title: The identification of the metabolites of chlorothalonil in zebrafish (Danio rerio) and their embryo toxicity and endocrine effects at environmentally relevant levels.
abstract: Chlorothalonil is a broad spectrum fungicide with high annual production and environmental contamination. Despite its high consumption, studies regarding the potential ecological risks of chlorothalonil, especially its metabolites, to aquatic organisms are still limited. In this study, we selected the zebrafish (Danio rerio) as the in vivo model and first identified the metabolite (4-hydroxychlorothalonil) of chlorothalonil in zebrafish by tandem quadrupole/orthogonal-acceleration time-of-flight (Q-TOF). Then, the in vivo and in vitro models were applied to comprehensively estimate the embryo toxicity and potential endocrine effect of chlorothalonil and 4-hydroxychlorothalonil. The data from zebrafish embryo toxicity showed that the lowest observed effect concentrations of both chlorothalonil and 4-hydroxychlorothalonil were 50 μg/L after 96 h of exposure. The mortality rate of the 4-hydroxychlorothalonil was 2.6-fold higher than that of the parent compound at the concentration of 50 μg/L. Dual-luciferase reporter gene assays indicated that both chlorothalonil and 4-hydroxychlorothalonil exerted estrogen receptor α (ERα) agonist activity with REC20values of 2.4 × 10-8M and 3.6 × 10-8M, respectively. However, only 4-hydroxychlorothalonil exhibited both thyroid receptor β (TRβ) agonistic and antagonistic activities. Lastly, we employed molecular docking to predict the binding affinity of chlorothalonil and 4-hydroxychlorothalonil with ERα or TRβ. The results revealed that the potential endocrine effect of chlorothalonil and 4-hydroxychlorothaloni might be attributed to the different binding affinities with the receptors. In conclusion, our studies revealed that 4-hydroxychlorothalonil exhibited potent endocrine-disrupting effects compared to its parent compound, chlorothalonil. The results provided here remind us that the assessment of the potential ecological and health risks of the metabolites of fungicides in addition to their parent compounds should arouse great concerns.
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Chenyang
authors.initials: C
authors.lastname: Ji
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Yan
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Meiya
authors.initials: M
authors.lastname: Lu
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China; Department of Environmental Health, Harvard T.H. Chan School of Public Health 665 Huntington Avenue, Building 1, Room G3, Boston, MA 02115, USA.
authors.forename: Chensheng
authors.initials: C
authors.lastname: Lu
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China. Electronic address: zhaomr@zjut.edu.cn.
authors.forename: Meirong
authors.initials: M
authors.lastname: Zhao
mesh_terms: D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D004625:Embryo, Nonmammalian / Q000187:drug effects* / Q000378:metabolism; D052244:Endocrine Disruptors / Q000378:metabolism / Q000633:toxicity*; D047628:Estrogen Receptor alpha / Q000819:agonists; D005659:Fungicides, Industrial / Q000378:metabolism / Q000633:toxicity*; D062105:Molecular Docking Simulation; D009570:Nitriles / Q000378:metabolism / Q000633:toxicity*; D037042:Thyroid Hormone Receptors beta / Q000819:agonists / Q000037:antagonists & inhibitors; D015027:Zebrafish / Q000196:embryology / Q000378:metabolism*
chemical_list: D052244:Endocrine Disruptors; D047628:Estrogen Receptor alpha; D005659:Fungicides, Industrial; D009570:Nitriles; D037042:Thyroid Hormone Receptors beta; C005806:tetrachloroisophthalonitrile
keywords: 4-hydroxychlorothalonil; Chlorothalonil; Developmental toxicity; Endocrine disrupting effects