aminoethyl-3-methylimidazolium tetrafluoroborate ([C₂NH₂MIm]BF₄), 1-methoxyethyl-3-methylimidazolium tetrafluoroborate ([MOEMIm]BF₄) and 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate ([HOEMIm]BF₄). The 96 h median lethal concentration (96 h LC₅₀) of the three TSILs [C₂NH₂MIm]BF₄, [MOEMIm]BF₄ and [HOEMIm]BF₄ on zebrafish determined by an acute toxicity test were 143.8 mg/L, 2492.5 mg/L and 3086.7 mg/L, respectively. In the oxidative damage and DNA damage research experiments, zebrafish were exposed to [C₂NH₂MIm]BF₄ (0, 5, 10, 20 and 40 mg/L), [MOEMIm]BF₄ and [HOEMIm]BF₄ (0, 1, 10, 50 and 100 mg/L) for 28 days, and levels of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), malondialdehyde (MDA) and olive tail moment (OTM) in zebrafish liver were tested on days 7, 14, 21 and 28 after the exposure test. During the experiment, increased contents of ROS and MDA were detected; enzymatic activities especially SOD were inhibited; and DNA damage occurred in zebrafish. The toxicity of the three TSILs was compared by the integrated biomarker response (IBR). The toxicity order of three TSILs was: [MOEMIm]BF₄ > [HOEMIm]BF₄ > [C₂NH₂MIm]BF₄. In addition, this study can provide a toxicological basis for application research and the evaluation of functionalized ionic liquids with low toxicity in the future.

Evaluation of the toxicity of 1-butyl-3-methyl imidazolium tetrafluoroborate using earthworms (Eisenia fetida) in two soils

Herein, to research the toxic effect of ionic liquids (ILs) on earthworms and compare their different toxicities in different soils, 1-butyl-3-methyl imidazolium tetrafluoroborate ([Bmim]BF₄) was selected as a test substance, Eisenia fetida was selected as the experimental indicator organism, and artificial and fluvo-aquic soils were selected as the media. The acute toxicity, reactive oxygen species (ROS) content, detoxification enzyme (GST) activity, anti-oxidant enzyme activities, lipid peroxidation oxidative and DNA damage in earthworms were all measured to evaluate the toxicity of [Bmim]BF₄. The results showed that either in fluvo-aquic soil or artificial soil, [Bmim]BF₄ can stimulate the accumulation of ROS in earthworms, inducing activities of antioxidant enzymes and detoxification enzymes, inevitably causing lipid peroxidation and DNA damage in earthworms. The integrated biomarker response (IBR) indicated that the toxicity of [Bmim]BF₄ in fluvo-aquic soil was greater than that in artificial soil. This experiment is relevant to the reliability of artificial soil toxicity research, and maybe this paper can provide a more authentic understanding of traditional toxicity experiments.

Physiological responses of Chlorella pyrenoidosa to 1-hexyl-3-methyl chloride ionic liquids with different cations

Ionic liquids (ILs) are massively used in multiple fields of industry, and consequently, they have entered the environment and become potential threats to the respective ecosystems. In this paper, the toxicity of two different cationic types of ILs (1-hexyl-3-methyl pyridine chloride ([C₆Py]Cl) and 1-hexyl-3-methyl imidazole chloride ([C₆MIM]Cl)) to Chlorella pyrenoidosa (C. pyrenoidosa) was investigated. Growth inhibition increased with increasing ILs concentrations. C. pyrenoidosa showed a certain recovery at low ILs concentrations, the growth inhibition decreased from 6.13% to 1.57% of the control from 24 h to 96 h, respectively, in 0.5 mg/L [C₆MIM]Cl treatment. However, growth inhibition was negatively related with exposure time at high concentrations, and the strongest toxic effects were observed after 48 h. The IC₅₀ values (half inhibitory concentration) were 8.47, 6.65, 6.91 and 7.11 mg/L of [C₆MIM]Cl, respectively, in 24, 48, 72, and 96 h, and were 9.05, 6.83, 7.79 and 8.14 mg/L of [C₆Py]Cl, respectively. Chlorophyll content declined with higher concentrations of the ILs. The values of chlorophyll fluorescence parameters: the maximum effective quantum yield of photosystem II (PSII) (F_v/F_m), maximum quantum yield in PSII (F_v/F₀), and photosynthetic efficiency in PSII (Y(II)), decreased, whereas the minimal fluorescence (F₀) increased following the ILs treatment, indicating damage to the photosystem II. [C₆MIM]Cl and [C₆Py]Cl caused deformation of algae cells, plasmolysis, and damage of the cell membrane and cell wall, and affected organelle structure. Reactive oxygen species (ROS) concentrations increased with higher ILs concentrations from, and superoxide dismutase and catalase activity first increased and then decreased, indicating that the antioxidant defense system was activated to counteract ROS. ROS was the main stress in C. pyrenoidosa induced by ILs, and compared with [C₆Py]Cl, [C₆MIM]Cl were more toxic to C. pyrenoidosa.