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Jiang X, Xiao L, Chen Y, Huang C, Wang J, Tang X, Wan K, Xu H. Degradation of the Novel Heterocyclic Insecticide Pyraquinil in Water: Kinetics, Degradation Pathways, Transformation Products Identification, and Toxicity Assessment. J Agric Food Chem 2023. [PMID: 37378629 DOI: 10.1021/acs.jafc.3c01971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
As new pesticides are continuously introduced into agricultural systems, it is essential to investigate their environmental behavior and toxicity effects to better evaluate their potential risks. In this study, the degradation kinetics, pathways, and aquatic toxicity of the new fused heterocyclic insecticide pyraquinil in water under different conditions were investigated for the first time. Pyraquinil was classified as an easily degradable pesticide in natural water, and hydrolyzes faster in alkaline conditions and at higher temperatures. The formation trends of the main transformation products (TPs) of pyraquinil were also quantified. Fifteen TPs were identified in water using ultrahigh-performance liquid chromatography coupled to quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Orbitrap-HRMS) and Compound Discoverer software, which adopted suspect and nontarget screening strategies. Among them, twelve TPs were reported for the first time and 11 TPs were confirmed by synthesis of their standards. The proposed degradation pathways have demonstrated that the 4,5-dihydropyrazolo[1,5-a]quinazoline skeleton of pyraquinil is stable enough to retain in its TPs. ECOSAR prediction and laboratory tests showed that pyraquinil was "very toxic" or "toxic" to aquatic organisms, while the toxicities of all of the TPs are substantially lower than that of pyraquinil except for TP484, which was predicted to pose a higher toxicity. The results are important for elucidating the fate and assessing the environmental risks of pyraquinil, and provide guidance for scientific and reasonable use.
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Affiliation(s)
- Xunyuan Jiang
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Lu Xiao
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Yan Chen
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Congling Huang
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Jiale Wang
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Xuemei Tang
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Kai Wan
- Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, and Key Laboratory of Testing and Evaluation for Agro-product Safety and Quality (Guangzhou), Ministry of Agriculture and Rural Affairs, Guangzhou 510640, China
| | - Hanhong Xu
- National Key Laboratory of Green Pesticide and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510640, China
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Zhang X, Li Z. Generalizing routes of plant exposure to pesticides by plant uptake models to assess pesticide application efficiency. Ecotoxicol Environ Saf 2023; 262:115145. [PMID: 37327522 DOI: 10.1016/j.ecoenv.2023.115145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/31/2023] [Accepted: 06/12/2023] [Indexed: 06/18/2023]
Abstract
Pesticide application techniques are critical not only for integrated pest management (IPM) but also for food and environmental safety. Assessing pesticide application efficiency on plants can help optimize IPM and reduce pesticide environmental impacts. With hundreds of pesticides registered for use in agriculture, this study proposed a modeling approach based on plant uptake models for generalizing routes of plant chemical exposures that can correspond to different types of pesticide application methods and evaluating their respective efficiency on plants. Three representative pesticide application methods (i.e., drip irrigation, foliar spray, and broadcast application) were selected for modeling simulations. The simulation results for three representative pesticides (i.e., halofenozide, pymetrozine, and paraquat) revealed that the soil-based transpiration exposure route facilitated the bioaccumulation of moderately lipophilic compounds in leaves and fruits. While the plant surface-based exposure route (i.e., leaf cuticle penetration) made it easier for highly lipophilic compounds to enter plants, moderately lipophilic pesticides (i.e., log KOW ∼ 2) were more soluble in phloem sap, which enhanced their subsequent transport within plant tissues. In general, moderately lipophilic pesticides had the highest simulated residue concentrations in plant tissues for the three specific application methods, indicating they had the highest application efficiency due to their enhanced uptake routes (via transpiration and surface penetration) and increased solubility in xylem and phloem saps. Compared to foliar spray and broadcast application, drip irrigation produced higher residue concentrations for a wide variety of pesticides, exhibiting the highest application efficiency for many pesticides, especially for moderately lipophilic compounds. Future research should incorporate plant growth stages, crop safety, pesticide formulations, and multiple application events into the modeling approach for understanding pesticide application efficiency evaluation.
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Affiliation(s)
- Xiaoyu Zhang
- School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong 518107, China
| | - Zijian Li
- School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong 518107, China.
