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Zhu L, Xu G, Zhang Q, Wang G, Wang W, Wang Q. Semirational Design Strategy To Enhance the Thermostability and Catalytic Activity of Cytochrome P450 105D7 for the Degradation of the Pharmaceutically Active Compounds: Diclofenac. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:15681-15690. [PMID: 38668375 DOI: 10.1021/acs.est.3c10482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Pharmaceutically active compounds are an important category of emerging pollutants, and their biological transformation processes in the environment are crucial for understanding and evaluating the migration, transformation, and environmental fate of emerging pollutants. The cytochrome P450 105 enzyme family has been proven to play an important role in the degradation of exogenous environmental pollutants. However, its thermostability and catalytic activity still need to be improved to better adapt to complex environmental conditions. This work elucidates the key mechanisms and important residues of the degradation reaction through multiple computational strategies, establishes a mutation library, and obtains 21 single-point mutation designs. Experimental verification showed that 16 single mutants had enhanced thermostability, with the R89F and L197Y mutants showing the highest increases in thermostability at 135 and 119% relative to the wild-type enzyme, respectively. Additionally, as a result of the higher specific activity of D390Q, it was selected for combination mutagenesis, ultimately resulting in three combination mutants (R89F/L197Y, R89F/D390Q, and R89F/L197Y/D390Q) with enhanced thermostability and catalytic activity. This study provides a modification approach for constructing efficient enzyme variants through semirational design and can contribute to the development of control technologies for emerging pollutants.
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Affiliation(s)
- Ledong Zhu
- Environment Research Institute, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Guochao Xu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Guoqiang Wang
- Environment Research Institute, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao, Shandong 266237, People's Republic of China
| | - Qiao Wang
- Environment Research Institute, Shandong University, Qingdao, Shandong 266237, People's Republic of China
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Song Z, Yu X, Zhu M, Wu Z, Fu Z, Chen J. Distinct Species-Specific and Toxigenic Metabolic Profiles for 6PPD and 6PPD Quinone by P450 Enzymes: Insights from In Vitro and In Silico Studies. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 39120070 DOI: 10.1021/acs.est.4c03361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
The tire rubber antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and its quinone product (6PPDQ) are prevalent emerging contaminants, yet their biotransformation profiles remain poorly understood, hampering the assessment of environmental and health risks. This study investigated the phase-I metabolism of 6PPD and 6PPDQ across aquatic and mammalian species through in vitro liver microsome (LM) incubations and in silico simulations. A total of 40 metabolites from seven pathways were identified using the highly sensitive nano-electrospray ionization mass spectrometry. Notably, 6PPDQ was consistently detected as a 6PPD metabolite with an approximate 2% yield, highlighting biotransformation as a neglected indirect exposure pathway for 6PPDQ in organisms. 6PPDQ was calculated to form through a facile two-step phenyl hydroxylation of 6PPD, catalyzed by cytochrome P450 enzymes. Distinct species-specific metabolic kinetics were observed, with fish LM demonstrating retarded biotransformation rates for 6PPD and 6PPDQ compared to mammalian LM, suggesting the vulnerability of aquatic vertebrates to these contaminants. Intriguingly, two novel coupled metabolites were identified for 6PPD, which were predicted to exhibit elevated toxicity compared to 6PPDQ and result from C-N oxidative coupling by P450s. These unveiled metabolic profiles offer valuable insights for the risk assessment of 6PPD and 6PPDQ, which may inform future studies and regulatory actions.
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Affiliation(s)
- Zehua Song
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention Technology, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Xiaomei Yu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention Technology, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Minghua Zhu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention Technology, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Zimeng Wu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention Technology, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Zhiqiang Fu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention Technology, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention Technology, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
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Li Q, Cui Y, Wang Z, Li Y, Yang H. Toxicity assessment of dioxins and their transformation by-products from inferred degradation pathways. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 937:173416. [PMID: 38795989 DOI: 10.1016/j.scitotenv.2024.173416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/17/2024] [Accepted: 05/19/2024] [Indexed: 05/28/2024]
Abstract
Due to the significant POPs characteristics, dioxins caused concern in public health and environmental protection. Evaluating the toxicity risk of dioxin degradation pathways is critical. OCDD, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF, which are highly abundant in the environment and have strong biodegradation capabilities, were selected as precursor molecules in this study. Firstly, their transformation pathways were deduced during the metabolism of biometabolism, microbial aerobic, microbial anaerobic, and photodegradation pathways, and density function theory (DFT) was used to calculate the Gibbs free energy to infer the possibility of the occurrence of the transformation pathway. Secondly, the carcinogenic potential of the precursors and their degradation products was evaluated using the TOPKAT modeling method. With the help of the positive indicator (0-1) normalization method and heat map analysis, a significant increase in the toxic effect of some of the transformation products was found, and it was inferred that it was related to the structure of the transformation products. Meanwhile, the strength of the endocrine disrupting effect of dioxin transformation products was quantitatively assessed using molecular docking and subjective assignment methods, and it was found that dioxin transformation products with a higher content of chlorine atoms and molecules similar to those of thyroid hormones exhibited a higher risk of endocrine disruption. Finally, the environmental health risks caused by each degradation pathway were comprehensively assessed with the help of the negative indicator (1-2) standardization method, which provides a theoretical basis for avoiding the toxicity risks caused by dioxin degradation transformation. In addition, the 3D-QSAR model was used to verify the necessity and rationality of this study. This paper provides theoretical support and reference significance for the toxicity assessment of dioxin degradation by-products from inferred degradation pathways.
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Affiliation(s)
- Qing Li
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China.
| | - Yuhan Cui
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China.
| | - Zhonghe Wang
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Yu Li
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Hao Yang
- College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China.
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Ma G, Ma K, Zhang J, Zhao X, Wang Q, Chen Y, Lu J, Wei X, Wang X, Yu H. Mechanistic insight into biotransformation of novel triazine-based flame retardant 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazinane-2,4,6-trione by human cytochrome P450s. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 348:123883. [PMID: 38548154 DOI: 10.1016/j.envpol.2024.123883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/21/2024]
Abstract
The escalating focus on the environmental occurrence and toxicology of emerging pollutants underscores the imperative need for a profound exploration of their metabolic transformations mediated by human CYP450 enzymes. Such investigations have the potential to unravel the intricate metabolite profiles, substantially altering the toxicological outcomes. In this study, we integrated the computational simulations with in vitro metabolism experiments to investigate the metabolic activity and mechanism of an emerging pollutant, 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazinane-2,4,6-trione (TDBP-TAZTO), catalyzed by human CYP450s. The results highlight the important contributions of CYP2E1, 3A4 and 2C9 to the biotransformation of TDBP-TAZTO, leading to the identification of four distinct metabolites. The effective binding conformations governing biotransformation reactions of TDBP-TAZTO within active CYP450s are unveiled. Structural instability of primary hydroxyTDBP-TAZTO products suggests three potential outcomes: (1) generation of an alcohol metabolite through successive debromination and reduction reactions, (2) formation of a dihydroxylated metabolite through secondary hydroxylation by CYP450, and (3) production of an N-dealkylated metabolite via decomposition and isomerization reactions in the aqueous environment. The formation of a desaturated debrominated metabolite may arise from H-abstraction and barrier-free Br release during the primary oxidation, potentially competing with the generation of hydroxyTDBP-TAZTO. These findings provide detailed mechanistic insight into TDBP-TAZTO biotransformation by CYP450s, which can enrich our understanding of the metabolic fate and associated health risk of this chemical.
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Affiliation(s)
- Guangcai Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Kan Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Jing Zhang
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Xianglong Zhao
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Qiuyi Wang
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Yewen Chen
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Jiayu Lu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Xueyu Wang
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China; Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Shuren Street 8, 310015, Hangzhou, China.
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Zhang X, Liu Y. Computational Insights into the Catalysis of the pH Dependence of Bromite Decomposition Catalyzed by Chlorite Dismutase from Dechloromonas aromatica ( DaCld). Inorg Chem 2024; 63:6776-6786. [PMID: 38572830 DOI: 10.1021/acs.inorgchem.4c00126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
The heme-containing chlorite dismutases catalyze the rapid and efficient decomposition of chlorite (ClO2-) to yield Cl- and O2, and the catalytic efficiency of chlorite dismutase from Dechloromonas aromatica (DaCld) in catalyzing the decomposition of bromite (BrO2-) was dependent on pH, which was supposed to be caused by the conversion of active Cpd I to the inactive Cpd II by proton-coupled electron transfer (PCET) from the pocket Tyr118 to the propionate side chain of heme at high pH. However, the direct evidence of PCET and how the pH affects the efficiency of DaCld, as well as whether Cpd II is really inactive, are still poorly understood. Here, on the basis of the high-resolution crystal structures, the computational models in both acidic (pH 5.0) and alkaline (pH 9.0) environments were constructed, and a series of quantum mechanical/molecular mechanical calculations were performed. On the basis of our calculation results, the O-Br bond cleavage of BrO2- always follows the homolytic mode to generate Cpd II rather than Cpd I. It is different from the O-O cleavage of O2/H2O2 or peracetic acid catalyzed by the other heme-containing enzymes. Thus, in the subsequent O-O rebound reaction, it is the Fe(IV)═O in Cpd II that combines with the O-Br radical. Because the porphyrin ring in Cpd II does not bear an unpaired electron, the previously suggested PCET from Tyr118 to the propionate side chain of heme was not theoretically recognized in an alkaline environment. In addition, the O-O rebound step in an alkaline solution corresponds to an energy barrier that is larger than that in an acidic environment, which can well explain the pH dependence of the activity of DaCld. In addition, the protonation state of the propionic acid side chains of heme and the surrounding hydrogen bond networks were calculated to have a significant impact on the barriers of the O-O rebound step, which is mainly achieved by affecting the reactivity of the Fe(IV)═O group in Cpd II. In an acidic environment, the relatively weaker coordination of the O2 atom to Fe leads to its higher reactivity toward the O-O rebound reaction. These observations may provide useful information for understanding the catalysis of chlorite dismutases.
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Affiliation(s)
- Xianghui Zhang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
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Meng M, Zhai Z, Zhang Z, Kim J, Zhu Y. Metabolism of an insecticide fipronil by soil fungus Cunninghamella elegans ATCC36112. Arch Microbiol 2023; 205:264. [PMID: 37316622 DOI: 10.1007/s00203-023-03594-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/25/2023] [Accepted: 05/21/2023] [Indexed: 06/16/2023]
Abstract
In this study, the metabolic pathway of the phenylpyrazole insecticide fipronil in Cunninghamella elegans (C. elegans) was investigated. Approximately 92% of fipronil was removed within 5 days, and seven metabolites were accumulated simultaneously. The structures of the metabolites were completely or tentatively identified by GC-MS and 1H, 13C NMR. To determine the oxidative enzymes involved in metabolism, piperonyl butoxide (PB) and methimazole (MZ) were used, and the kinetic responses of fipronil and its metabolites were determined. PB strongly inhibited fipronil metabolism, while MZ weakly inhibited its metabolism. The results suggest that cytochrome P450 (CYP) and flavin-dependent monooxygenase (FMO) may participate in fipronil metabolism. Integrated metabolic pathways can be inferred from the control and inhibitor experiments. Several novel products from the fungal transformation of fipronil were identified, and similarities between C. elegans transformation and mammalian metabolism of fipronil were compared. Therefore, these results will help to gain insight into the fungal degradation of fipronil and potential applications in fipronil bioremediation. At present, microbial degradation of fipronil is the most promising approach and maintains environmental sustainability. In addition, the ability of C. elegans to mimic mammalian metabolism will assist in illustrating the metabolic fate of fipronil in mammalian hepatocytes and assess its toxicity and potential adverse effects.
