Enantioselective Effects of Metalaxyl Enantiomers in Adolescent Rat Metabolic Profiles Using NMR-Based Metabolomics

Global responses to tris(1-chloro-2-propyl) phosphate and tris(2-butoxyethyl) phosphate in Escherichia coli: Evidences from biomarkers, and metabolic disturbance using GC-MS and LC-MS metabolomics analyses

Tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-butoxyethyl) phosphate (TBEP) as pollutants of emerging concern have aroused the rising attention due to their potential risks on aquatic ecosystem and public health. Nevertheless, there is a lack of toxicological mechanisms exploration of TCPP and TBEP at molecular levels. Herein, the toxicity effects and molecular mechanism of them were fully researched and summarized on Escherichia coli (E.coli). Acute exposure to them significantly activated antioxidant defense system and caused lipid peroxidation, as proved by the changes of antioxidant enzymes and MDA. The ROS overload resulted in the drop of membrane potential as well as the downregulated synthesis of ATPase, endorsing that E. coli cytotoxicity was ascribed to oxidative stress damage induced by TCPP and TBEP. The combination of GC-MS and LC-MS based metabolomics validated that TCPP and TBEP induced metabolic reprogramming in E.coli. More specifically, the responsive metabolites in carbohydrate metabolism, lipids metabolism, nucleotide metabolism, amino acid metabolism, and organic acids metabolism were significantly disturbed by TCPP and TBEP, confirming the negative effects on metabolic functions and key bioprocesses. Additionally, several biomarkers including PE(16:1(5Z)/15:0), PA(17:1(9Z)/18:2(9Z,12Z)), PE(19:1(9Z)/0:0), and LysoPE(0:0/18:1(11Z)) were remarkably upregulated, verifying that the protection of cellular membrane was conducted by regulating the expression of lipids-associated metabolites. Collectively, this work sheds new light on the potential molecular toxicity mechanism of TCPP and TBEP on aquatic organisms, and these findings using GC-MS and LC-MS metabolomics generate a fresh insight into assessing the effects of OPFRs on target and non-target aquatic organisms.

N-nitrosamines induced gender-dimorphic effects on infant rats at environmental levels

The safety of drinking water has always been a concern for people all over the world. N-nitrosamines (NAs), a kind of nitrogenous disinfection by-products (N-DBPs), are generally detected as a mixture in drinking water at home and abroad. Studies have shown that individual NAs posed strong carcinogenicity at high concentrations. However, health risks of NAs at environmental levels (concentrations in drinking water) are still unclear. Therefore, the potential health risks of environmentally relevant NAs exposure in drinking water needs to be conducted. In this study, blood biochemical analysis and metabolomics based on nuclear magnetic resonance (NMR) were performed to comprehensively investigate NAs induced metabolic disturbance in infant rats at environmental levels. Results of blood biochemical indices analysis indicated that AST in the serum of male rats in NAs-treated group exhibited a significant gender-specific difference. Multivariate statistics showed that two and eight significantly disturbed metabolic pathways were identified in the serum samples of NAs-treated male and female rats, respectively. In the urine samples of NAs-treated female rats, glycine, serine, and threonine metabolism pathway was significantly disturbed; while three significantly disturbed metabolic pathways were found in the urine of NAs-treated male rats. Finally, results of spearman correlation coefficients suggested that the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota (data derived from our published paper). Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management. ENVIRONMENTAL IMPLICATION: N-nitrosamines (NAs) are a kind of nitrogenous disinfection by-products (N-DBPs) generated during drinking water disinfection processes. Herein, health risks of NAs at environmental levels (concentrations in drinking water) are investigated using blood biochemical analysis and nuclear magnetic resonance (NMR)-based metabolomics. Results confirmed NAs induced gender-specific on the metabolism in rat and the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota. Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management.

Enantiomer-specific burden of metalaxyl and myclobutanil in non-occupationally exposed population with evidence from dietary intake and urinary excretion

Metalaxyl (MET) and myclobutanil (MYC) are two widely used chiral fungicides that may pose health risks to non-occupationally exposed populations. Here, the two fungicides were enantiomer-specific quantified in the dietary food and urine of residents in an Eastern China city, to determine the exposure and excretion of these contaminants in different populations. Results indicate that residues of MET and MYC varied with different food items at 0.42-0.86 ng/g fresh weight (FW) and 0.18-0.33 ng/g FW, respectively. In urine samples, the residual levels after creatinine adjusting (CR) ranged from 10.2 to 1715.4 ng/g CR for MET and were below the detection limit up to 320.7 ng/g CR for MYC. Significant age- and gender-related differences were separately found in urinary MET and MYC of different populations. Monte-Carlo simulations suggested that children had higher daily dietary intake (DDI) but lower urinary excretion (DUE) rates than youths, and thus may suffer higher body burdens. The residues of antifungally ineffective enantiomers (S-MET and R-MYC) were slightly higher than their antipodes in foods. Moreover, the enantiomer-selective urinary excretion resulted in higher retention of S-MET and R-MYC in the human body. Our results suggest that both dietary intake and urinary excretion should be enantiomer-specifically considered when assessing the exposure risk and body burden of chiral fungicides in the non-occupationally exposed population. Furthermore, substitutive application of enantiomer-enriched fungicide formulations can not only benefit the antifungal efficacy but also be safer for human health.

