Enantioselective bioaccumulation, oxidative stress, and thyroid disruption assessment of cis-metconazole enantiomers in zebrafish (Danio rerio)
Graphical abstract
Introduction
Due to expanding need of food and economic development, the global consumption of pesticides has been sharply increasing in agricultural fields in recent years. However, excessive use of pesticides has raised serious environmental contamination and risks to non-target organisms and human health (Singh et al., 2018). For example, reactive oxygen species (ROS) and protein peroxidation in medaka fish reduced after exposure to propiconazole, and gene expression of the cytochrome P450 CYP1A in medaka fish was upregulated (Tu et al., 2016). The level of triiodothyronine in zebrafish larvae exposed to hexaconazole and tebuconazole rose sharply, while the concentration of thyroxine significantly decreased, indicating that thyroid endocrine disruption occurred in zebrafish larvae (Yu et al., 2013). Thus, reducing of agrochemicals in ecosystems can greatly minimize their potential risks to human beings and non-target organisms.
Triazole pesticides are a kind of the most popular fungicides in crop protection and they possess broad-spectrum antifungal activities against pathogenic fungi. Most of them have good chemical stability in the environment and cause potential adverse effects to non-target organisms, including cytotoxicity, reproductive toxicity, and endocrine disruption, etc. For instance, hatching rate and heart rate of zebrafish embryos remarkably reduced after exposure to difenoconazole, further leading to cardiovascular deformities (Zhu et al., 2021). After treating with tebuconazole, ROS in HCT116 cells significantly increased, thereby resulting in lipid peroxidation and DNA fragmentation (Othmène et al., 2021). More importantly, approximately 84% of triazole fungicides are chiral (Zhang et al., 2019b). As well-known, enantiomers have identical chemical and physical properties, while most of them show enantioselective toxicity, absorption, distribution, and degradation behaviors in living bodies (Gao et al., 2019; Xu et al., 2018; Pan et al., 2020). In the study of Nie group, (R)-etoxazole was preferentially accumulated in zebrafish as compared to (S)-enantiomer, and the antioxidant enzymes in zebrafish remarkably changed, indicating that oxidative stress effects occurred in zebrafish when exposed to etoxazole (Chang et al., 2020). In addition, movement behavior of zebrafish embryos exposed to (+)-penconazole dramatically reduced as compared to (-)-penconazole, and the expression of acetylcholinesterase genes induced by (+)-penconazole was down-regulated, which indicated that (+)-penconazole possessed much stronger developmental toxicity and neurotoxicity in comparison with (-)-penconazole (Xiang et al., 2019). Moreover, triazole fungicides have been identified as a type of endocrine disrupting chemicals toward both wildlife and human beings (Zhang et al., 2019a; Li et al., 2020). Thus, systematic investigation of chiral triazole pesticides at enantiomeric level will give us useful information for their risk assessments.
Metconazole (abbreviated as MEZ) has been widely used in the control of Fusarium head blight (Tateishi et al., 2014). MEZ has two chiral carbon atoms and occurs in two pairs of diastereoisomers and two enantiomeric pairs. MEZ exhibits stereoselective toxicity to M. flos-aquae and Chlorella pyrenoidosa (Deng et al., 2019; Li et al., 2021). For that MEZ is stable in the aquatic environment, the half-life of MEZ in water and sediments ranged from 1∼15 days and 116∼814 days, respectively (USEPA 2007). MEZ residues in environmental matrices will recirculate among soil, water and sediment, and slowly bioaccumulate in aquatic organisms and human beings through food chain, finally resulting in serious damages of biological functions in non-target organisms (Martinez and Al-Ahmad, 2019). However, there is still little information regarding the enantioselective bioaccumulation and endocrine disruption of cis-MEZ (Fig. S1) in non-target organisms, since cis-MEZ accounts for 90% in the commercial MEZ products.
Herein, bioaccumulation of cis-MEZ enantiomers in zebrafish has been explored using chiral liquid chromatography-tandem spectrometry. Uptake rate constant (k1), depuration rate constant (k2), the bioconcentration factor (BCFk), and the half-life of cis-MEZ enantiomers were obtained to illustrate their enantioselective behaviors. Then, the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione-S transferase (GST), as well as the content of malondialdehyde (MDA) in zebrafish were determined to reveal the oxidative stress effects of zebrafish caused by MEZ. Moreover, the levels of triiodothyronine (T3) and thyroxine (T4) in zebrafish were assessed in order to elaborate enantioselective endocrine disruption induced by cis-MEZ.