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Affiliation(s)
- Min Meng
- College of Plant Health and Medicine, Qingdao Agricultural University, Changcheng Rd, Chengyang, Qingdao City, 266-109, Shandong Province, China
| | - Zhaochi Zhai
- College of Plant Health and Medicine, Qingdao Agricultural University, Changcheng Rd, Chengyang, Qingdao City, 266-109, Shandong Province, China
| | - Zhenxing Zhang
- College of Plant Health and Medicine, Qingdao Agricultural University, Changcheng Rd, Chengyang, Qingdao City, 266-109, Shandong Province, China
| | - Jeonghan Kim
- Department of Agricultural Biotechnology, Seoul National University, 599 Gwanak-ro, Silim-dong, Gwanak-Gu, Seoul, 151-742, Republic of Korea
| | - Yongzhe Zhu
- College of Chemistry and Pharmacy, Qingdao Agricultural University, Changcheng Rd, Chengyang, Qingdao City, 266-109, Shandong Province, China.
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Guo F, Tian Y, Ji S, Min H, Ding W, Yu H, Li Y, Ji L. Environmental biotransformation mechanisms by flavin-dependent monooxygenase: A computational study. CHEMOSPHERE 2023; 325:138403. [PMID: 36921778 DOI: 10.1016/j.chemosphere.2023.138403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 03/01/2023] [Accepted: 03/12/2023] [Indexed: 06/18/2023]
Abstract
The enzyme-catalyzed metabolic biotransformation of xenobiotics plays a significant role in toxicology evolution and subsequently environmental health risk assessment. Recent studies noted that the phase I human flavin-dependent monooxygenase (e.g., FMO3) can catalyze xenobiotics into more toxic metabolites. However, details of the metabolic mechanisms are insufficient. To fill the mechanism in the gaps, the systemic density functional theory calculations were performed to elucidate diverse FMO-catalyzed oxidation reactions toward environmental pollutants, including denitrification (e.g., nitrophenol), N-oxidation (e.g., nicotine), desulfurization (e.g., fonofos), and dehalogenation (e.g., pentachlorophenol). Similar to the active center compound 0 of cytochrome P450, FMO mainly catalyzed reactions with the structure of the tricyclic isoalloxazine C-4a-hydroperoxide (FADHOOH). As will be shown, FMO-catalyzed pathways are more favorable with a concerted than stepwise mechanism; Deprotonation is necessary to initiate the oxidation reactions for phenolic substrates; The regioselectivity of nicotine by FMO prefers the N-oxidation other than N-demethylation pathway; Formation of the P-S-O triangle ring is the key step for desulfurization of fonofos by FMO. We envision that these fundamental mechanisms catalyzed by FMO with a computational method can be extended to other xenobiotics of similar structures, which may aid the high-throughput screening and provide theoretical predictions in the future.
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Affiliation(s)
- Fangjie Guo
- Quality and Safety Engineering Institute of Food and Drug, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Yilin Tian
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Shujing Ji
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Hao Min
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Wen Ding
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Yingqi Li
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, 718 East Haizhou Road, Haining 314400, China
| | - Li Ji
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China; School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China.
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Gao Y, Hu X, Deng C, Wang M, Niu X, Luo N, Ji Y, Li G, An T. New insight into molecular mechanism of P450-Catalyzed metabolism of emerging contaminants and its consequence for human health: A case study of preservative methylparaben. ENVIRONMENT INTERNATIONAL 2023; 174:107890. [PMID: 37001212 DOI: 10.1016/j.envint.2023.107890] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Hydroxylated metabolites in the living body are considered as a potential biomarker of exposure to emerging contaminations (ECs) and breast cancer, but their formation mechanism has not received enough attention. Besides, the adverse impacts of metabolites during the metabolic transformation of ECs largely remain unknown. In this study, we employed a density functional calculation combing with in-vitro incubation of human liver microsomes to explore the bio-transformation of preservative methylparaben (MPB) in human bodies. Our results showed that hydroxylated metabolites of MPB (OH-MPB) were observed experimentally, while a formation mechanism was revealed at the molecular level. That is, hydroxylated metabolite was exclusively formed via the hydrogen abstraction from the phenolic hydroxyl group of MPB followed by the OH-rebound pathway, rather than the direct hydroxylation on the benzene ring. The increasing of hydroxyl groups on ECs could improve the metabolisms. This was confirmed in the metabolism of ECs without hydroxyl group and with multiple-hydroxyl groups, respectively. Furthermore, toxicity assessments show that compared to parent MPB, the hydroxylated metabolites have increased negative impacts on the gastrointestinal system and liver. A semiquinone product exhibits potential damage in the cardiovascular system and epoxides are toxic to the blood and gastrointestinal system. The findings deepen our insight into the biotransformation of parabens in human health, especially by providing health warnings about the potential impacts caused by semiquinone and epoxides.
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Affiliation(s)
- Yanpeng Gao
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Xinyi Hu
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Chuyue Deng
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Mei Wang
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Xiaolin Niu
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Na Luo
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Yuemeng Ji
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
| | - Guiying Li
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Taicheng An
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
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9
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Khan AUH, Naidu R, Dharmarajan R, Fang C, Shon H, Dong Z, Liu Y. The interaction mechanisms of co-existing polybrominated diphenyl ethers and engineered nanoparticles in environmental waters: A critical review. J Environ Sci (China) 2023; 124:227-252. [PMID: 36182134 DOI: 10.1016/j.jes.2021.10.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 06/16/2023]
Abstract
This review focuses on the occurrence and interactions of engineered nanoparticles (ENPs) and brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) in water systems and the generation of highly complex compounds in the environment. The release of ENPs and BFRs (e.g. PBDEs) to aquatic environments during their usage and disposal are summarised together with their key interaction mechanisms. The major interaction mechanisms including electrostatic, van der Waals, hydrophobic, molecular bridging and steric, hydrogen and π-bonding, cation bridging and ligand exchange were identified. The presence of ENPs could influence the fate and behaviour of PBDEs through the interactions as well as induced reactions under certain conditions which increases the formation of complex compounds. The interaction leads to alteration of behaviour for PBDEs and their toxic effects to ecological receptors. The intermingled compound (ENPs-BFRs) would show different behaviour from the parental ENPs or BFRs, which are currently lack of investigation. This review provided insights on the interactions of ENPs and BFRs in artificial, environmental water systems and wastewater treatment plants (WWTPs), which are important for a comprehensive risk assessment.
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Affiliation(s)
- Anwar Ul Haq Khan
- Global Centre for Environmental Remediation (GCER), College of Engineering Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), ATC Building, The University of Newcastle, Callaghan, NSW 2308, Australia.
| | - Ravi Naidu
- Global Centre for Environmental Remediation (GCER), College of Engineering Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), ATC Building, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Raja Dharmarajan
- Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), ATC Building, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Cheng Fang
- Global Centre for Environmental Remediation (GCER), College of Engineering Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), ATC Building, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Hokyong Shon
- School of Civil and Environmental Engineering, University of Technology Sydney (UTS), City Campus, Broadway, NSW 2007, Australia
| | - Zhaomin Dong
- School of Space and Environment, Beihang University, Beijging 100191, China
| | - Yanju Liu
- Global Centre for Environmental Remediation (GCER), College of Engineering Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), ATC Building, The University of Newcastle, Callaghan, NSW 2308, Australia.
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10
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Yang R, Ye Y, Chen Y, Yang Y, Yang L, Yao Y, Zhong W, Zhu L. First Insight into the Formation of In Vivo Transformation Products of 2-Ethylhexyl diphenyl phosphate in Zebrafish and Prediction of Their Potential Toxicities. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:451-462. [PMID: 36515636 DOI: 10.1021/acs.est.2c05506] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
As a frequently detected organophosphorus flame retardant in the environment, 2-ethylhexyl diphenyl phosphate (EHDPHP) is vulnerable to biotransformation, while the transformation mechanisms and potential toxicities of its transformation products remain unclear. In the present study, in vivo transformation products of EHDPHP in exposed zebrafish for 21d were analyzed by suspect screening and identified by mass spectrometry. Fifteen metabolites were identified, including 10 phase I and 5 phase II products with monohydroxylated products being primary, among which 5-OH-EHDPHP was the most predominant. Two sulfation products and one terminal desaturation metabolite of EHDPHP were reported for the first time. A density functional calculation coupled with molecular docking disclosed that the specific conformation of EHDPHP docked in the protein pockets favored the primary formation of 5-OH-EHDPHP, which was fortified to be a more suitable biomarker of EHDPHP exposure. The in vitro tests suggested that EHDPHP transformation took place not only in liver but also in intestine, where gut microbes played an important role. Due to lack of standards, in silico toxicity prediction combined with molecular docking indicated that several metabolites potentially cause higher toxicities than EHDPHP. The results provide deep insight into the potential health risks due to specific in vivo transformation of EHDPHP.
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Affiliation(s)
- Rongyan Yang
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Yongxiu Ye
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Ying Chen
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Yi Yang
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Liping Yang
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Yiming Yao
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Wenjue Zhong
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
| | - Lingyan Zhu
- Key Laboratory of Pollution Processes and Environmental Criteria of Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering of Nankai University, Tianjin 300350, China
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11
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Xu Q, Li J, Cao S, Ma G, Zhao X, Wang Q, Wei X, Yu H, Wang Z. Thyroid hormone activities of neutral and anionic hydroxylated polybrominated diphenyl ethers to thyroid receptor β: A molecular dynamics study. CHEMOSPHERE 2023; 311:136920. [PMID: 36273606 DOI: 10.1016/j.chemosphere.2022.136920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 10/09/2022] [Accepted: 10/16/2022] [Indexed: 06/16/2023]
Abstract
Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been identified as the strong endocrine disrupting chemicals to humans, which show structural similarity with endogenous thyroid hormones (THs) and thus disrupt the functioning of THs through competitive binding with TH receptors (TRs). Although previous studies have reported the hormone activities of some OH-PBDEs on TH receptor β (TRβ), the interaction mechanism remains unclear. Furthermore, hydroxyl dissociation of OH-PBDEs may alter their TR disrupting activities, which has not yet been investigated in depth. In this work, we selected 18 OH-PBDEs with neutral and anionic forms and performed molecular dynamics (MD) simulations to estimate their binding interactions with the ligand binding domain (LBD) of TRβ. The results demonstrate that most of OH-PBDEs have stronger binding affinities to TRβ-LBD than their anionic counterparts, and the hydroxyl dissociation of ligands differentiate the major driving force for their binding. More Br atoms in OH-PBDEs can result in stronger binding potential with TRβ-LBD. Moreover, 5 hydrophobic residues, including Met313, Leu330, Ile276, Leu346, and Phe272, are identified to have important contributions to bind OH-PBDEs. These results clarify the binding mechanism of OH(O-)-PBDEs to TRβ-LBD at the molecular level, which can provide a solid theoretical basis for accurate assessment of TH disrupting effects of these chemicals.