The toxic mechanism of 6:2 Cl-PFESA in adolescent male rats: Endocrine disorders and liver inflammation regulated by the gut microbiota-gut-testis/liver axis

In previous studies, 6:2 chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA), a perfluorooctanesulfonate alternative, has been demonstrated to be toxic to mammals. However, the toxic mechanism of 6:2 Cl-PFESA in mammals is unknown. Herein, adolescent male rats were administered 50 μg/kg/Day 6:2 Cl-PFESA for 28 days (oral gavage) to estimate the toxicity of 6:2 Cl-PFESA and investigate its toxic mechanism. Significant changes in some hematological indicators (e.g., aspartate transaminase and neutrophils) and liver sections (inflammatory cell infiltration) indicated that 6:2 Cl-PFESA exposure caused rat hepatotoxicity. Six steroid hormones (e.g., testosterone, progesterone, and cortisol) in serum and thirteen genes in testicles (related to the pathway of steroid hormone biosynthesis) were significantly regulated in 6:2 Cl-PFESA-treated rats. This suggested that 6:2 Cl-PFESA induced rat endocrine disorders. Compared to the controls, the mean relative abundance of Ruminococcaceae, Pasteurellaceae, Micrococcaceae, and Desulfovibrionaceae was significantly regulated by 1.3-, 0.40-, 0.32-, and 3.2-fold in the 6:2 Cl-PFESA rats, respectively. The 6:2 Cl-PFESA treatment also significantly disturbed 47 gut metabolites (29 upregulated and 18 downregulated), mainly bile acids, short-chain fatty acids, and amino acids. In summary, 6:2 Cl-PFESA induced endocrine disorders and liver inflammation in rats by altering the gut microbiota-gut-testis/liver axis. This study first reveals the toxic mechanism of 6:2 Cl-PFESA in mammals through a multiomics approach and provides comprehensive insight into the toxic mechanism of 6:2 Cl-PFESA.

The concentration of pesticides in tomato: a global systematic review, meta-analysis, and health risk assessment

To improve farming productivity, a large number of pesticides have been used worldwide in recent decades, leading to the pollution of soil, agri-products, and water, directly/indirectly affecting human health. In this regard, many studies were conducted in different countries on residual pesticides in the environment. In the current study, residual pesticides including chlorpyrifos, cypermethrin, diazinon, malathion, and metalaxyl in tomatoes were meta-analyzed and health risk of consumers was estimated. For this purpose, based on a systematic review, data from 47 studies were extracted and meta-analyzed, and the health impact of pooled concentrations was assessed via a health risk method. According to the results, metalaxyl had the most concentration followed by malathion, cypermethrin, diazinon, and chlorpyrifos, respectively. The non-carcinogenic risk (n-CR) was calculated from crop consumption also showed that exposure to malathion has the most risk. Among the investigated communities, Iranian consumers were in considerable health risk (THQ > 1). Considering that the potential for the use of pesticides will increase with the need for food in the future, hence, governments must manage the usage by governments via alternative methods such as cultural, biological, physical, and genetic modifications.

Enantioselectivity in the toxicological effects of chiral pesticides: A review

As a special category of pesticides, chiral pesticides have increased the difficulty in investigating pesticide toxicity. Based on their usage, chiral pesticides can be divided into insecticides, herbicides, and fungicides. Over the past decades, great efforts have been made on elucidating their toxicological effects. However, no literature has reviewed the enantioselective toxicity of chiral pesticides since 2014. In recent years, more chiral pesticides have been registered for application. As such, huge research progresses have been achieved in enantioselective toxicity of chiral pesticides. Generally, more researches have remedied the knowledge gap in toxicological effects of old and new chiral pesticides. And the toxicological endpoints being evaluated have become more specific rather than centering on basic toxicity and target organisms. Besides, the underlying mechanisms accounting for the enantioselectivity in toxicological effects of chiral pesticides have been discussed as well. All in all, this review provides the critical knowledge for risk assessments, and help to drive the green-technology of single- or enriched-enantiomer pesticides and formulation of relevant laws and regulations.

Systematic evaluation of chiral pesticides at the enantiomeric level: A new strategy for the development of highly effective and less harmful pesticides

Over the past few decades, pesticides have been used in large quantities, and they pose potential risks to organisms across various environments. Reducing the use of pesticides and their environmental risks has been an active research focus and difficult issue worldwide. As a class of pesticides with special structures, chiral pesticides generally exhibit enantioselectivity differences in biological activity, ecotoxicity, and environmental behavior. At present, replacing the racemates of chiral pesticides by identifying and developing their individual enantiomers with high efficiency and environmentally friendly characteristics is an effective strategy to reduce the use of pesticides and their environmental risks. In this study, we review the stereoselective behaviors of chiral pesticide, including their environmental behavior, stereoselective biological activity, and ecotoxicity. In addition, we emphasize that the systematic evaluation of chiral pesticides at the enantiomeric level is a promising novel strategy for developing highly effective and less harmful pesticides, which will provide important data support and an empirical basis for reducing pesticide application.

Toxicity effects of chlorantraniliprole in zebrafish (Danio rerio) involving in liver function and metabolic phenotype

Chlorantraniliprole (CAP), a representative bisamide insecticide, is widely used in rice fields around the world, posing potential toxicity risks to aquatic organisms. In this study, we examined the effects of exposure to CAP on growth and metabolic phenotype of zebrafish (Danio rerio) and oxidative stress and apoptosis in the liver of zebrafish (Danio rerio). First, we identified that CAP had a low bioaccumulation in zebrafish. Subsequently, growth phenotype analysis revealed that CAP could significantly increase liver weight and liver index in zebrafish. In addition, we found that CAP exposure could cause significant changes in indicators of oxidative stress, resulting in a significant increase in the content of malondialdehyde (MDA), causing oxidative stress in the liver of zebrafish. Meanwhile, the expression levels of apoptosis-related genes were also significantly changed and apoptosis was promoted in the liver of zebrafish with CAP exposure. Importantly, the results of metabolomics analysis shown that CAP exposure could significantly disrupt the metabolic phenotype of zebrafish, interfering with multiple metabolic pathways, mainly including valine, leucine and isoleucine biosynthesis and degradation, alanine, aspartate and glutamate metabolism and d-glutamine and D-glutamate metabolism. Last but not least, correlation analysis identified strong links between changes in liver function involving oxidative stress and apoptosis and changes in metabolic phenotype of zebrafish following CAP exposure. In brief, these results indicate that potential environmental risks of CAP to aquatic organisms should receive more attention.