Section snippets
Chemicals and materials
MEZ racemate (purity > 98%) was provided from Yingde Greatchem Chemicals Co. Ltd. (Yingde, China). (1S, 5R)-MEZ and (1R, 5S)-MEZ (enantiomeric excess > 98%) were obtained through chiral separating MEZ racemate according to our reported method (He et al., 2018). The standard solutions of (1S, 5R)-MEZ and (1R, 5S)-MEZ (50 mg⋅mL−1) were obtained through dissolving corresponding amount in dimethylsulfoxide (DMSO), respectively. In addition, the standard solution of MEZ mixture (50 mg×mL−1) was
Method validation
Typical chromatograms of MEZ on an OD chiral column through using the acetonitrile-water mixture (60: 40, v/v) are shown in Supporting Information Fig. S3, in which (1R, 5S)-MEZ was firstly eluted from the chiral column, and the latter-eluted fraction was (1S, 5R)-MEZ. No other substances interfered with the detection of MEZ enantiomers. In addition, the calibration curves, LODs, and LOQs results of cis-MEZ enantiomers in acetonitrile and zebrafish were summarized in Table S1. Good linear
Conclusions
In summary, stereoselective acute toxicity, bioaccumulation, oxidative stress, and thyroid disruption of cis-MEZ enantiomers have been assessed through using zebrafish as an aquatic organism model in this work. The order of the acute toxicity of MEZ against zebrafish was found to be (1R, 5S)-MEZ > the mixture > (1S, 5R)-MEZ. Then, the bioaccumulation results indicated that (1R, 5S)-MEZ was preferentially bioaccumulated in zebrafish than (1S, 5R)-MEZ. Moreover, (1R, 5S)-MEZ showed much stronger
CRediT authorship contribution statement
Rujian He: Methodology, Data curation, Writing – original draft. Dong Guo: Methodology, Investigation, Validation. Chun Lin: Formal analysis, Writing – review & editing. Wei-guang Zhang: Supervision, Funding acquisition. Jun Fan: Supervision, Conceptualization, Writing – review & editing.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
We gratefully acknowledged financial support from National Natural Science Foundation of China (No. 92056113), Natural Science Foundation of Guangdong Province (No. 2018A030313193) and Foundation of Young Talents in Higher Education of Guangdong, China (No. 2017KQNCX239).
References (40)
- et al.
Etoxazole stereoselective determination, bioaccumulation, and resulting oxidative stress in Danio rerio (zebrafish)
Ecotox. Environ. Safe.
(2020) - et al.
Enantioselective bioaccumulation and toxicity of rac-sulfoxaflor in zebrafish (Danio rerio)
Sci. Total Environ.
(2022) - et al.
Stereoselective toxicity of metconazole to the antioxidant defenses and the photosynthesis system of Chlorella pyrenoidosa
Aquat. Toxicol.
(2019) - et al.
A potential biomarker of isofenphos-methyl in humans: a chiral view
Environ. Int.
(2019) - et al.
Enantioselective determination of metconazole in multi matrices by high-performance liquid chromatography
Talanta
(2018) - et al.
Systematic investigation of stereochemistry, stereoselective bioactivity, and antifungal mechanism of chiral triazole fungicide metconazole
Sci. Total Environ.
(2021) - et al.
Stereoselective environmental behavior and biological effects of the chiral bitertanol
Sci. Total Environ.
(2020) - et al.
Enantioselective effects of the fungicide metconazole on photosynthetic activity in Microcystis flos-aquae
Ecotox. Environ. Safe.
(2021) - et al.
Chiral bioaccumulation behavior of tebuconazole in thez ebrafish (Danio rerio)
Ecotox. Environ. Safe.
(2016) - et al.
Effects of glyphosate and aminomethylphosphonic acid on an isogeneic model of the human blood-brain barrier
Toxicol. Lett.
(2019)
The enantioselective toxicity and oxidative stress of betacypermethrin on zebrafish
Environ. Pollut.
Tebuconazole induced cytotoxic and genotoxic effects in HCT116 cells through ROS generation
Pest. Biochem. Phys.
Bioaccumulation, metabolism and endocrine-reproductive effects of metolachlor and its S-enantiomer in adult zebrafish (Danio rerio)
Sci.Total Environ
A systematic evaluation of zoxamide at enantiomeric level
Sci. Total. Environ.
ROS signaling, oxidative stress and Nrf2 in pancreatic beta-cell function
Toxicol. App. Pharm.
Thyroid hormones in growth and development of fish
Comp. Biochemi. Physiol. C Toxicol. Pharmacol.
Embryonic exposure to prothioconazole induces oxidative stress and apoptosis in zebrafish (Danio rerio) early life stage
Sci. Total. Environ.
Early life exposure to a rodent carcinogen propiconazole fungicide induces oxidative stress and hepatocarcinogenesis in medaka fish
Aquat. Toxicol.
Free radicals and antioxidants in normal physiological functions and human disease
Int. J. Biochem. Cell Biol.
Enantioselectivity of toxicological responses induced by maternal exposure of cis-bifenthrin enantiomers in zebrafish (Danio rerio) larvae
J. Hazard. Mater.
Cited by (8)
Stereoselective cardiotoxic effects of metconazole on zebrafish (Danio rerio) based on AGE-RAGE signalling pathway
2024, Science of the Total EnvironmentIn vitro exposure to triazoles used as fungicides impairs human granulosa cells steroidogenesis
2023, Environmental Toxicology and PharmacologyStereoselective, Diastereoselective Dissipation and Risk Assessment of Chiral Metconazole in Soybean, Peanut, Cabbage, Celery, Tomato, and Soil
2023, Journal of Agricultural and Food Chemistry