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Affiliation(s)
- Qi Xu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Jian Li
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China; Institute of Physical Oceanography and Remote Sensing, Ocean College, Zhejiang University, Zheda Road 1, 316021, Zhoushan, China
| | - Shang Cao
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Guangcai Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China.
| | - Xianglong Zhao
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Qiuyi Wang
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China.
| | - Zhiguo Wang
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou, 311121, China
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12
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Liu Z, Fei Y, Xia Z, Zhang R, Chang X, Ji Y, Kong D, Lu J, Chen J. Insights into the oxidation of bisphenol A by peracetic acid enhanced with bromide: The role of free bromine. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Zhang T, Cheng F, Yang H, Zhu B, Li C, Zhang YN, Qu J, Peijnenburg WJGM. Photochemical degradation pathways of cell-free antibiotic resistance genes in water under simulated sunlight irradiation: Experimental and quantum chemical studies. CHEMOSPHERE 2022; 302:134879. [PMID: 35551936 DOI: 10.1016/j.chemosphere.2022.134879] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
The presence of antibiotic resistance genes (ARGs) in the environment poses a threat to human health and therefore their environmental behavior needs to be studied urgently. A systematic study was conducted on the photodegradation pathways of the cell-free tetracycline resistance gene (Tc-ARG) under simulated sunlight irradiation. The results showed that Tc-ARG can undergo direct photodegradation, which significantly reduces its horizontal transfer efficiency. Suwannee River fulvic acid (SRFA) promoted the photodegradation of Tc-ARG and further inhibited its horizontal transfer by generating reactive intermediates. The photodegradation of Tc-ARG was attributed to degradation of the four bases (G, C, A, T) and the deoxyribose group. Quantum chemical calculations showed that the four bases could be oxidized by the hydroxyl radical (HO) through addition and H-abstraction reactions. The main oxidative product 8-oxo-dG was detected. This product was generated through the addition reaction of G-C with HO, subsequent to dissolved oxygen initiated H-abstraction and H2O catalyzed H-transfer reactions. The predicted maximum photodegradation rates of Tc-ARG in the Yellow River estuary were 0.524, 0.937, and 0.336 h-1 in fresh water, estuary water, and seawater, respectively. This study furthermore revealed the microscopic photodegradation pathways and obtained essential degradation parameters of Tc-ARG in sunlit surface water.
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Affiliation(s)
- Tingting Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Fangyuan Cheng
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Hao Yang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Boyi Zhu
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Chao Li
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Ya-Nan Zhang
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China.
| | - Jiao Qu
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, 130117, China.
| | - Willie J G M Peijnenburg
- Institute of Environmental Sciences, Leiden University, Leiden, the Netherlands; National Institute of Public Health and the Environment (RIVM), Center for Safety of Substances and Products, Bilthoven, the Netherlands
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14
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Feng S, Li Y, Zhang R, Zhang Q, Wang W. Origin of metabolites diversity and selectivity of P450 catalyzed benzo[a]pyrene metabolic activation. JOURNAL OF HAZARDOUS MATERIALS 2022; 435:129008. [PMID: 35490637 DOI: 10.1016/j.jhazmat.2022.129008] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
Polycyclic Aromatic Hydrocarbon (PAHs) presents one of the most abundant class of environmental pollutants. Recent study shows a lab-synthesized PAHs derivative, helicenium, can selectively kill cancer cells rather than normal cells, calling for the in-depth understanding of the metabolic process. However, the origin of metabolites diversity and selectivity of P450 catalyzed PAHs metabolic activation is still unclear to a great extent. Here we systematically investigated P450 enzymes catalyzed activation mechanism of a representative PAHs, benzo[a]pyrene (BaP), and found the corresponding activation process mainly involves two elementary steps: electrophilic addition and epoxidation. Electrophilic addition step is evidenced to be rate determining step. Two representative binding modes of BaP with P450 were found, which enables the electrophilic addition of Heme (FeO) to almost all the carbons of BaP. This electrophilic addition was proposed to be accelerated by the P450 enzyme environment when compared with the gas phase and water solvent. To dig deeper on the origin of metabolites diversity, we built several linear regression models to explore the structural-energy relationships. The selectivity was eventually attributed to the integrated effects of structural (e.g. O-C distance and O-C-Fe angle) and electrostatic parameters (e.g. charge of C and O) from both BaP and P450.
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Affiliation(s)
- Shanshan Feng
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Yanwei Li
- Environment Research Institute, Shandong University, Qingdao 266237, PR China.
| | - Ruiming Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
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15
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Hu X, Wu JL, Miao W, Long F, Pan H, Peng T, Yao X, Li N. Covalent Protein Modification: An Unignorable Factor for Bisphenol A-Induced Hepatotoxicity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:9536-9545. [PMID: 35593067 DOI: 10.1021/acs.est.2c01307] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Covalent modification of proteins by reactive pollutants/metabolites might trigger various toxicities resulting from the disruption of protein structures and/or functions, which is critical for understanding the mechanism of pollutants-induced toxicity. However, this mechanism has rarely been touched on due to the lack of a methodology. In this research, the protein modification of bisphenol A (BPA) in rats was characterized using a series of liquid chromatography-tandem mass spectrometry (LC-MS) approaches. BPA-modified cysteine (Cys1) was first released from proteins via enzymatic hydrolysis and identified using LC-MS. Moreover, the positive correlation between Cys1 and hepatotoxicity indicated the involvement of protein modification in BPA toxicity. Then, in vitro incubation of BPA with amino acids and protein confirmed that BPA could specifically modify cysteine residues of proteins after bioactivation and provided four additional modification patterns. Finally, 24 BPA-modified proteins were identified from the liver of BPA-exposed rats using proteomic analysis, and they were mainly enriched in oxidative stress-related pathways. The modification on superoxide dismutases, catalase, and glutathione S-transferases disrupted their enzymatic functions, leading to oxidative damage. These results revealed that the covalent protein modification is an unignorable factor for BPA hepatotoxicity. Moreover, the workflow can be applied to identify protein adducts of other emerging contaminants and possible risk.
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Affiliation(s)
- Xiaolan Hu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa 999078, Macau SAR, China
| | - Jian-Lin Wu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa 999078, Macau SAR, China
| | - Wen Miao
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa 999078, Macau SAR, China
| | - Fei Long
- Sino-French Hoffmann Institute, School of Basic Medical Science, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, Guangzhou 510180, China
| | - Hudan Pan
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa 999078, Macau SAR, China
| | - Tao Peng
- Sino-French Hoffmann Institute, School of Basic Medical Science, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, Guangzhou 510180, China
| | - Xiaojun Yao
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa 999078, Macau SAR, China
| | - Na Li
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa 999078, Macau SAR, China
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16
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Yadav R, Awasthi N, Kumar D. Biotransformation of BPA via epoxidation catalyzed by Cytochrome P450. INORG CHEM COMMUN 2022. [DOI: 10.1016/j.inoche.2022.109321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Computational Insight into Biotransformation Profiles of Organophosphorus Flame Retardants to Their Diester Metabolites by Cytochrome P450. Molecules 2022; 27:molecules27092799. [PMID: 35566150 PMCID: PMC9102461 DOI: 10.3390/molecules27092799] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 04/24/2022] [Accepted: 04/26/2022] [Indexed: 02/05/2023] Open
Abstract
Biotransformation of organophosphorus flame retardants (OPFRs) mediated by cytochrome P450 enzymes (CYPs) has a potential correlation with their toxicological effects on humans. In this work, we employed five typical OPFRs including tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tris(1-chloro-2-propyl) phosphate (TCIPP), tri(2-chloroethyl) phosphate (TCEP), triethyl phosphate (TEP), and 2-ethylhexyl diphenyl phosphate (EHDPHP), and performed density functional theory (DFT) calculations to clarify the CYP-catalyzed biotransformation of five OPFRs to their diester metabolites. The DFT results show that the reaction mechanism consists of Cα-hydroxylation and O-dealkylation steps, and the biotransformation activities of five OPFRs may follow the order of TCEP ≈ TEP ≈ EHDPHP > TCIPP > TDCIPP. We further performed molecular dynamics (MD) simulations to unravel the binding interactions of five OPFRs in the CYP3A4 isoform. Binding mode analyses demonstrate that CYP3A4-mediated metabolism of TDCIPP, TCIPP, TCEP, and TEP can produce the diester metabolites, while EHDPHP metabolism may generate para-hydroxyEHDPHP as the primary metabolite. Moreover, the EHDPHP and TDCIPP have higher binding potential to CYP3A4 than TCIPP, TCEP, and TEP. This work reports the biotransformation profiles and binding features of five OPFRs in CYP, which can provide meaningful clues for the further studies of the metabolic fates of OPFRs and toxicological effects associated with the relevant metabolites.
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18
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Zhang S, Li X, Wang Y, Wei J, Zhang X, Liu Y. Computational Study of the Peroxygenase Mechanism Catalyzed by Hemoglobin Dehaloperoxidase Involved in the Degradation of Chlorophenols. Inorg Chem 2022; 61:2628-2639. [PMID: 35080380 DOI: 10.1021/acs.inorgchem.1c03721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biochemical evidence showed that hemoglobin dehaloperoxidase (DHP B) from Amphitrite Ornata is a multifunctional hemoprotein that catalyzes both dehalogenation and hydroxylation of halophenols via the peroxidase and peroxygenase mechanism, respectively, which sets the basis for the degradation of halophenols. In the peroxygenase mechanism, the reaction was previously suggested to be triggered either by the hydrogen atom abstraction by the Fe═O center or by the proton abstraction by His55. To illuminate the peroxygenase mechanism of DHP B at the atomistic level, on the basis of the high-resolution crystal structure, computational models were constructed, and a series of quantum mechanical/molecular mechanical calculations have been performed. According to the calculation results, the pathway (Path a) initiated by the H-abstraction by the Fe═O center is feasible. In another pathway (Path b), His55 can abstract the proton from the hydroxyl group of the substrate (4-Cl-o-cresol) to initiate the reaction; however, its feasibility depends on the prior electron transfer from the substrate to the porphyrin group. The rate-limiting step of Path a is the OH-rebound, which corresponds to an energy barrier of 14.7 kcal/mol at the quartet state. His55 acts as an acid-base catalyst and directly involves in the catalysis. Our mutant study indicates that His55 can be replaced by other titratable residues. These findings may provide useful information for further understanding of the catalytic reaction of DHP B and for the design of enzymes in the degradation of pollutants, in particular, halophenols.
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Affiliation(s)
- Shiqing Zhang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Xinyi Li
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yijing Wang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Jingjing Wei
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Xue Zhang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
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19
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Han C, Zhu W, Ma G, Chen Y, Li X, Wei X, Yu H. Computational insight into biotransformation of halophenols by cytochrome P450: Mechanism and reactivity for epoxidation. CHEMOSPHERE 2022; 286:131708. [PMID: 34352543 DOI: 10.1016/j.chemosphere.2021.131708] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/11/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
Halophenols (XPs) have aroused great interests due to their high toxicity and low biodegradability. Previous experimental studies have shown that XPs can be catalytically transformed into epoxides and haloquinones by cytochrome P450 enzymes (CYPs). However, these metabolites have never been detected directly. Moreover, the effects of the reaction site and the type and number of halogen substituents on the biotransformation reactivity of halophenols still remain unknown. In this work, we performed density functional theory (DFT) calculations to simulate the CYP-mediated biotransformation of 36 XPs with mono-, di-, and tri-halogen (F, Cl, and Br) substitutions to unravel the mechanism and relevant kinetics of XPs epoxidation. The whole epoxidation process consists of initial rate-determining O-addition and subsequent ring-closure steps. The simulation results show that the epoxidation in low-spin (LS) state is kinetically preferred over that in high-spin (HS) state, and the formation of epoxide metabolite is strongly exothermic. For all XPs, the epoxidation reactivity follows the order of ortho/para O-addition > meta O-addition. Moreover, the O-addition with higher energy barriers roughly corresponds to chlorophenols and fluorophenols with more halogen atoms. Compared with dichlorophenols, the additional ortho-Cl substitution on trichlorophenols can slightly increase the energy barriers of meta O-addition. By contrast, the additional inclusion of an ortho-Cl to monochlorophenols enhances the meta O-addition reactivity of dichlorophenols. Overall, the present work clarifies the biotransformation routes of XPs to produce epoxides, and identifies the key factors affecting the epoxidation reactivity, which are beneficial in understanding comprehensively the metabolic fate and toxicity of XPs.