Triticonazole enantiomers induced enantioselective metabolic phenotypes in Fusarium graminearum and HepG2 cells

The management of Fusarium head blight relies heavily on triazole fungicides. Most of triazole fungicides are chiral, and their enantioselective effects on metabolic phenotypes are poorly understood. Herein, we analyzed the bioactivity of triticonazole against Fusarium graminearum, and ¹H-nuclear magnetic resonance-based metabolomics was used to assess the metabolic disturbances of triticonazole enantiomers in Fusarium graminearum and human hepatocarcinoma cells. Results indicated that the bioactivity of R-triticonazole was 4.28-fold higher than its antipode since it bound stronger with fungal CYP51B and induced more abnormal metabolic processes of Fusarium graminearum, including lipid metabolism, glycolysis, and amino acid metabolism. In human hepatocarcinoma cells, pathways of "alanine, aspartic acid and glutamate metabolism" and "pyruvate metabolism" were disturbed significantly by R-triticonazole; "phenylalanine metabolism" and "taurine-hypotaurine metabolism" were abnormal in the exposure of S-triticonazole. These results suggested that R- and S-triticonazole could affect different metabolic pathways of human hepatocarcinoma cells, and the massively use of inefficient S-triticonazole should be avoided. Our data will help to better understand the enantioselectivity of chiral pesticides and provide a reference for the development of green pesticides.

Study on toxicity effects of environmental pollutants based on metabolomics: A review

In the past few decades, the toxic effects of environmental pollutants on non-target organisms have received more and more attention. As a new omics technology, metabolomics can clarify the metabolic homeostasis of the organism at the overall level by studying the changes in the relative contents of endogenous metabolites in the organism. Recently, a large number of studies have used metabolomics technology to study the toxic effects of environmental pollutants on organisms. In this review, we reviewed the analysis processes and data processes of metabolomics and its application in the study of the toxic effects of environmental pollutants including heavy metals, pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers and microplastics. In addition, we emphasized that the combination of metabolomics and other omics technologies will help to explore the toxic mechanism of environmental pollutants and provide new research ideas for the toxicological evaluation of environmental pollutants.

Developments in the Catalytic Asymmetric Synthesis of Agrochemicals and Their Synthetic Importance

Catalytic asymmetric synthesis has become an essential tool for the enantioselective synthesis of pharmaceuticals, natural products, and agrochemicals (mainly fungicides, herbicides, insecticides, and pheromones). With continuous growing interest in both modern agricultural chemistry and catalytic asymmetric synthesis chemistry, this review provides a comprehensive overview of some earlier reports as well as the recent successful applications of various catalytic asymmetric syntheses methodologies, such as enantioselective hydroformylation, enantioselective hydrogenation, asymmetric Sharpless epoxidation and dihydroxylation, asymmetric cyclopropanation or isomerization, organocatalyzed asymmetric synthesis, and so forth, which have been used as key steps in the preparation of chiral agrochemicals (on R&D, piloting, and commercial scales). Chiral agrochemicals can also lead the new generation of such chemicals having specific and novel modes of action for achieving sustainable crop protection and production. Some perspectives and challenges for these catalytic asymmetric methodologies in the synthesis of chiral agrochemicals are also briefly discussed in the final section of the manuscript. This review will provide the insight regarding understanding, development, and evaluation of catalytic asymmetric systems for the synthesis of chiral agrochemicals among the agrochemists.

Old pesticide, new use: Smart and safe enantiomer of isocarbophos in locust control

Locust plagues are still worldwide problems. Selecting active enantiomers from current chiral insecticides is necessary for controlling locusts and mitigating the pesticide pollution in agricultural lands. Herein, two enantiomers of isocarbophos (ICP) were separated and the enantioselectivity in insecticidal activity against the pest Locusta migratoria manilensis (L. migratoria) and mechanisms were investigated. The significant difference of LD₅₀ between (+)-ICP (0.609 mg/kg bw) and (-)-ICP (79.412 mg/kg bw) demonstrated that (+)-ICP was a more effective enantiomer. The enantioselectivity in insecticidal activity of ICP enantiomers could be attributed to the selective affinity to acetylcholinesterase (AChE). Results of in vivo and in vitro assays suggested that AChE was more sensitive to (+)-ICP. In addition, molecular docking showed that the -CDOKER energies of (+)-ICP and (-)-ICP were 25.6652 and 24.4169, respectively, which suggested a stronger affinity between (+)-ICP and AChE. Significant selectivity also occurred in detoxifying enzymes activities (carboxylesterases (CarEs) and glutathione S-transferases (GSTs)) and related gene expressions. Suppression of detoxifying enzymes activities with (+)-ICP treatment suggested that (-)-ICP may induce the detoxifying enzyme-mediated ICP resistance. A more comprehensive understanding of the enantioselectivity of ICP is necessary for improving regulation and risk assessment of ICP.

Glycine-Serine-Threonine Metabolic Axis Delays Intervertebral Disc Degeneration through Antioxidant Effects: An Imaging and Metabonomics Study

Although intervertebral disc degeneration (IDD) can be described as different stages of change through biological methods, this long and complex process cannot be defined in stages by single or simple combination of biological techniques. Under the background of the development of nuclear magnetic resonance (NMR) technology and the emerging metabonomics, we based on animal models and expanded to the study of clinical human degeneration models. The characteristics of different stages of IDD were analyzed by omics. Omics imaging combined with histology, cytology, and proteomics was used for screening of the intervertebral disc (IVD) of research subjects. Furthermore, mass spectrometry nontargeted metabolomics was used to explore profile of metabolites at different stages of the IDD process, to determine differential metabolic pathways and metabolites. NMR spectroscopy was used to qualitatively and quantitatively identify markers of degeneration. NMR was combined with mass spectrometry metabolomics to explore metabolic pathways. Metabolic pathways were determined through protein molecular biology and histocytology of the different groups. Distinguishing advantages of magnetic resonance spectroscopy (MRS) for analysis of metabolites and effective reflection of structural integrity and water molecule metabolism through diffusion tensor imaging (DTI) were further used to verify the macrometabolism profile during degeneration. A corresponding model of in vitro metabolomics and in vivo omics imaging was established. The findings of this study show that a series of metabolic pathways associated with the glycine-serine-threonine (Gly-Ser-Thr) metabolic axis affects carbohydrate patterns and energy utilization efficiency and ultimately delays disc degeneration through antioxidant effects.

