Phthalate monoesters are important metabolites of phthalate esters (PAEs) which have been extensively utilized in industry. This study aims to investigate the inhibition of phthalate monoesters on the activity of various isoforms of UDP-glucuronosyltransferases (UGTs), trying to elucidate the toxicity mechanism of environmental endocrine disruptors from the new perspectives. In vitro recombinant UGTs-catalyzed glucuronidation of 4-methylumbelliferone (4-MU) was employed to evaluate 8 kinds of phthalate monoesters on 11 sorts of main human UGT isoforms. 100 μM phthalate monoesters exhibited negligible inhibition towards the activity of UGT1A1, UGT1A3, UGT1A6, UGT1A8, UGT1A10, UGT2B4, UGT2B7, UGT2B15 and UGT2B17. The activity of UGT1A7 was strongly inhibited by monoethylhexyl phthalate (MEHP), but slightly inhibited by all the other phthalate monoesters. UGT1A9 was broadly inhibited by monobenzyl phthalate (MBZP), monocyclohexyl phthalate (MCHP), MEHP, monohexyl phthalate (MHP) and monooctyl phthalate (MOP), respectively. MEHP exhibited competitive inhibition towards UGT1A7, and MBZP, MCHP, MEHP, MHP and MOP showed competitive inhibition towards UGT1A9. The inhibition kinetic parameters (K) were calculated to be 11.25 μM for MEHP-UGT1A7, and 2.13, 0.09, 1.17, 7.47, 0.16 μM for MBZP-UGT1A9, MCHP-UGT1A9, MEHP-UGT1A9, MHP-UGT1A9, MOP-UGT1A9, respectively. Molecular docking indicated that both hydrogen bonds formation and hydrophobic interactions significantly contributed to the interaction between phthalate monoesters and UGT isoforms. All these information will be beneficial for understanding the adverse effects of PAEs.
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http://dx.doi.org/10.1016/j.chemosphere.2018.01.010 | DOI Listing |
Structure
November 2024
Department of Biosciences and Bioengineering, IIT Roorkee, Roorkee, Uttarakhand 247667, India. Electronic address:
Phthalate diesters are important pollutants and act as endocrine disruptors. While certain bacterial esterases have been identified for phthalate diesters degradation to monoesters, their structural and mechanistic characteristics remain largely unexplored. Here, we highlight the potential of the thermostable and pH-tolerant EstS1 esterase from Sulfobacillus acidophilus DSM10332 to degrade high molecular weight bis(2-ethylhexyl) phthalate (DEHP) by combining biophysical and biochemical approaches along with high-resolution EstS1 crystal structures of the apo form and with bound substrates, products, and their analogs to elucidate its mechanism.
View Article and Find Full Text PDFEcotoxicol Environ Saf
December 2024
Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China; College of New Energy and Environment, Jilin University, Changchun 130012, China.
The reproductive age is a crucial stage for women to bear offspring. However, reproductive-aged women are simultaneously exposed to various phthalates, which may pose a threat to their reproductive health. This study employed generalized linear regression and weighted quantile sum (WQS) regression to explore the associations between monoesters of phthalates (MPAEs) and sex hormones in 913 reproductive-aged women in the National Health and Nutrition Examination Survey.
View Article and Find Full Text PDFJ Environ Manage
December 2024
College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China; Laboratory of Embryo Biotechnology, College of Life Science, Northeast Agricultural University, Harbin, 150030, China. Electronic address:
Mono-2-ethylhexyl phthalate (MEHP) is the major biologically active metabolite of Di(2-ethylhexyl) phthalate (DEHP). This MEHP mono-ester metabolite can be transported through the bloodstream into tissues such as the liver, kidneys, fat, and testes and cause corresponding damage. Resveratrol (RSV) has anti-inflammatory, antioxidant, and detoxification characteristics.
View Article and Find Full Text PDFReprod Toxicol
December 2024
Competence Centre on Health Technologies, Tartu, Estonia; Department of Obstetrics and Gynaecology, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia; Division of Obstetrics and Gynaecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden; Department of Gynaecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden.
Phthalate monoesters have been identified as endocrine disruptors in a variety of models, yet understanding of their exact mechanisms of action and molecular targets in cells remains incomplete. Here, we set to determine whether epidemiologically relevant mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) can affect biological processes by altering cell plasma membrane fluidity or formation of cell-cell contacts. As a model system, we chose endometrial stromal cell lines, one of which was previously used in a transcriptomic study with MEHHP or MEHHP-containing mixtures.
View Article and Find Full Text PDFToxicol Sci
November 2024
Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07103, United States.
Phthalates are a class of known endocrine-disrupting chemicals that are found in common everyday products. Several studies associate phthalate exposure with detrimental effects on ovarian function, including growth and development of the follicle and production of steroid hormones. We hypothesized that dysregulation of the ovary by phthalates may be mediated by phthalate toxicity towards granulosa cells, a major cell type in ovarian follicles responsible for key steps of hormone production and nourishing the developing oocyte.
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