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Affiliation(s)
- Cenyang Han
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Wenyou Zhu
- School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
| | - Guangcai Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China.
| | - Yewen Chen
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Xinqi Li
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, 321004, Jinhua, China.
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20
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Zhang Y, Liu J, Ghoshal S, Moores A. Density Functional Theory Calculations Decipher Complex Reaction Pathways of 6:2 Fluorotelomer Sulfonate to Perfluoroalkyl Carboxylates Initiated by Hydroxyl Radical. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16655-16664. [PMID: 34882405 DOI: 10.1021/acs.est.1c05549] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
6:2 Fluorotelomer sulfonate (6:2 FTSA) is a ubiquitous environmental contaminant belonging to the family of per- and polyfluoroalkyl substances. Previous studies showed that hydroxyl radical (•OH) efficiently transforms 6:2 FTSA into perfluoroalkyl carboxylates (PFCAs) of different chain lengths (C2-C7), yet the reaction mechanisms were not elucidated. This study used density functional theory (DFT) calculations to map the entire reaction path of 6:2 FTSA initiated by •OH and experimentally verified the theoretical results. Optimal reaction pathways were obtained by comparing the rate constants calculated from the transition-state theory. We found that 6:2 FTSA was first transformed to C7 PFCA and C6F13•; C6F13• was then further reacted to C2-C6 PFCAs. The parallel addition of •OH and O2 to CnF2n+1• was essential to producing C2-C6 PFCAs. The critical step is the generation of alkoxyl radicals, which withdraw electrons from the adjacent C-C groups to result in chain cleavage. The validity of the calculated optimal reaction pathways was further confirmed by the consistency with our experimental data in the aspects of O2 involvement, identified intermediates, and the final PFCA profile. This study provides valuable insight into the transformation of polyfluoroalkyl substances containing aliphatic carbons in •OH-based oxidation processes.
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Affiliation(s)
- Yanyan Zhang
- Department of Civil Engineering, McGill University, Montreal, Quebec H3A 0C3, Canada
- Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou 310024, Zhejiang Province, China
| | - Jinxia Liu
- Department of Civil Engineering, McGill University, Montreal, Quebec H3A 0C3, Canada
| | - Subhasis Ghoshal
- Department of Civil Engineering, McGill University, Montreal, Quebec H3A 0C3, Canada
| | - Audrey Moores
- Center for Green Chemistry and Catalysis, Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
- Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0E9, Canada
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21
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Gu C, Fan X, Ti Q, Yang X, Bian Y, Sun C, Jiang X. Mechanistic insight into hydroxylation of 2,2',4,4'-tetrabromodiphenyl ether during biodegradation by typical aerobic bacteria: Experimental and computational studies. JOURNAL OF HAZARDOUS MATERIALS 2021; 416:126132. [PMID: 34492924 DOI: 10.1016/j.jhazmat.2021.126132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/29/2021] [Accepted: 05/12/2021] [Indexed: 06/13/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are a group of persistent pollutants in the environment. Though aerobic biodegradation of PBDEs have been extensively studied, the involved hydroxylation mechanism decisive for whole biotransformation is not clear yet. During the effective biodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by B. xenovorans LB400, the depletion of endogenous ∙OH by scavenger could bring about the significant decrease of biodegradation efficiency whereas ·O2- was nearly not influential. Given the importance of ∙OH in hydroxylation, the reaction mechanisms along major pathways of electrophilic addition and hydrogen abstraction were theoretically examined by density functional theory (DFT). For the less demand of activation energy, the relative preference of electrophilic addition was shown at aromatic C3-site. When the secondary reaction was considered after addition at C4-site, the barrierless association of ∙OH at C3-site and deprotonation by H2O was validated as the energetically-favorable pathway that may cause dihydroxylation of BDE-47 into 3,4-dihydroxyl-BDE-17. The electrophilic addition followed by seconary barrierless trans-association of ∙OH and then dehydration seemed favorable for monohydroxylation as regards energetic barrier merely up to 194.01 kJ mol-1, while the hydrogen abstraction by ∙OH from C5-site was more privileged actually. The theoretical insights would help well understand the hydroxylation mechanism of PBDEs by aerobes.
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Affiliation(s)
- Chenggang Gu
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China.
| | - Xiuli Fan
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China
| | - Qingqing Ti
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China
| | - Xinglun Yang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China
| | - Yongrong Bian
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China
| | - Cheng Sun
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, PR China
| | - Xin Jiang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China
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22
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Rautela R, Arya S, Vishwakarma S, Lee J, Kim KH, Kumar S. E-waste management and its effects on the environment and human health. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 773:145623. [PMID: 33592459 DOI: 10.1016/j.scitotenv.2021.145623] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/13/2021] [Accepted: 01/30/2021] [Indexed: 05/23/2023]
Abstract
Challenges in managing electronic waste (E-waste) arise from a lack of technical skills, poor infrastructure, inadequate financial support, and inactive community engagement. This study provides a systematic review of efforts to overcome these challenges in the context of inappropriate recycling protocols of E-waste and their toxic effects on human health and the environment. An inventory of end-of-life electronic products, which can be established through the creation of an environment friendly regulatory regime for recycling, is essential for the proper control of E-waste. An approach has been articulated to help implement effective management of E-waste in both developed and developing countries. Enforcement of systematic management measures for E-waste in developing countries coupled with best practices is expected to minimize adverse impacts while helping maintain a sustainable and resilient environment.
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Affiliation(s)
- Rahul Rautela
- CSIR- National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur 440 020, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Shashi Arya
- CSIR- National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur 440 020, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Shilpa Vishwakarma
- CSIR- National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur 440 020, India
| | - Jechan Lee
- Department of Environmental and Safety Engineering, Ajou University, Suwon 16499, Republic of Korea; Department of Energy Systems Research, Ajou University, Suwon 16499, Republic of Korea
| | - Ki-Hyun Kim
- Department of Civil and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea.
| | - Sunil Kumar
- CSIR- National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur 440 020, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201 002, India.
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23
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Zhang H, Sanidad KZ, Zhu L, Parsonnet J, Haggerty TD, Zhang G, Cai Z. Frequent occurrence of triclosan hydroxylation in mammals: A combined theoretical and experimental investigation. JOURNAL OF HAZARDOUS MATERIALS 2021; 407:124803. [PMID: 33338815 DOI: 10.1016/j.jhazmat.2020.124803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/07/2020] [Accepted: 12/06/2020] [Indexed: 06/12/2023]
Abstract
Triclosan (TCS) is a widespread antimicrobial agent with many adverse health risks. Its hepatoxicity invariably points to the activation of constitutive androstane receptor (CAR), which regulates cytochrome P450 (CYP) genes that are critical for oxidative metabolism. Here, we provide the theoretical and experimental evidences showing that metabolic activation of TCS frequently occurs through aromatic hydroxylation in mammals. CYP-mediated oxidation was predicted to take place at each aromatic C‒H bond. Molecular docking and in vitro approaches reveal oxidative reaction could be efficiently catalyzed by CAR-regulated CYP2B6 enzyme. Parallel reaction monitoring (PRM) high-resolution mass spectrometry was utilized to identify and profile TCS oxidative metabolites in paired mouse liver, bile, feces, plasma and urine. We found multiple hydroxylated isomers including the products generated via the NIH shift of chlorine, as well as their subsequent conjugates. These metabolites showed isomer-specific retention in mice. Glucuronide conjugates are more readily excreted than the sulfates. Moreover, for the first time, isomeric hydroxylated metabolites were detected in the urine and stool of human subjects used TCS-contained household and personal care products. Collectively, these findings suggest that hydroxylation is an important, yet often underestimated element that worth considering to fully evaluate the biological fates and health risks of TCS.
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Affiliation(s)
- Hongna Zhang
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, 999077 Hong Kong, China
| | - Katherine Z Sanidad
- Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Lin Zhu
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, 999077 Hong Kong, China
| | - Julie Parsonnet
- Department of Medicine and Department of Health Research and Policy, Stanford University, Stanford, CA 94305, USA
| | - Thomas D Haggerty
- Department of Medicine and Department of Health Research and Policy, Stanford University, Stanford, CA 94305, USA
| | - Guodong Zhang
- Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA.
| | - Zongwei Cai
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, 999077 Hong Kong, China.
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24
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Wang M, Gao Y, Li G, An T. Increased adverse effects during metabolic transformation of short-chain chlorinated paraffins by cytochrome P450: A theoretical insight into 1-chlorodecane. JOURNAL OF HAZARDOUS MATERIALS 2021; 407:124391. [PMID: 33160786 DOI: 10.1016/j.jhazmat.2020.124391] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 10/14/2020] [Accepted: 10/25/2020] [Indexed: 05/22/2023]
Abstract
Short-chain chlorinated paraffins (SCCPs), frequently detected in human tissues or organs, can result in threat to human health by disturbing normal metabolism. However, their metabolism mechanisms and fates are largely unclear. Therefore, to better understand the impacts of SCCPs and their metabolites on the human health, the metabolic mechanism and kinetics of SCCPs by cytochrome P450 enzymes (CYPs) were explored using density functional theory employed 1-chlorodecane as a model SCCPs. The results show that 1-chlorodecane could be readily metabolized by CYPs, and the rate constant reaches up 42.3 s-1 in human body. Dechlorination of 1-chlorodecane is unlikely to occur and hydroxylation is dominated via H-abstraction pathways, especially from the intermediate C atom of 1-chlorodecane. The toxicity assessments suggest that the two metabolites, 10-chloro-decan-5-ol and 1-chlorodecanol could exhibit higher bioaccumulation, carcinogenicity and more serious damage on cardiovascular system after the metabolism of 1-chlorodecane. To our knowledge, this is the first study from the viewpoint of theoretical analysis to explore the metabolism of typical SCCPs in human body. It may provide deep insight into the metabolic transformation mechanism of SCCPs and cause the concerns about the adverse effects of their metabolites in human body.
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Affiliation(s)
- Mei Wang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China
| | - Yanpeng Gao
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China
| | - Guiying Li
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China
| | - Taicheng An
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China.
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25
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Zhu L, Zhou J, Zhang Q, Li Y, Wang W. Computational study on the metabolic activation mechanism of PeCDD by Cytochrome P450 1A1. JOURNAL OF HAZARDOUS MATERIALS 2021; 405:124276. [PMID: 33158646 DOI: 10.1016/j.jhazmat.2020.124276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/30/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Cytochrome P450 enzymes (CYPs) are crucial for metabolizing dioxin compounds such as 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD). Here we have applied molecular dynamic simulations (MD), quantum mechanics/molecular mechanics methods (QM/MM) and density functional theory (DFT) to investigate the metabolic activation and transformation of PeCDD catalyzed by CYP1A1. Our QM/MM calculations highlight that PeCDD can be activated by P450s through the well-known electrophilic addition mechanism with an average energy barrier of 20.9 kcal/mol. Based on the results of previous experimental studies, further conversions of ketone products and epoxidation products that are mediated by P450 enzymes were investigated through DFT calculations. Analysis of the structures via the noncovalent interactions (NCI) method and the distortion-interaction model suggests that amino acids Ser122, Ala317, Ile386 and Leu496 play important roles in the metabolic process.