Evaluation of the cytotoxic and genotoxic potential of the captan-based fungicides, chlorothalonil-based fungicides and methyl thiophanate-based fungicides in human fibroblasts BJ

The objectives of this study were to examine cytotoxic and genotoxic damage in human BJ fibroblasts caused by three pesticides used worldwide by trypan blue dye exclusion assays and to measure the relative level of phosphorylated histone H2A.X by flow cytometry at different concentrations. Captan-based fungicide and methyl thiophanate-based fungicide (100 and 1000 µΜ) showed immediate cytotoxic effects; furthermore, after 24 h, captan-based fungicide, chlorothalonil-based fungicide and methyl thiophanate-based fungicide caused cytotoxic effects in the concentration ranges of 40-100 µM, 30-100 µM and 150-1000 µM, respectively. All fungicides generated DNA damage in the treated cells by activating ATM and H2A.X sensor proteins. The three fungicides tested generated DNA double-stranded breaks and showed cytotoxicity at concentrations 33, 34, and 5 times lower (captan, chlorothalonil and thiophanate-methyl respectively) than those used in the field, as recommended by the manufacturers.

Systematic investigation of stereochemistry, stereoselective bioactivity, and antifungal mechanism of chiral triazole fungicide metconazole

In this study, the stereochemistry, stereoselective fungicidal bioactivity, and antifungal mechanism of chiral triazole fungicide metconazole were investigated. The configurations of metconazole stereoisomers were determined to be (1R, 5R)-metconazole, (1R, 5S)-metconazole, (1S, 5S)-metconazole, and (1S, 5R)-metconazole through using electronic circular dichroism spectroscopy. The bioactivities of four stereoisomers and their stereoisomer mixture toward Fusarium graminearum Schw and Alternaria triticina were found to be in the following order: (1S, 5R)-metconazole > the stereoisomer mixture > (1S, 5S)-metconazole > (1R, 5R)-metconazole > (1R, 5S)-metconazole. In addition, the fungicidal activities of (1S, 5R)-metconazole against two tested pathogens was 13.9-23.4 times higher than those of (1R, 5S)-metconazole. Molecular docking methodology was applied to characterize the docking energy and distances between Cytochrome P450 CYP51B and the metconazole stereoisomers, and (1S, 5R)-metconazole showed the strongest binding energy and the shortest distance binding to CYP51B than the other three stereoisomers. Moreover, enantioselective metabolisms of (1S, 5R)-metconazole and (1R, 5S)-metconazole by Fusarium graminearum Schw were investigated through NMR-based metabolomics. The amounts of alanine, arginine, acetate, ethanol, and dimethylamine produced in the presence of (1R, 5S)-metconazole were significantly higher than corresponding amounts in the presence of (1S, 5R)-metconazole, whereas the amounts of glucose, glycerol, glutamate, methionine, and trimethylamine formed in the presence of (1R, 5S)-metconazole were much less than those in the presence of (1S, 5R)-metconazole. This systematic investigation of metconazole stereoisomers would provide a new perception of metconazole in stereoisomeric level, including bioactivities, metabolic behaviors and antifungal mechanism.

Effects of Dufulin on Oxidative Stress and Metabolomic Profile of Tubifex

Dufulin is a highly effective antiviral pesticide used in plants. In this study, a seven-day experiment was conducted to evaluate the effects of Dufulin at five different concentrations (1 × 10⁻⁴, 1 × 10⁻³, 1 × 10⁻², 0.1, and 1 mg/L) on Tubifex. LC-MS-based metabolome analysis detected a total of 5356 features in positive and 9110 features in negative, of which 41 showed significant changes and were identified as differential metabolites. Four metabolic pathways were selected for further study. Detailed analysis revealed that Dufulin exposure affected the urea cycle of Tubifex, probably via argininosuccinate lyase (ASL) inhibition. It also affected the fatty acid metabolism, leading to changes in the concentration of free fatty acids in Tubifex. Furthermore, the changes in metabolites after exposure to Dufulin at 1 × 10⁻² mg/L were different from those at the other concentrations.

Changes in soil and rat gut microbial diversity after long-term exposure to the chiral fungicide epoxiconazole

In previous articles, it was found that epoxiconazole enantiomers can persist for a long time in the environment, causing severe environmental damage. Herein, we investigated alterations in the soil microbial community and rat gut microbiota after six weeks of treatment with rac-epoxiconazole or one of its enantiomers. The selected concentrations were 1, 2, and 6 times greater than the maximum residue limits (MRLs). The rat gut microbiota relative abundance in the feces significantly changed following exposure to rac-epoxiconazole or one of its enantiomers. At the phylum level, in the R,S-, S,R-epoxiconazole, and rac-treated groups, Firmicutes presented the greatest decrease in abundance; however, Spirochaetes presented the greatest increase in abundance in the rac- and S,R-epoxiconazole-treated groups. In response to R,S-epoxiconazole, Epsilonbacteraeota presented the greatest increase in abundance. In soil samples treated with epoxiconazole, the relative abundance of the soil bacterial community also changed. Proteobacteria presented the greatest decrease in abundance in the S,R- and rac-treated samples. However, Firmicutes presented the greatest increase in abundance. In the R,S-treated soil samples, the situation was the opposite. In general, prolonged exposure to epoxiconazole at high concentrations could initiate noticeable alterations in rat gut microbiota and soil microbial diversity. R,S-epoxiconazole had improved bioactivity and less toxic effects at relatively low concentrations. Therefore, we recommend using R,S-epoxiconazole at a relatively low concentration, which is better for environmental safety.