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Altare N, Vione D. Photochemical Implications of Changes in the Spectral Properties of Chromophoric Dissolved Organic Matter: A Model Assessment for Surface Waters. Molecules 2023; 28:2664. [PMID: 36985638 PMCID: PMC10055727 DOI: 10.3390/molecules28062664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 03/18/2023] Open
Abstract
Chromophoric dissolved organic matter (CDOM) is the main sunlight absorber in surface waters and a very important photosensitiser towards the generation of photochemically produced reactive intermediates (PPRIs), which take part in pollutant degradation. The absorption spectrum of CDOM (ACDOM(λ), unitless) can be described by an exponential function that decays with increasing wavelength: ACDOM(λ) = 100 d DOC Ao e− Sλ, where d [m] is water depth, DOC [mgC L−1] is dissolved organic carbon, Ao [L mgC−1 cm−1] is a pre-exponential factor, and S [nm−1] is the spectral slope. Sunlight absorption by CDOM is higher when Ao and DOC are higher and S is lower, and vice versa. By the use of models, here we investigate the impact of changes in CDOM spectral parameters (Ao and S) on the steady-state concentrations of three PPRIs: the hydroxyl radical (•OH), the carbonate radical (CO3•−), and CDOM excited triplet states (3CDOM*). A first finding is that variations in both Ao and S have impacts comparable to DOC variations on the photochemistry of CDOM, when reasonable parameter values are considered. Therefore, natural variability of the spectral parameters or their modifications cannot be neglected. In the natural environment, spectral parameters could, for instance, change because of photobleaching (prolonged exposure of CDOM to sunlight, which decreases Ao and increases S) or of the complex and still poorly predictable effects of climate change. A second finding is that, while the steady-state [3CDOM*] would increase with increasing ACDOM (increasing Ao, decreasing S), the effect of spectral parameters on [•OH] and [CO3•−] depends on the relative roles of CDOM vs. NO3− and NO2− as photochemical •OH sources.
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Cho Y, Jeon HJ, Kim K, Kim C, Lee SE. Developmental toxicity of a pymetrozine photo-metabolite, 3-pyridinecarboxaldehyde, in zebrafish (Danio rerio) embryos: Abnormal cardiac development and occurrence of heart dysfunction via differential expression of heart formation-related genes. Ecotoxicol Environ Saf 2023; 253:114654. [PMID: 36801540 DOI: 10.1016/j.ecoenv.2023.114654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/05/2023] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
Pymetrozine (PYM) is worldwide used to control sucking insect pests in rice-cultivated fields and it is degraded into various metabolites including 3-pyridinecarboxaldehyde (3-PCA). These two pyridine compounds were used to determine their impacts on aquatic environments, particularly on the aquatic animal model zebrafish (Danio rerio). PYM did not show acute toxicities in terms of lethality, hatching rate, and phenotypic changes in zebrafish embryos in the tested ranges up to a concentration of 20 mg/L. 3-PCA exhibited acute toxicity with LC50 and EC50 values of 10.7 and 2.07 mg/L, respectively. 3-PCA treatment caused phenotypic changes including pericardial edema, yolk sac edema, hyperemia, and curved spine, at a concentration of 10 mg/L after 48 h of exposure. Abnormal cardiac development was observed in 3-PCA-treated zebrafish embryos at a concentration of 5 mg/L with reduced heart function. In a molecular analysis, cacna1c, encoding a voltage-dependent calcium channel, was significantly down-regulated in the 3-PCA-treated embryos, indicating synaptic and behavioral defects. Hyperemia and incomplete intersegmental vessels were observed in 3-PCA-treated embryos. Based on these results, it is necessary to generate scientific information on the acute and chronic toxicity of PYM and its metabolites with regular monitoring of their residues in aquatic environments.
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Affiliation(s)
- Yerin Cho
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Hwang-Ju Jeon
- Red River Research Station, Louisiana State University Agricultural Center, Bossier City, LA, USA
| | - Kyeongnam Kim
- Institute of Quality and Safety Evaluation of Agricultural Products, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Chaeeun Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Sung-Eun Lee
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea; Institute of Quality and Safety Evaluation of Agricultural Products, Kyungpook National University, Daegu 41566, Republic of Korea; Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea.
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Ouyang Q, Pang Y, Yuan C, Tan H, Li X, Chen G. Theoretical investigation on the reaction mechanism of UTP cyclohydrolase. Phys Chem Chem Phys 2022; 24:17641-17653. [PMID: 35833743 DOI: 10.1039/d2cp01740g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nucleoside triphosphate cyclohydrolase (UrcA) is a critical enzyme of the uracil catabolism pathway that catalyses the two-step hydrolysis of uridine triphosphate (UTP). Although the recently resolved X-ray structure of UrcA in complex with substrate analogue dUTP provided insights into the structural characteristics of the enzyme, the detailed catalytic mechanism, including how the reaction intermediate accomplishes conformational conversion in the active centre, remains unclear. In this study, extensive DFT calculations and MD simulations were performed to investigate the catalytic reaction process of UrcA. This study shows that the first hydrolytic reactions in UrcA follow a three-step mechanism, while the second hydrolytic reaction follows a two-step mechanism. Glu392 plays a critical role in deprotonating the lytic water in both hydrolytic reactions. The rate-limiting step of the first hydrolytic reaction lies in the cleavage of the uracil ring, in which an extraneous water molecule bridges the proton transfer from C6-OH to N1 to enable the reaction to go through a six-membered transition state with relatively low steric tension. In the second hydrolytic reaction, Glu392 abstracts protons from the lytic water and directly transfers them to the nitrogen atom of the cleaved C4-N3 bond so that the hydrolytic reaction is no longer rate-limited by the C-N bond cleavage step. MD simulations show that the reaction intermediate experiences spontaneous conformation overturn in the active site of UrcA under the assistance of the hydrogen bond interaction from Tyr307 to place its C4-N3 bond alongside the Zn2+ centre of the enzyme to trigger the second hydrolytic reaction.
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Affiliation(s)
- Qingwen Ouyang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
| | - Yunjie Pang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
| | - Chang Yuan
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
| | - Hongwei Tan
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
| | - Xichen Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
| | - Guangju Chen
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
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