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Affiliation(s)
- Ledong Zhu
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Jie Zhou
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China.
| | - Yanwei Li
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
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26
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Ma G, Geng L, Lu Y, Wei X, Yu H. Investigating the molecular mechanism of hydroxylated bromdiphenyl ethers to inhibit the thyroid hormone sulfotransferase SULT1A1. CHEMOSPHERE 2021; 263:128353. [PMID: 33297275 DOI: 10.1016/j.chemosphere.2020.128353] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/07/2020] [Accepted: 09/13/2020] [Indexed: 06/12/2023]
Abstract
Hydroxylated bromodiphenyl ethers (OH-BDEs) have raised great concern due to their potential endocrine disrupting effects on humans. In vitro experiments have indicated OH-BDEs can inhibit the activity of thyroid hormone (TH) sulfotransferases (SULTs); however, the molecular mechanism has not been investigated in depth. In this work, we employed 17 OH-BDEs with five or fewer Br atoms, and performed integrated computational simulations to unravel the possible inhibition mechanism of OH-BDEs on human SULT1A1. The molecular docking results demonstrate that OH-BDEs form hydrogen bonds with residues Lys106 and His108, and the neutral OH-BDEs show comparable binding energies with their anionic counterparts. The further hybrid quantum mechanical/molecular mechanical (QM/MM) calculations unravel a metabolic mechanism of OH-BDEs comprised by proton abstraction and sulfation steps. This mechanism is involved in the SULT1A1 inhibition by some OH-BDEs comprised of three or fewer Br atoms, while other OH-BDEs likely only form ternary complexes to competitively inhibit SULT1A1 activity. Moreover, the effect of the hydroxyl group of OH-BDEs on SULT1A1 inhibition potential follows the order of ortho-OH BDE > meta-OH BDE > para-OH BDE. These results provide an insight into the inhibition mechanism of OH-BDEs to SULT1A1 at the molecular level, which are beneficial in illuminating the molecular initiating events involved in the TH disruption of OH-BDEs.
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Affiliation(s)
- Guangcai Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua, 321004, China
| | - Liming Geng
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua, 321004, China
| | - Yuchen Lu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua, 321004, China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua, 321004, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua, 321004, China.
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27
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Yue Y, Chen J, Bao L, Wang J, Li Y, Zhang Q. Fluoroacetate dehalogenase catalyzed dehalogenation of halogenated carboxylic acids: A QM/MM approach. CHEMOSPHERE 2020; 254:126803. [PMID: 32361540 DOI: 10.1016/j.chemosphere.2020.126803] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 04/11/2020] [Accepted: 04/12/2020] [Indexed: 06/11/2023]
Abstract
Dehalogenation is one of the most important reactions in environmental pollution control, for instance, the degradation of persistent organic pollutants (POPs). Recently, fluoroacetate dehalogenase (FAcD) has been reported to catalyze the dehalogenation reactions, which shows great potential in treating halogenated pollutants. Here the dehalogenation mechanism catalyzed by FAcD was fully deciphered with the aid of quantum mechanics/molecular mechanics method. The results show that FAcD catalyzed dehalogenation efficiency follows the order of defluorination > dechlorination > debromination. The corresponding Boltzmann-weighted average barriers are 10.1, 19.7, and 20.9 kcal mol-1. Positive/negative correlations between activation barriers and structural parameters (e.g. distance and angle) for FAcD catalyzed dechlorination and debromination were established. Based on the structure-energy relationship, we propose that mutation of the binding pocket amino acids (e.g. His155, Trp156, Tyr219) to smaller proton donor amino acids (e.g. Serine, Threonine, Cysteine, Asparagine) may increase the efficiency for dechlorination and debromination. The results may of practical value for the efficient degradation of chlorined and bromined pollutants by harnessing FAcD.
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Affiliation(s)
- Yue Yue
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Jinfeng Chen
- School of Life Sciences, Westlake University, Hangzhou, 310000, PR China
| | - Lei Bao
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Junjie Wang
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Yanwei Li
- Environment Research Institute, Shandong University, Jinan, 250100, PR China.
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
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28
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Song S, Yang C, Shao M, Chao J, Zheng N, Wang W, He Y, Li P. Simultaneous determination of polybrominated diphenyl ethers and hydroxylated analogues in human serum using high-performance liquid chromatography-inductively coupled plasma mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2020; 1147:122130. [DOI: 10.1016/j.jchromb.2020.122130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/14/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022]
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29
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Poston RG, Murphy L, Rejepova A, Ghaninejad-Esfahani M, Segales J, Mulligan K, Saha RN. Certain ortho-hydroxylated brominated ethers are promiscuous kinase inhibitors that impair neuronal signaling and neurodevelopmental processes. J Biol Chem 2020; 295:6120-6137. [PMID: 32229587 PMCID: PMC7196656 DOI: 10.1074/jbc.ra119.011138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 03/23/2020] [Indexed: 12/20/2022] Open
Abstract
The developing nervous system is remarkably sensitive to environmental signals, including disruptive toxins, such as polybrominated diphenyl ethers (PBDEs). PBDEs are an environmentally pervasive class of brominated flame retardants whose neurodevelopmental toxicity mechanisms remain largely unclear. Using dissociated cortical neurons from embryonic Rattus norvegicus, we found here that chronic exposure to 6-OH-BDE-47, one of the most prevalent hydroxylated PBDE metabolites, suppresses both spontaneous and evoked neuronal electrical activity. On the basis of our previous work on mitogen-activated protein kinase (MAPK)/extracellular signal-related kinase (ERK) (MEK) biology and our observation that 6-OH-BDE-47 is structurally similar to kinase inhibitors, we hypothesized that certain hydroxylated PBDEs mediate neurotoxicity, at least in part, by impairing the MEK-ERK axis of MAPK signal transduction. We tested this hypothesis on three experimental platforms: 1) in silico, where modeling ligand-protein docking suggested that 6-OH-BDE-47 is a promiscuous ATP-competitive kinase inhibitor; 2) in vitro in dissociated neurons, where 6-OH-BDE-47 and another specific hydroxylated BDE metabolite similarly impaired phosphorylation of MEK/ERK1/2 and activity-induced transcription of a neuronal immediate early gene; and 3) in vivo in Drosophila melanogaster, where developmental exposures to 6-OH-BDE-47 and a MAPK inhibitor resulted in offspring displaying similarly increased frequency of mushroom-body β-lobe midline crossing, a metric of axonal guidance. Taken together, our results support that certain ortho-hydroxylated PBDE metabolites are promiscuous kinase inhibitors and can cause disruptions of critical neurodevelopmental processes, including neuronal electrical activity, pre-synaptic functions, MEK-ERK signaling, and axonal guidance.
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Affiliation(s)
- Robert G Poston
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, Merced, California 95343
| | - Lillian Murphy
- Department of Biological Sciences, Center for Interdisciplinary Molecular Biology: Education, Research and Advancement (CIMERA), California State University, Sacramento, California 95819
| | - Ayna Rejepova
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, Merced, California 95343
| | - Mina Ghaninejad-Esfahani
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, Merced, California 95343
| | - Joshua Segales
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, Merced, California 95343
| | - Kimberly Mulligan
- Department of Biological Sciences, Center for Interdisciplinary Molecular Biology: Education, Research and Advancement (CIMERA), California State University, Sacramento, California 95819
| | - Ramendra N Saha
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, Merced, California 95343.
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30
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Ma G, Yu H, Han C, Jia Y, Wei X, Wang Z. Binding and Metabolism of Brominated Flame Retardant β-1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane in Human Microsomal P450 Enzymes: Insights from Computational Studies. Chem Res Toxicol 2020; 33:1487-1496. [DOI: 10.1021/acs.chemrestox.0c00076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Guangcai Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Cenyang Han
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Yue Jia
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Zhiguo Wang
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou 311121, China
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31
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Zhou J, Zhu L, Chen J, Wang W, Zhang R, Li Y, Zhang Q, Wang W. Degradation mechanism for Zearalenone ring-cleavage by Zearalenone hydrolase RmZHD: A QM/MM study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 709:135897. [PMID: 31887512 DOI: 10.1016/j.scitotenv.2019.135897] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/01/2019] [Accepted: 12/01/2019] [Indexed: 06/10/2023]
Abstract
The danger of zearalenone (ZEN) as an endocrine disruptor to humans and the environment has aroused increasing attention. In this study, we implemented the quantum mechanics/molecular mechanics (QM/MM) method to investigate the degradation mechanism of ZEN hydrolase (RmZHD) toward ZEN at the atomic level. The degradation process involves two concerted reaction pathways, where the active site contains a Ser-His-Glu triplet as a proton donor. With the Boltzmann-weighted average potential barriers of 18.1 and 21.5 kcal/mol, the process undergoes proton transfer and nucleophilic-substituted ring opening to form a hydroxyl product. Non-covalent interaction analyses elucidated hydrogen bonding between key amino acids with ZEN. The electrostatic influence analysis of 16 amino acids proposes residues Asp34 and His128 as the possible mutation target for future mutation design of enzyme RmZHD. An in-depth investigation of the protein environment of RmZHD can improve the bioremediation efficiency of endocrine disrupting chemicals.
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Affiliation(s)
- Jie Zhou
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Ledong Zhu
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Jinfeng Chen
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Wei Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Ruiming Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Yanwei Li
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China.
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
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32
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Guo F, Chai L, Zhang S, Yu H, Liu W, Kepp KP, Ji L. Computational Biotransformation Profile of Emerging Phenolic Pollutants by Cytochromes P450: Phenol-Coupling Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:2902-2912. [PMID: 31967796 DOI: 10.1021/acs.est.9b06897] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phenols are ubiquitous environmental pollutants, whose biotransformation involving phenol coupling catalyzed by cytochromes P450 may produce more lipophilic and toxic metabolites. Density functional theory (DFT) computations were performed to explore the debated phenol-coupling mechanisms, taking triclosan as a model substrate. We find that a diradical pathway facilitated by compound I and protonated compound II of P450 is favored vs alternative radical addition or electron-transfer mechanisms. The identified diradical coupling resembles a "two-state reactivity" from compound I characterized by significantly high rebound barriers of the phenoxy radicals, which can be formulated into three equations for calculating the ratio [coupling]/[hydroxylation]. A higher barrier for rebound than for H-abstraction in high-spin triclosan can facilitate the phenoxy radical dissociation and thus enable phenol coupling, while H-abstraction/radical rebound causing phenol hydroxylation via minor rebound barriers mostly occurs via the low-spin state. Therefore, oxidation of triclosan by P450 fits the first equation with a ratio [coupling]/[hydroxylation] of 1:4, consistent with experimental data indicating different extents of triclosan coupling (6-40%). The high rebound barrier of phenoxy radicals, as a key for the mechanistic identification of phenol coupling vs hydroxylation, originates from their weak electron donor ability due to spin aromatic delocalization. We envision that the revealed mechanism can be extended to the cross-coupling reactions between different phenolic pollutants, and the coupling reactions of several other aromatic pollutants, to infer unknown metabolites.