Supercritical fluid chromatography-mass spectrometric determination of chiral fungicides in viticulture-related samples

Supercritical fluid chromatography (SFC), combined with mass spectrometry (MS), was employed for the determination of five chiral fungicides, from two different chemical families (acylalanine and triazol) in wine and vineyard soils. The effect of different SFC parameters (stationary phase, chiral selector, mobile phase modifier and additive) in the resolution between enantiomers and in the efficiency of compounds ionization at the electrospray source (ESI) was thorougly described. Under final working conditions, chiral separations of selected fungicides were achieved using two different SFC-MS methods, with an analysis time of 10 min and resolution factors from 1.05 to 2.45 between enantiomers. In combination with solid-phase extraction and pressurized liquid extraction, they permitted the enantiomeric determination of target compounds in wine and vineyard soils with limits of quantification in the low ppb range (between 0.5 and 2.5 ng mL^-1, and from 1.3 to 6.5 ng g^-1, for wine and soil, respectively), and overall recoveries above 80%, calculated using solvent-based standards. For azolic fungicides (tebuconazole, myclobutanil and penconazole) soil dissipation and transfer from vines to wines were non-enantioselective processes. Data obtained for acylalanine compounds confirmed the application of metalaxyl (MET) to vines as racemate and as the R-enantiomer. The enantiomeric fractions (MET-S/(MET-S+MET-R)) of this fungicide in vineyard soils varied from 0.01 to 0.96; moreover, laboratory degradation experiments showed that the relative dissipation rates of MET enantiomers varied depending on the type of soil.

Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for decades. Metabolomics, a functional readout of cellular activity, can capture organismal responses to various contaminant-related stressors, acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants better. This review entails the application of metabolomics to profile metabolic responses of environmental organisms, e.g. animals (rodents, fish, crustacean and earthworms) and microorganisms (bacteria, yeast and microalgae) to different anthropogenic contaminants, including heavy metals, nanomaterials, pesticides, pharmaceutical and personal products, persistent organic pollutants, and assesses their ecotoxicological impacts with regard to literature published in the recent five years. Contaminant-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical organisms. The obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living organisms. Thus with a novel ecotechnique of environmental metabolomics, risk assessments of anthropogenic contaminants are profoundly demonstrated.

Using a network of lower-cost monitors to identify the influence of modifiable factors driving spatial patterns in fine particulate matter concentrations in an urban environment

BACKGROUND

There is substantial interest in using networks of lower-cost air quality sensors to characterize urban population exposure to fine particulate matter mass (PM_2.5). However, sensor uncertainty is a concern with these monitors.

OBJECTIVES

(1) Quantify the uncertainty of lower-cost PM_2.5 sensors; (2) Use the high spatiotemporal resolution of a lower-cost sensor network to quantify the contribution of different modifiable and non-modifiable factors to urban PM_2.5.

METHODS

A network of 64 lower-cost monitors was deployed across Pittsburgh, PA, USA. Measurement and sampling uncertainties were quantified by comparison to local reference monitors. Data were sorted by land-use characteristics, time of day, and wind direction.

RESULTS

Careful calibration, temporal averaging, and reference site corrections reduced sensor uncertainty to 1 μg/m³, ~10% of typical long-term average PM_2.5 concentrations in Pittsburgh. Episodic and long-term enhancements to urban PM_2.5 due to a nearby large metallurgical coke manufacturing facility were 1.6 ± 0.36 μg/m³ and 0.3 ± 0.2 μg/m³, respectively. Daytime land-use regression models identified restaurants as an important local contributor to urban PM_2.5. PM_2.5 above EPA and WHO daily health standards was observed at several sites across the city.

SIGNIFICANCE

With proper management, a large network of lower-cost sensors can identify statistically significant trends and factors in urban exposure.

Enantioselectivity effects of imazethapyr enantiomers to metabolic responses in mice

Imazethapyr (IMZT) is a typical chiral pesticide with two enantiomers with the R-IMZT having the main herbicidal activity. However, the enantioselectivity of the effects of IMZT enantiomers on human and animals is still unclear. In this study, a nuclear magnetic resonance (NMR)-based metabolomics method and determination of oxidative stress were used to evaluate the enantioselectivity of IMZT enantiomers in mice. The results showed that the R-IMZT caused larger disturbances of endogenous metabolites and the S-IMZT had stronger interferences to oxidation defense system. The significantly perturbed metabolic pathways in mice exposed to the R-enantiomer were the valine, leucine and isoleucine biosynthesis pathway as well as the phenylalanine, tyrosine and tryptophan biosynthesis pathway. However, exposure of mice to the S-enantiomer did not significantly affect the metabolic pathways, but exposure led to an increase of catalase (CAT) activity and an increase in malondialdehyde (MDA) content in the liver. These results indicate that we need to conduct a more comprehensive assessment of the health risks of pesticide monomers in the future. In a word, these results provide more evidence for assessing the differences in health risks of IMZT enantiomers to mammals as well as provide more references for the promotion and use of pesticide monomers in the future.

Four cypermethrin isomers induced stereoselective metabolism in H295R cells

Cypermethrin (CP) is widely used for controlling agricultural and indoor vermin. Previous studies have reported the stereoselective difference of CP in biological activities. However, little is known about their potential mechanisms between metabolic phenotypes and endocrine-disrupting effects. Herein, nuclear magnetic resonance (NMR)-based metabolomics combining metabolite identification and pathway analysis were applied to evaluate the stereoselective metabolic cdisorders induced by CP isomers in human adrenocortical carcinoma cells (H295R) culture medium. Then, gene expression levels related to disturbed metabolic pathways were assessed to verify according to metabolic phenotypes. Metabolomics profiles showed that [(S)-cyano(3-phenoxyphenyl)methyl](1R,3R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate [(1R,3R,αS)-CP] induced the most significant changes in metabolic phenotypes than did the other stereoisomers. There are 10 differential metabolites (isoleucine, valine, leucine, ethanol, alanine, acetate, aspartate, arginine, lactate, and glucose) as well as two significantly disturbed pathways, including "pyruvate metabolism" and "alanine, aspartate, and glutamate metabolism," that were confirmed in H295R cells culture medium of (1R,3R,αS)-CP compared with other stereoisomers. Polymerase chain reaction (PCR) array also confirmed the results of metabolomics. Our results can help to understand the potential mechanisms between the isomer selectivity in metabolic phenotypes and endocrine-disrupting effects. Data provided here not only lend authenticity to the cautions issued by the scientists and researchers but also offer a solution for the balance between environment and political regulations.