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Affiliation(s)
- Fangjie Guo
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Lihong Chai
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Shubin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, P. R. China
| | - Weiping Liu
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Kasper P Kepp
- DTU Chemistry, Technical University of Denmark, Building 206, Kgs. Lyngby DK-2800, Denmark
| | - Li Ji
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
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33
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Liu M, Li N, Zhang Y, Zheng Z, Zhuo Y, Sun B, Bai LP, Zhang M, Guo MQ, Wu JL. Characterization of covalent protein modification by triclosan in vivo and in vitro via three-dimensional liquid chromatography-mass spectrometry: New insight into its adverse effects. ENVIRONMENT INTERNATIONAL 2020; 136:105423. [PMID: 32035293 DOI: 10.1016/j.envint.2019.105423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/26/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Triclosan (TCS), an antimicrobial agent widely used in personal care products and ubiquitously exists in environment, has drawn increasing concern due to its potential to exert multiple adverse effects, ranging from endocrine disruption to carcinogenesis. However, the mechanism of these adverse effects is still not fully elucidated. More and more studies have shown that chemical reactive metabolites (RMs) covalently binding to proteins is a possible reason for these adverse effects, but there is still a lack of appropriate methods to predict or evaluate these adverse effects due to the extremely low abundance of the modified proteins in complex biological samples. In this study, we attempted to address this problem and investigate the possible mechanism of TCS adverse effects by a shotgun proteomics approach based on three-dimensional-liquid chromatography-mass spectrometry (3D-LC-MS). First, the in vitro incubation with model amino acids and protein in microsomes showed that TCS could react with cysteine residue of proteins through 3 types of RMs. Then, a 3D-LC-MS approach was developed to sensitively determine the low abundant modified proteins, which resulted in the identification of 45 TCS-modified proteins, including albumin, haptoglobin and NR1I2, in rats. STRING analysis indicated that these modified proteins mainly were involved in reproductive and development system, endocrine and immune system, and carcinogenesis, which were in accord with the main reported TCS-induced adverse effects and suggested that the covalent modification of TCS RMs for proteins might affect their activities and functions, thus inducing serious adverse effects. This study provided a new insight into the mechanism of TCS adverse effects and may serve as a valuable method to predict or evaluate adverse effects of ubiquitous chemicals.
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Affiliation(s)
- Meixian Liu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau
| | - Na Li
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau.
| | - Yida Zhang
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau
| | - Zhiyuan Zheng
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau
| | - Yue Zhuo
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau
| | - Baoqing Sun
- State Key Laboratory of Respiratory Disease, National Clinical Center for Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, First Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Li-Ping Bai
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau
| | - Mingming Zhang
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Ming-Quan Guo
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China
| | - Jian-Lin Wu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau.
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Chai L, Ji S, Zhang S, Yu H, Zhao M, Ji L. Biotransformation Mechanism of Pesticides by Cytochrome P450: A DFT Study on Dieldrin. Chem Res Toxicol 2020; 33:1442-1448. [DOI: 10.1021/acs.chemrestox.0c00013] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lihong Chai
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Shujing Ji
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Shubin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, China
| | - Meirong Zhao
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
| | - Li Ji
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
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Ma G, Yu H, Xu X, Geng L, Wei X, Wen J, Wang Z. Molecular Basis for Metabolic Regioselectivity and Mechanism of Cytochrome P450s toward Carcinogenic 4-(Methylnitrosamino)-(3-pyridyl)-1-butanone. Chem Res Toxicol 2020; 33:436-447. [PMID: 31889441 DOI: 10.1021/acs.chemrestox.9b00353] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
As an abundantly present tobacco component, carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has also been detected in atmospheric particulate matter, suggesting the ineluctable exposure risk of this contaminant. NNK metabolic activation by cytochrome P450 enzymes (CYPs) is a prerequisite to exerting its genotoxicity, but the metabolic regioselectivity and mechanism are still unknown. Here the binding feature and regioselectivity of CYPs 1A1, 1A2, 2A6, 2A13, 2B6, and 3A4 toward NNK are unraveled through molecular docking and molecular dynamics (MD) simulations. Binding mode analyses reveal that 1A2 and 2B6 have definite preferences for NNK α-methyl hydroxylation, while the other four CYPs preferentially catalyze α-methylene hydroxylation. The binding affinities between NNK and CYPs evaluated by the binding free energies follow the order 2A13 > 2B6 > 1A2 > 2A6 > 1A1 > 3A4. Density functional theory (DFT) calculations are further performed to characterize the mechanism of NNK biotransformation. Results show that the α-hydroxyNNK generated from α-hydroxylation may undergo nonenzymatic decomposition to form genotoxic diazohydroxide and aldehyde, and further oxidation by P450 to yield nitrosamide, which mainly contributes to NNK toxification capacity. Meanwhile the pyridine N-oxidation and denitrosation of Cα-radical intermediate play an important role in detoxifying NNK. Overall, the present study provides the molecular basis for CYP-catalyzed regioselectivity and mechanism of NNK biotransformation, which can enable the identification of metabolites for assessing the health risk of individual NNK exposure.
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Affiliation(s)
- Guangcai Ma
- College of Geography and Environmental Sciences , Zhejiang Normal University , Jinhua 321004 , China
| | - Haiying Yu
- College of Geography and Environmental Sciences , Zhejiang Normal University , Jinhua 321004 , China
| | - Xiaoqin Xu
- College of Geography and Environmental Sciences , Zhejiang Normal University , Jinhua 321004 , China
| | - Liming Geng
- College of Geography and Environmental Sciences , Zhejiang Normal University , Jinhua 321004 , China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences , Zhejiang Normal University , Jinhua 321004 , China
| | - Jiale Wen
- College of Geography and Environmental Sciences , Zhejiang Normal University , Jinhua 321004 , China
| | - Zhiguo Wang
- Institute of Ageing Research, School of Medicine , Hangzhou Normal University , Hangzhou 311121 , China
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Dunnick JK, Shockley KR, Morgan DL, Travlos G, Gerrish KE, Ton TV, Wilson RE, Brar SS, Brix AE, Waidyanatha S, Mutlu E, Pandiri AR. Hepatic Transcriptomic Patterns in the Neonatal Rat After Pentabromodiphenyl Ether Exposure. Toxicol Pathol 2020; 48:338-349. [PMID: 31826744 PMCID: PMC7596650 DOI: 10.1177/0192623319888433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human exposure to pentabromodiphenyl ether (PBDE) mixture (DE-71) and its PBDE-47 congener can occur both in utero and during lactation. Here, we tested the hypothesis that PBDE-induced neonatal hepatic transcriptomic alterations in Wistar Han rat pups can inform on potential toxicity and carcinogenicity after longer term PBDE exposures. Wistar Han rat dams were exposed to either DE-71 or PBDE-47 daily from gestation day (GD 6) through postnatal day 4 (PND 4). Total plasma thyroxine (T4) was decreased in PND 4 pups. In liver, transcripts for CYPs and conjugation enzymes, Nrf2, and ABC transporters were upregulated. In general, the hepatic transcriptomic alterations after exposure to DE-71 or PBDE-47 were similar and provided early indicators of oxidative stress and metabolic alterations, key characteristics of toxicity processes. The transcriptional benchmark dose lower confidence limits of the most sensitive biological processes were lower for PBDE-47 than for the PBDE mixture. Neonatal rat liver transcriptomic data provide early indicators on molecular pathway alterations that may lead to toxicity and/or carcinogenicity if the exposures continue for longer durations. These early toxicogenomic indicators may be used to help prioritize chemicals for a more complete toxicity and cancer risk evaluation.
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Affiliation(s)
- J. K. Dunnick
- Toxicology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - K. R. Shockley
- Biostatistics & Computational Biology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - D. L. Morgan
- Toxicology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - G. Travlos
- Cellular & Molecular Pathology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - K. E. Gerrish
- Molecular Genomics Core, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - T. V. Ton
- Cellular & Molecular Pathology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - R. E. Wilson
- Cellular & Molecular Pathology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - S. S. Brar
- Cellular & Molecular Pathology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - A. E. Brix
- EPL, Inc., Research Triangle Park, North Carolina
| | - S. Waidyanatha
- Program Operations Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - E. Mutlu
- Program Operations Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - A. R. Pandiri
- Cellular & Molecular Pathology Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
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Zhang M, Guo W, Wei J, Shi J, Zhang J, Ge H, Tao H, Liu X, Hu Q, Cai Z. Determination of newly synthesized dihydroxylated polybrominated diphenyl ethers in sea fish by gas chromatography-tandem mass spectrometry. CHEMOSPHERE 2020; 240:124878. [PMID: 31563719 DOI: 10.1016/j.chemosphere.2019.124878] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/14/2019] [Accepted: 09/14/2019] [Indexed: 06/10/2023]
Abstract
Dihydroxylated polybrominated diphenyl ethers (diOH-PBDEs) can be natural products of marine organisms or the metabolites of PBDEs. The optimal determination method and concentration of diOH-PBDEs in seafood are unknown due to a lack of commercially available standards. In the present study, diOH-PBDEs were synthesized, and an efficient measurement method for OH-PBDEs and diOH-PBDEs in sea fish muscle samples, including extraction, clean-up and gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis, was established. Pressurized liquid extraction (PLE) followed by partitioning with a KOH solution and florisil cartridge clean-up proved to be a reliable and robust method for detecting all OH-PBDEs/diOH-PBDEs. GC-MS/MS with an electron ionization (EI) source analysis was a sensitive analytical instrument for OH-PBDEs/diOH-PBDEs. The recovery using this method ranged from 19% to 101%, 28%-88% and 42%-90% for 10 ng, 20 ng and 40 ng spiking levels, respectively. The equipment detection limits (EDLs) were in the range of 0.31-2.78 pg/μL, and the limits of detection (LOD) for the method were in the range of 5.07-38.74 pg/g wet weight. Concentrations of diOH-PBDEs in the marine fish muscle samples were in the range of 32.43-1528.63 pg/g wet weight. Similar compositions of OH-PBDEs/diOH-PBDEs were found within the same family of marine fish.
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Affiliation(s)
- Mengtao Zhang
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China; China State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, China
| | - Wei Guo
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Juntong Wei
- China State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, China
| | - Jianghong Shi
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Jiawei Zhang
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Hui Ge
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Huanyu Tao
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xiaowei Liu
- Hefei University of Technology (Xuancheng Campus) Xuancheng, China
| | - Qing Hu
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Zongwei Cai
- China State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, China.
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Fu Z, Yang L, Sun D, Qu Z, Zhao Y, Gao J, Wang Y. Coupled electron and proton transfer in the piperidine drug metabolism pathway by the active species of cytochromes P450. Dalton Trans 2020; 49:11099-11107. [DOI: 10.1039/c9dt03056e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
KS-DFT and MSDFT studies reveal a novel CEPT step that triggers ring contraction of piperidines by P450.
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Affiliation(s)
- Zhiqiang Fu
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE)
- School of Environmental Science and Technology
- Dalian University of Technology
- Dalian 116024
- China
| | - Lili Yang
- Laboratory of Theoretical and Computational Chemistry
- Institute of Theoretical Chemistry
- Jilin University
- Changchun 130023
- China
| | - Dongru Sun
- Institute of Drug Discovery Technology
- Ningbo University
- Ningbo 315211
- China
| | - Zexing Qu
- Laboratory of Theoretical and Computational Chemistry
- Institute of Theoretical Chemistry
- Jilin University
- Changchun 130023
- China
| | - Yufen Zhao
- Institute of Drug Discovery Technology
- Ningbo University
- Ningbo 315211
- China
| | - Jiali Gao
- Department of Chemistry and Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
- Institute of Systems and Physical Biology
| | - Yong Wang
- Institute of Drug Discovery Technology
- Ningbo University
- Ningbo 315211
- China
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Sousa J, Pinto da Silva L. Modelling the absorption properties of polycyclic aromatic hydrocarbons and derivatives over three European cities by TD-DFT calculations. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 695:133881. [PMID: 31422327 DOI: 10.1016/j.scitotenv.2019.133881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 08/01/2019] [Accepted: 08/10/2019] [Indexed: 06/10/2023]
Abstract
While brown carbon is a strongly-light-absorbing type of organic aerosol that is capable of significant regional radiative forcing, it has been neglected from climate models, which results in differences between model predictions and measured data. This also results from uncertainty regarding the relationship between the chemical composition of brown carbon and its optical properties. Herein, here was utilized a time-dependent density functional theory (TD-DFT) approach to model the "real-world" absorption of thirty polycyclic aromatic hydrocarbons (PAHs) and twenty-five derivatives (ten nitro-PAHs and fifteen oxygenated-PAHs) present in the atmosphere over three Southern European cities (Porto, Florence and Athens). These data were corrected both for "real-world" experimental concentration of these molecules over these cities, and for their theoretical fluorescence yield. These results indicate that the absorption of the molecules more relevant for climate forcing are at ~330, ~360 and ~440 nm. Furthermore, the absorption is explained mainly by PAH and oxygenated-PAH molecules, while nitro-PAHs provide only negligible contributions. Porto should be the city to be most affected by radiative forcing induced by these molecules, while Florence and Athens appear to be similarly affected. Finally, these models also demonstrate that absorption at ~330 nm is explained by both PAH and oxygenated-PAH molecules, while absorption at ~360 and ~440 nm is only attributed to oxygenated-PAHs. More specifically, from the fifty-five studied molecules, only coronene (a PAH), 1,8-naphthalic anhydride, 6-H-benzo[cd]pyrene-6-one and 7H-benz[de]anthracence-7-one (three oxygenated-PAHs) provide relevant contributions to radiative forcing.
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Affiliation(s)
- João Sousa
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Luís Pinto da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal.
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Poston RG, Saha RN. Epigenetic Effects of Polybrominated Diphenyl Ethers on Human Health. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16152703. [PMID: 31362383 PMCID: PMC6695782 DOI: 10.3390/ijerph16152703] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/15/2019] [Accepted: 07/24/2019] [Indexed: 12/15/2022]
Abstract
Disruption of epigenetic regulation by environmental toxins is an emerging area of focus for understanding the latter's impact on human health. Polybrominated diphenyl ethers (PBDEs), one such group of toxins, are an environmentally pervasive class of brominated flame retardants that have been extensively used as coatings on a wide range of consumer products. Their environmental stability, propensity for bioaccumulation, and known links to adverse health effects have evoked extensive research to characterize underlying biological mechanisms of toxicity. Of particular concern is the growing body of evidence correlating human exposure levels to behavioral deficits related to neurodevelopmental disorders. The developing nervous system is particularly sensitive to influence by environmental signals, including dysregulation by toxins. Several major modes of actions have been identified, but a clear understanding of how observed effects relate to negative impacts on human health has not been established. Here, we review the current body of evidence for PBDE-induced epigenetic disruptions, including DNA methylation, chromatin dynamics, and non-coding RNA expression while discussing the potential relationship between PBDEs and neurodevelopmental disorders.
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Affiliation(s)
- Robert G Poston
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, CA 95343, USA
| | - Ramendra N Saha
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, CA 95343, USA.
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Zhang M, Shi J, Meng Y, Guo W, Li H, Liu X, Zhang Y, Ge H, Yao M, Hu Q. Occupational exposure characteristics and health risk of PBDEs at different domestic e-waste recycling workshops in China. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 174:532-539. [PMID: 30861441 DOI: 10.1016/j.ecoenv.2019.03.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/27/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) contained in electronic waste (e-waste) can be released to indoor environments and cause occupational health hazards during the recycling process. TVs, washing machines, refrigerators and printed wiring boar (PWB) represent the main domestic e-wastes. In this study, concentrations of Σ7PBDEs in air and dust samples from recycling workshops handling these four major types of e-wastes were measured, and the occupational exposure risk for workers at the corresponding workshops was evaluated. Concentrations of Σ7PBDEs in air and dust were within the ranges of 55.28-369.66 ng/m3 and 158.07-669.81 μg/g, respectively. The highest concentration of Σ7PBDEs in air was detected in the TV recycling workshop, while the refrigerator recycling workshop had the highest level of Σ7PBDEs in dust. The workers at these two e-waste recycling workshops were the most substantially exposed to BDE-209, which accounted for more than 85% of Σ7PBDEs in both air and dust. Compared to other e-waste recycling workshops, the workers at the PWB recycling workshop were also more exposed to BDE-47 and BDE-99. Occupational exposure levels for inhalation and dust ingestion were within the ranges of 3939 pg/kg/d to 26,271 pg/kg/d and 104,945 pg/kg/d to 444,694 pg/kg/d, respectively. The hazard quotient (HQ) values were calculated based on the RfDs provided by the EPA. Total HQ levels of inhalation exposure and dust ingestion were less than 0.222. The results of the HQ indicated that no adverse health effects were expected for workers in these workshops; however, the exposure risk of workers in the PWB recycling workshop (HQ=0.222) was higher than that in other e-waste recycling workshops (HQ=0.022-0.072). At the PWB recycling workshop, BDE-47 and BDE-99 caused the main occupational exposure risk to the workers, while s in the recycling plants handling other types of domestic e-waste BDE-209 was the major contributor to the risk faced by the workers.
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Affiliation(s)
- Mengtao Zhang
- The Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Jianghong Shi
- The Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China; School of Environment, Beijing Normal University, Beijing, China.
| | - Yaobin Meng
- Academy of Disaster Reduction and Emergency Management, Beijing Normal University, Beijing, China
| | - Wei Guo
- The Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
| | - Huiyuan Li
- School of Environment, Beijing Normal University, Beijing, China
| | - Xiaowei Liu
- Hefei University of Technology (Xuancheng Campus) Xuancheng, China
| | - Yang Zhang
- The Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Hui Ge
- The Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Min Yao
- Jiangsu Provincial Academy of Environmental Science, Nanjing, China
| | - Qing Hu
- The Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
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Habibul N, Chen JJ, Hu YY, Hu Y, Yin H, Sheng GP, Yu HQ. Uptake, accumulation and metabolization of 1-butyl-3-methylimidazolium bromide by ryegrass from water: Prospects for phytoremediation. WATER RESEARCH 2019; 156:82-91. [PMID: 30904713 DOI: 10.1016/j.watres.2019.03.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 06/09/2023]
Abstract
The unique properties of ionic liquids make them attractive for a wide range of industrial applications, which makes it easy to be released into the environment and cause water or soil pollution. Phytoremediation of organic contaminants is a safe and important process for removing persistent pollutants from the environment. However, due to they are very chemically stable and potentially toxic to plants, whether they can be removed, assimilated and metabolized by plants remains unknown during phytoremediation process. In this study, ryegrass, Lolium perenne L., was used for imidazolium ionic liquid (1-butyl-3-methylimidazolium bromide, [C4mim]+) removal from water. The results show that [C4mim]+ could be taken up, accumulated and metabolized by plants in vivo with a high removal efficiency. Most of the [C4mim]+ was accumulated in the root tissue, with the root concentration fraction factors ranging from 4.9 to 51.5. Two hydroxylated metabolites 1-(4-hydroxybutyl)-3-methylimidazolium, and 1-(n-butyl)-3-(hydroxymethyl)-imidazolium, and two secondary metabolites were detected in the ryegrass after [C4mim]+ uptake. The metabolic mechanism was clarified using density functional theory calculations. Furthermore, [C4mim]+ at a high concentration was found to be high toxic to inhibit the growth of ryegrass markedly. In response, some oxidative stress was observed in the metabolic process, as indicated by increasing of catalase, super dismutase and peroxidase activities. Our results suggested that phytoremediation was an efficient technique for ionic liquids treatment from water.
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Affiliation(s)
- Nuzahat Habibul
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science and Technology of China, Hefei, 230026, China; College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830054, China
| | - Jie-Jie Chen
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Yan-Yun Hu
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230026, China
| | - Yi Hu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science and Technology of China, Hefei, 230026, China
| | - Hao Yin
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230026, China
| | - Guo-Ping Sheng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science and Technology of China, Hefei, 230026, China.
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science and Technology of China, Hefei, 230026, China
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Bao L, Liu W, Li Y, Wang X, Xu F, Yang Z, Yue Y, Zuo C, Zhang Q, Wang W. Carcinogenic Metabolic Activation Process of Naphthalene by the Cytochrome P450 Enzyme 1B1: A Computational Study. Chem Res Toxicol 2019; 32:603-612. [PMID: 30794404 DOI: 10.1021/acs.chemrestox.8b00297] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabolic activation and transformation of naphthalene by the cytochrome P450 enzyme (CYP 1B1) plays an important role in its potential carcinogenicity. The process has been explored by a quantum mechanics/molecular mechanics (QM/MM) computational method. Molecular dynamic simulations were performed to explore the interaction between naphthalene and CYP 1B1. Naphthalene involves α- and β-carbon, the electrophilic addition of which would result in different reaction pathways. Our computational results show that both additions on α- and β-carbon can generate naphthalene 1,2-oxide. The activation barrier for the addition on β-carbon is higher than that for the α-carbon by 2.6 kcal·mol-1, which is possibly caused by the proximity between β-carbon and the iron-oxo group of Cpd I in the system. We also found that naphthalene 1,2-oxide is unstable and the O-C bond cleavage easily occurs via cellular hydronium ion, hydroxyl radical/anion; then it will convert to the potential ultimate carcinogen 1,2-naphthoquinone. The results demonstrate and inform a detailed process of generating naphthalene 1,2-oxide and new predictions for its conversion.
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Affiliation(s)
- Lei Bao
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Wen Liu
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Yanwei Li
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Xueyu Wang
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Fei Xu
- Shenzhen Research Institute of Shandong University , Shenzhen 518057 , People's Republic of China
| | - Zhongyue Yang
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Yue Yue
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Chenpeng Zuo
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Qingzhu Zhang
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
| | - Wenxing Wang
- Environment Research Institute , Shandong University , Qingdao 266237 , People's Republic of China
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Tang W, Chen J, Wang Z, Xie H, Hong H. Deep learning for predicting toxicity of chemicals: a mini review. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2019; 36:252-271. [PMID: 30821199 DOI: 10.1080/10590501.2018.1537563] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Humans and wildlife inhabit a world with panoply of natural and synthetic chemicals. Alarmingly, only a limited number of chemicals have undergone comprehensive toxicological evaluation due to limitations of traditional toxicity testing. High-throughput screening assays provide a higher-speed alternative for conventional toxicity testing. Advancement of high-throughput bioassay technology has greatly increased chemical toxicity data volumes in the past decade, pushing toxicology research into a "big data" era. However, traditional data analysis methods fail to effectively process large data volumes, presenting both a challenge and an opportunity for toxicologists. Deep learning, a machine learning method leveraging deep neural networks (DNNs), is a proven useful tool for building quantitative structure-activity relationship (QSAR) models for toxicity prediction utilizing these new large datasets. In this mini review, a brief technical background on DNNs is provided, and the current state of chemical toxicity prediction models built with DNNs is reviewed. In addition, relevant toxicity data sources are summarized, possible limitations are discussed, and perspectives on DNN utilization in chemical toxicity prediction are given.