Neonicotinoid insecticides exposure cause amino acid metabolism disorders, lipid accumulation and oxidative stress in ICR mice

Neonicotinoids are increasingly being used for pest control, and their potential health risks are now receiving attention. In this study, the toxic effects of three neonicotinoids (dinotefuran, nitenpyram and acetamiprid) were evaluated in ICR mice. After 30 days of exposure to neonicotinoids (1/200 LD50), oxidative stress levels, biochemical parameters, free fatty acids contents, and ¹H NMR-based hepatic metabolomics were tested. All treatment groups showed signs of amino acid metabolism disorders especially elevated branched chain amino acids and phenylalanine. Furthermore, animals exposed to neonicotinoids had elevated lipid levels, which induced oxidative stress. Overall, we found that oxidative stress is a common toxic effect of exposure to neonicotinoids. In addition, lipid accumulation induced by amino acid metabolism disorder may be the cause of oxidative stress. Our results further our understanding of the toxicological effects of neonicotinoids on mammals.

Metabolic profiling of liver tissues in mice after instillation of fine particulate matter

Human exposure to fine particulate matter (PM_2.5) in various environment could lead to a number of adverse health effects. Little is known about the toxic mechanism and the further response caused by PM_2.5 exposure. In this study, a metabolomics approach using gas chromatography-mass spectrometry (GC-MS) was adopted to evaluate the liver toxicity induced by different gradient concentrations of PM_2.5. A multivariate statistical analysis had shown, a total of 12 endogenous metabolites including amino acids and organic acids were identified as potential biomarkers of PM_2.5 and most of them were down-regulated. By analyzing the metabolic pathways using the identified biomarkers, the significantly interfered metabolic pathways when mice were exposed to PM_2.5 were found as: glycine, serine and threonine metabolism, aminoacyl-tRNA biosynthesis, cysteine and methionine metabolism, alanine, aspartate and glutamate metabolism, methane metabolism, linoleic acid metabolism and valine, and leucine and isoleucine biosynthesis, all of which were closely related to liver metabolism. The findings of this study reveal detailed toxic metabolic effects of PM_2.5 in liver tissues, provide ways for assessing the health risk of PM_2.5 at molecular level, and further offer insights on the potential mechanism of its toxicity.

Identifying Metabolic Perturbations and Toxic Effects of Rac-Metalaxyl and Metalaxyl-M in Mice Using Integrative NMR and UPLC-MS/MS Based Metabolomics

Although metabolic perturbations are sensitive indicators for low-dose toxic effects, the metabolic mechanisms affected by rac-metalaxyl and metalaxyl-M in mammals from a metabolic profiling perspective remain unclear. In this study, the metabolic perturbations and toxic effects of rac-metalaxyl and metalaxyl-M in mice were carefully investigated using integrative nuclear magnetic resonance (NMR) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based metabolomics. Histopathology, NMR-based untargeted urine profile, multivariate pattern recognition, metabolite identification, pathway analysis, UPLC-MS/MS based targeted serum amino acids, and tryptophan pathway analysis were determined after rac-metalaxyl and metalaxyl-M exposure, individually. Histopathology indicated that metalaxyl-M induced greater hepatocellular inflammatory, necrosis, and vacuolation in mice than rac-metalaxyl at the same exposure dosage. The metabolic perturbations induced by rac-metalaxyl and metalaxyl-M were directly separated using partial least-squares discriminant analysis (PLS-DA). Furthermore, metabolite identification and pathway analysis indicated that rac-metalaxyl mainly induced ten urine metabolite changes and four pathway fluctuations. However, metalaxyl-M induced 19 urine metabolite changes and six pathway fluctuations. Serum amino acids and tryptophan pathway metabolite changes induced by rac-metalaxyl and metalaxyl-M were also different even at the same exposure level. Such results may provide specific insight into the metabolic perturbations and toxic effects of rac-metalaxyl and metalaxyl-M, and contribute to providing available data for health risk assessments of rac-metalaxyl and metalaxyl-M at a metabolomics level.

Nonstereoselective foliar absorption and translocation of cycloxaprid, a novel chiral neonicotinoid, in Chinese cabbage

Exploring traditional neonicotinoid pesticides substitutes has become one of the global scientific attentions because of their hazardous environmental impacts. Cycloxaprid (CYC) is considered to be a promising candidate alternative. But the environmental behaviors and fate of CYC in different planting system remain poorly understood. The accumulation of ¹⁴C-labeled CYC stereoisomers within different parts of Chinese cabbage (Brassica chinensis L.) was investigated, with a particular focus on the foliar absorption, translocation and stereoselectivity of CYC, during a laboratory trial. In general, the stereoisomers ¹⁴C-5R,8S-CYC and ¹⁴C-5S,8R-CYC, their metabolites, as well as the breakdown and reaction products can be transferred in both acropetal and basipetal directions. Most of the two stereoisomers absorbed by plants remained in the treated leaves, whereas a small amount was distributed to the roots. The amount of ¹⁴C in the stalks varied among the experimental time points. At 192 h after treatment (HAT), the detected radioactivity of both ¹⁴C-5R,8S-CYC and ¹⁴C-5S,8R-CYC in the leaves above the treated leaf (LATL) was higher than that in the leaves below the treated leaf (LBTL). However, the stereoisomers of CYC underwent nonstereoselective absorption and translocation in this trial. This information implies that racemic CYC and its metabolites should be a main research focus. Thus, the obtained results provide implications for a more accurate prediction about the risk assessment of CYC, which will be helpful for guiding its rational use as well as securing the ecological environment safety and human health.

Metabolomic modulations of HepG2 cells exposed to bisphenol analogues

Bisphenol analogues including bisphenol A (BPA), bisphenol AF (BPAF), bisphenol F (BPF), and bisphenol S (BPS) share similar chemical structures and endocrine disrupting effects. Their effects on metabolisms, however, are so far only marginally understood. In this study, NMR-based metabonomic profiles of HepG2 cell culture media and PCR array were used to assess the metabolomics disturbances and gene expression levels of HepG2 in response to four BPs (BPA, BPAF, BPF, and BPS). The results indicated that BP analogues resulted in disturbances in 7-15 metabolites that were classified as amino acid (alanine, glutamine, glutamate), intermediates and end-products in the glycolysis (pyruvate) and the tricarboxylic acid cycle (acetate, lactate). Their rank in order according to the number of metabolites and pathways was BPF > BPA > BPAF > BPS. The common disrupted pathways (pyruvate metabolism; alanine, aspartate, and glutamate metabolism) indicated enhanced glycolysis. The following glucometabolic PCR array analysis suggested that although four BPs shared the capability of disrupting glucose metabolism, they may act through different mechanisms: BPAF has increased the pyruvate kinase (PKLR) expression level, which implied enhanced glycolysis that was agreed with NMR results. The other three BP analogues, however, decreased the expression level of glucokinase (GCK) that indicated glucose sensing impairment. Our results demonstrated the potential for using metabolomic and PCR array to understand the underlying action of mechanisms and identify the potential targets for future targeted risk assessment.

Impacts of Penconazole and Its Enantiomers Exposure on Gut Microbiota and Metabolic Profiles in Mice

Exposure to chiral pesticides poses many potential health risks. In this study, we examined the impacts of exposure to penconazole and its enantiomers on gut microbiota and metabolic profiles in mice. The relative abundance of microbiota in cecal content significantly changed following exposure to penconazole and its enantiomers. At the genus level, the relative abundances of seven gut microflora were altered following exposure to (-)-penconazole. Both (±)-penconazole and (+)-penconazole caused significant changes in the relative abundances of five gut microflora. In addition, targeted serum metabolomics analysis showed disturbed metabolic profiles following exposure. Respectively, (±)-penconazole, (+)-penconazole, and (-)-penconazole exposure significantly altered the relative levels of 29, 23, and 36 metabolites. In general, exposure to penconazole and its enantiomers caused disorders in gut microbiota and metabolic profiles of mice. The potential health risks of penconazole and its enantiomers now require further evaluation.

Analysis of metabolome changes in the HepG2 cells of apatinib treatment by using the NMR-based metabolomics

Neovascularization is required for the growth of tumors, vascular endothelial growth factor (VEGF) and related signal pathways are important in tumor angiogenesis. Apatinib is a highly selective and potent antiangiogenesis drug targeting the receptor of VEGFR2, blocking downstream signal transduction and inhibiting angiogenesis of tumor tissue. Apatinib has a wide range of antitumor activities in vitro and in vivo, but its effect on metabolic changes has not deeply research at present. Nowadays, our research first systematically studied the metabolic changes affected by apatinib in the HepG2 cells at the half-maximal inhibitory concentration value. We used the metabolomics by using ¹ H nuclear magnetic resonance (¹ H-NMR) to analyze the HepG2 cell culture media. Multivariable Statistics was applied to analyze the ¹ H-NMR spectra of the cell media, including principal component analysis, partial least squares discriminant analysis (PLS-DA) and orthogonal PLS-DA (OPLS-DA). Compared with the uncultured and cultured media (negative/positive control), the metabolic phenotypes were changed in the apatinib treatment with a continuous effect over time. The metabolic pathway analysis is shown that the mainly disturbed metabolic pathways pyruvate metabolism, alanine, aspartate, and glutamate metabolism and amino acid metabolism associated with them in the apatinib treatment. The differential metabolites which were identified from the reconstructed OPLS-DA loading plots also reflected in these disturbed metabolic pathways. Our works could allow us to well understand the therapeutic effect of apatinib, especially in metabolism.

1H NMR-based metabolomic analysis of nine organophosphate flame retardants metabolic disturbance in Hep G2 cell line

Organophosphate flame retardants (OPFRs) are frequently found in the environment and could be adversely affecting organisms. In fact, nine OPFRs have been shown to cause endocrine disruptions, but information on the metabolism-perturbing properties of these OPFRs remains unclear. In this study, the ¹H-nuclear magnetic resonance (NMR) based metabolomic method was applied to evaluate the metabolic disturbances caused by these nine OPFRs. From the analysis of the metabolic phenotypes, we found that TDBPP, TMPP and TPHP could be clustered into one group; TBOEP, TCIPP, TCEP and TEHP could be clustered into another group; and the residual OPFRs could be clustered into another. The classification results agree with the antagonistic activities of glucocorticoid and mineralocorticoid receptors. Then, we found that when HepG2 cells were exposed to TMPP, TPHP and TDBPP, the main metabolic sub-network disturbances focused on metabolism linked with oxidative stress, osmotic pressure equilibrium, and glucocorticoid and mineralocorticoid receptor antagonist activities; this was also true for TNBP and TDCIPP. Meanwhile, the other OPFRs mainly affected oxidative stress and amino acid metabolism. With multivariate statistical analysis, we found many differential metabolites in each group. Notably, Trimethylamine‑N‑oxide (TMAO) was the differential metabolite in six of the tested OPFRs, excluding TMPP, TPHP and TDBPP, and was one of the potential cardiovascular biomarkers. The data provided here could be helpful in gaining a more in-depth understanding of the metabolic disturbances of these nine OPFRs and may offer a new perspective for understanding potential pollutants with endocrine-disrupting effects on host metabolism.