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Affiliation(s)
- Weihao Tang
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
| | - Jingwen Chen
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
| | - Zhongyu Wang
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
| | - Hongbin Xie
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
| | - Huixiao Hong
- b National Center for Toxicological Research , U.S. Food and Drug Administration , Jefferson , Arkansas , USA
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Fu Z, Chen J. Xenobiotic Metabolism by Cytochrome P450 Enzymes: Insights Gained from Molecular Simulations. CHALLENGES AND ADVANCES IN COMPUTATIONAL CHEMISTRY AND PHYSICS 2019. [DOI: 10.1007/978-3-030-16443-0_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Zhang Q, Ji S, Chai L, Yang F, Zhao M, Liu W, Schüürmann G, Ji L. Metabolic Mechanism of Aryl Phosphorus Flame Retardants by Cytochromes P450: A Combined Experimental and Computational Study on Triphenyl Phosphate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:14411-14421. [PMID: 30421920 DOI: 10.1021/acs.est.8b03965] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Understanding metabolic mechanisms is critical and remains a difficult task in the risk assessment of emerging pollutants. Triphenyl phosphate (TPHP), a widely used aryl phosphorus flame retardant (aryl-PFR), has been frequently detected in the environment, and its major metabolite was considered as diphenyl phosphate (DPHP). However, knowledge of the mechanism for TPHP leading to DPHP and other metabolites is lacking. Our in vitro study shows that TPHP is metabolized into its diester metabolite DPHP and mono- and dihydroxylated metabolites by cytochromes P450 (CYP) in human liver microsomes, while CYP1A2 and CYP2E1 isoforms are mainly involved in such processes. Molecular docking gives the conformation for TPHP binding with the active species Compound I (an iron IV-oxo heme cation radical) in specific CYP isoforms, showing that the aromatic ring of TPHP is likely to undergo metabolism. Quantum chemical calculations have shown that the dominant reaction channel is the O-addition of Compound I onto the aromatic ring of TPHP, followed by a hydrogen-shuttle mechanism leading to ortho-hydroxy-TPHP as the main monohydroxylated metabolite; the subsequent H-abstraction-OH-rebound reaction acting on ortho-hydroxy-TPHP yields the meta- and ipso-position quinol intermediates, while the former of which can be metabolized into dihydroxy-TPHP by fast protonation, and the latter species needs to go through type-I ipso-substitution and fast protonation to be evolved into DPHP. We envision that the identified mechanisms may give inspiration for studying the metabolism of several other aryl-PFRs by CYP.
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Affiliation(s)
- Quan Zhang
- College of Environment , Zhejiang University of Technology , Hangzhou 310032 , China
| | - Shujing Ji
- College of Environmental and Resource Sciences , Zhejiang University , Hangzhou 310058 , China
| | - Lihong Chai
- College of Environmental and Resource Sciences , Zhejiang University , Hangzhou 310058 , China
| | - Fangxing Yang
- College of Environmental and Resource Sciences , Zhejiang University , Hangzhou 310058 , China
| | - Meirong Zhao
- College of Environment , Zhejiang University of Technology , Hangzhou 310032 , China
| | - Weiping Liu
- College of Environmental and Resource Sciences , Zhejiang University , Hangzhou 310058 , China
| | - Gerrit Schüürmann
- UFZ Department of Ecological Chemistry , Helmholtz Centre for Environmental Research , Permoserstrasse 15 , 04318 Leipzig , Germany
- Institute for Organic Chemistry , Technical University Bergakademie Freiberg , Leipziger Strasse 29 , 09596 Freiberg , Germany
| | - Li Ji
- College of Environmental and Resource Sciences , Zhejiang University , Hangzhou 310058 , China
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Wang R, Tang T, Feng S, Chen X, Dang D, Huang K, Tao X, Yin H, Dang Z, Lu G. Experimental and theoretical investigations on debromination pathways of polybrominated biphenyls (PBBs) under ultraviolet light. CHEMOSPHERE 2018; 212:1-7. [PMID: 30130655 DOI: 10.1016/j.chemosphere.2018.08.063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 07/29/2018] [Accepted: 08/13/2018] [Indexed: 06/08/2023]
Abstract
Polybrominated biphenyls (PBBs) are brominated flame retardants that are widely used in textiles and electronic products. Recently, many researches have been devoted to determining their concentrations in food and in the environment. Yet, their degradation behavior has been less investigated and is not well understood. Here, we have investigated the debromination pathways of PBBs by (UV) light in the case of 2,4,5-tribrominated biphenyl (PBB-29). Our investigation indicates that para-bromine substituent on PBB-29 was preferentially removed. By means of density functional theory (DFT), we found that the energies of the debromination products, the CBr bond length in the excited state (S1), the Mulliken charge of bromine in S1, and the lowest unoccupied molecular orbital (LUMO) in S1 correlated well with the debromination pathways of PBBs. Further, LUMO-based prediction of PBB debromination pathways in S1 suggests that the bromine substituent on all brominated positions (i.e. ortho-, meta- and para-) can be preferentially removed, as the debromination sequence is not based on the brominated position but on the specific brominated arrangement pattern. In addition, reductive debromination preferentially occurs on the benzene ring that has the highest number of bromine substituents. This study provided useful descriptors to predict the debromination pathways of PBBs, and the theoretical result greatly improve our understanding of photolytic debromination of PBBs.
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Affiliation(s)
- Rui Wang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Ting Tang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Siyuan Feng
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xingwei Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
| | - Dai Dang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
| | - Kaibo Huang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xueqin Tao
- College of Environmental Science and Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
| | - Hua Yin
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Guining Lu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China.
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Fu Z, Chen J, Wang Y, Hong H, Xie H. Quantum chemical simulations revealed the toxicokinetic mechanisms of organic phosphorus flame retardants catalyzed by P450 enzymes. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2018; 36:272-291. [PMID: 30457030 DOI: 10.1080/10590501.2018.1537564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The metabolic fate and toxicokinetics of organic phosphorus flame retardants catalyzed by cytochrome P450 enzymes (CYPs) are here investigated by in silico simulations, leveraging an active center model to mimic the CYPs, triphenyl phosphate (TPHP), tris(2-butoxyethyl) phosphate and tris(1,3-dichloro-2-propyl) phosphate as substrates. Our calculations elucidated key main pathways and predicted products, which were corroborated by current in vitro data. Results showed that alkyl OPFRs are eliminated faster than aryl and halogenated alkyl-substituted OPFRs. In addition, we discovered a proton shuttle pathway for aryl hydroxylation of TPHP and P = O bond-assisted H-transfer mechanisms (rather than nonenzymatic hydrolysis) that lead to O-dealkylation/dearylation of phosphotriesters.
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Affiliation(s)
- Zhiqiang Fu
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
| | - Jingwen Chen
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
| | - Yong Wang
- b State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics (LICP) , Chinese Academy of Sciences , Lanzhou , China
| | - Huixiao Hong
- c National Center for Toxicological Research , U.S. Food and Drug Administration , Jefferson , Arkansas , USA
| | - Hongbin Xie
- a Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian , China
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Ma G, Yu H, Xu T, Wei X, Chen J, Lin H, Schüürmann G. Computational Insight into the Activation Mechanism of Carcinogenic N'-Nitrosonornicotine (NNN) Catalyzed by Cytochrome P450. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:11838-11847. [PMID: 30209943 DOI: 10.1021/acs.est.8b02795] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Tobacco-specific N'-nitrosonornicotine (NNN), a genotoxic nitrosamine classified as Group 1 carcinogen, is also present in atmospheric particulate matter and has even been detected as a new disinfection byproduct in wastewaters. NNN generally requires metabolic activation by cytochrome P450 enzymes to exert its genotoxicity, but the respective biotransformation pathways have not been described in detail. In this work, we performed density functional theory (DFT) calculations to unravel possible NNN activation pathways including α-hydroxylation, β-hydroxylation, pyridine N-oxidation, and norcotinine formation. The results reveal an initial rate-determining Hα-atom abstraction step for α-hydroxylation, followed by an unexpected kinetic competition between denitrosation and OH rebound, leading to ( iso-)myosmine as a detoxified product and α-hydroxyNNNs as the precursor of carcinogenic diazohydroxides, respectively. Further detoxification routes are given by β-hydroxylation with relative high reaction barrier and N-oxidation with comparable barrier to the toxifying α-hydroxylation. Moreover, we show for the first time how norcotinine can be generated as a minor NNN metabolite that is formed from iso-myosmine through a unique porphyrin-assisted H atom 1,2-transfer mechanism. These results demonstrate that the carcinogenic potential of NNN is subject to a kinetic competition between activating and deactivating metabolic routes, and identify respective biomarkers to inform about the individual risk associated with NNN exposure.
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Affiliation(s)
- Guangcai Ma
- College of Geography and Environmental Sciences , Zhejiang Normal University , Yingbin Avenue 688 , 321004 , Jinhua , China
| | - Haiying Yu
- College of Geography and Environmental Sciences , Zhejiang Normal University , Yingbin Avenue 688 , 321004 , Jinhua , China
| | - Ting Xu
- College of Geography and Environmental Sciences , Zhejiang Normal University , Yingbin Avenue 688 , 321004 , Jinhua , China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences , Zhejiang Normal University , Yingbin Avenue 688 , 321004 , Jinhua , China
| | - Jianrong Chen
- College of Geography and Environmental Sciences , Zhejiang Normal University , Yingbin Avenue 688 , 321004 , Jinhua , China
| | - Hongjun Lin
- College of Geography and Environmental Sciences , Zhejiang Normal University , Yingbin Avenue 688 , 321004 , Jinhua , China
| | - Gerrit Schüürmann
- UFZ Department of Ecological Chemistry , Helmholtz Centre for Environmental Research , Permoserstrasse 15 , 04318 , Leipzig , Germany
- Institute of Organic Chemistry , Technical University Bergakademie Freiberg , Leipzig Strasse 29 , 09596 Freiberg , Germany
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50
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Zhang YN, Wang J, Chen J, Zhou C, Xie Q. Phototransformation of 2,3-Dibromopropyl-2,4,6-tribromophenyl ether (DPTE) in Natural Waters: Important Roles of Dissolved Organic Matter and Chloride Ion. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:10490-10499. [PMID: 30141914 DOI: 10.1021/acs.est.8b03258] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Novel brominated flame retardants (NBFRs) have become ubiquitous emerging organic pollutants. However, little is known about their transformation in natural waters. In this study, aquatic photochemical behavior of a representative NBFR, 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), was investigated by simulated sunlight irradiation experiment. Results show that DPTE can undergo direct photolysis (apparent quantum yield 0.008 ± 0.001) and hydroxyl radical (·OH) initiated oxidation (second order reaction rate constant 2.4 × 109 M-1·s-1). Dissolved organic matter (DOM) promotes the photodegradation due to generation of excited triplet DOM and ·OH. Two chlorinated intermediates were identified in the photodegradation of DPTE in seawaters. Density functional theory calculation showed that ·Cl or ·Cl2- addition reactions on C-Br sites of the phenyl group and H-abstraction reactions from the propyl group are main reaction pathways of DPTE with the chlorine radicals. The ·Cl or ·Cl2- addition proceeds via a replacement mechanism to form chlorinated intermediates. Environmental half-lives of DPTE relevant with photodegradation are estimated to be 6.5-1153.9 days in waters of the Yellow River estuarine region. This study provides valuable insights into the phototransformation behavior of DPTE in natural waters, which is helpful for persistence assessment of the NBFRs.
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Affiliation(s)
- Ya-Nan Zhang
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment , Northeast Normal University , Changchun 130117 , China
| | - Jieqiong Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Chengzhi Zhou
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Qing Xie
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
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