Effects of the Chiral Fungicides Metalaxyl and Metalaxyl-M on the Earthworm Eisenia fetida as Determined by ¹H-NMR-Based Untargeted Metabolomics

Although metalaxyl and metalaxyl-M are widely used fungicides, very little is known about their subacute and enantiospecific effects on the earthworm metabolome. In this study, Eisenia fetida were exposed to metalaxyl and metalaxyl-M at three concentrations (0.5, 5 and 50 mg/kg) for seven days. ¹H nuclear magnetic resonance (¹H-NMR)-based untargeted metabolomics showed that metalaxyl and metalaxyl-M exposure disturbed earthworms’ metabolism at all three concentrations. Endogenous metabolites, such as succinate, arginine, aspartate, urea, asparagine, alanine, trimethylamine, taurine, cysteine, serine, threonine, histidine, lysine, glucose, choline, carnitine, citric acid, alpha-ketoisovaleric acid, fumaric acid and so on, were significantly changed. These results indicate that metalaxyl and metalaxyl-M produce different, enantiospecific disturbances in the earthworm metabolism, particularly in the tricarboxylic acid (TCA) and urea cycles. The application of untargeted metabolomics thus provides more information for evaluating the toxic risks of metalaxyl and metalaxyl-M.

1H NMR-based serum metabolomics analysis of the age-related metabolic effects of perinatal exposure to BPA, BPS, BPF, and BPAF in female mice offspring

The widespread application of bisphenols (BPs) in the industry has made them ubiquitous in the environment, causing potential environmental risks. Its unknown impacts on human being have received more and more attention. In this study, we have assessed the metabolic effects of perinatal exposure to bisphenol A (BPA) and its substitutes (bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF)) in female mice adolescent offspring and female mice adulthood offspring. ¹H NMR-based serum metabolomics showed that metabolic profiles were disturbed with BPA and its three substitutes exposure in female mice adolescent offspring and female mice adulthood offspring. In addition, age-related metabolic effects were found based on changes in serum endogenous metabolites and metabolic pathways. Specifically, metabolic pathway analysis showed that major disturbed metabolic pathways in female mice adulthood offspring compare with female mice adolescent offspring also changed significantly. With the increase of age of the female mice offspring, changes in the metabolic pathways became more obvious in the BPA treatment group. Conversely, partially disturbed metabolic pathways were restored in the BPS, BPF, and BPAF treatment groups. In conclusion, perinatal exposure to BPA and its three substitutes significantly interferes with metabolic profiles and metabolic pathways, and this metabolic effects were age-related. These results offer more detailed information about the age-related metabolic effects of perinatal exposure to BPA, BPS, BPF, and BPAF in female mice offspring and provide data for systematic evaluation of the health risk assessment of BPA and its substitutes.

The chirality of imazethapyr herbicide selectively affects the bacterial community in soybean field soil

The chiral herbicide imazethapyr (IM) is frequently used to control weeds in soybean fields in northeast China. However, the impact of IM enantiomers on microbial communities in soil is still unknown. Genetic markers (16S rRNA V3-V4 regions) were used to characterize and evaluate the variation of the bacterial communities potentially effected by IM enantiomers. Globally, the bacterial community structure based on the OTU profiles in (-)-R-IM-treated soils was significantly different from those in (+)-S-IM-treated soils, and the differences were enlarged with the treatment dose increasing. Interestingly, the Rhizobiaceae family and several other beneficial bacteria, including Bradyrhizobium, Methylobacterium, and Paenibacillus, were strongly enriched in (-)-R-IM treatment compared to (+)-S-IM treatment. In contrast, the pathogenic bacteria, including Erwinia, Pseudomonas, Burkholderia, Streptomyces, and Agrobacterium, were suppressed in the presence of (-)-R-IM compared to (+)-S-IM. Furthermore, we also observed that the bacterial community structure in (-)-R-IM-treated soils was more quickly restored to its original state compared with those in (+)-S-IM-treated soils. These findings unveil a new role of chiral herbicide in the development of soil microbial ecology and provide theoretical support for the application of low-persistence, high-efficiency, and eco-friendly optical rotatory (-)-R-IM.

3,2-Hydroxypyridinone-Grafted Chitosan Oligosaccharide Nanoparticles as Efficient Decorporation Agents for Simultaneous Removal of Uranium and Radiation-Induced Reactive Oxygen Species in Vivo

Most of the key radionuclides in the nuclear fuel cycle, such as actinides, possess a combination of heavy metal chemotoxicity and radiotoxicity and therefore represent a severe threat to the ecological environment and public safety. The radiotoxicity originates from direct radiation-induced organ damage and indirect damage, mostly through radiation-induced reactive oxygen species (ROS). Although effective chelating agents that can accelerate the excretion of actinides, such as uranium, have been developed in the past several decades, very few of them can reduce radiation-induced damage from internal contamination. In fact, the strategy of simultaneous removal of actinides and their induced-ROS in vivo has scarcely been considered. Here, we report a 3,2-hydroxypyridinone-grafted chitosan oligosaccharide nanoparticle (COS-HOPO) as a new type of decorporation agent that is effective for the removal of both uranium and ROS in vivo. The cytotoxicity and decorporation assays indicate that the marriage of chitosan oligosaccharide (COS) and hydroxypyridinone (HOPO) gives rise to a remarkable decrease in toxicity and promotion of the uranium removal capability from both kidneys and femurs. The decorporation efficacy can reach up to 43% in rat proximal tubular epithelial cells (NRK-52E), 44% in kidneys, and 32% in femurs. Moreover, the ROS levels of the cells treated with COS-HOPO are significantly lower than those of the control group, implying a promising radiation protection effect. The detoxification mechanism of COS-HOPO is closely related to both chelating U(VI)- and scavenging U(VI)-induced intracellular ROS.