Disruption of Canonical TGF-β/SMAD Signaling Pathway by TSCA High-Priority Phthalate Plasticizers: A Dual-Engine Molecular Docking Analysis

• Mrinmoy Mandal

  Department of Chemistry, School of Basic & Applied Science, Sanskaram University, Patauda-124108, Jhajjar, Haryana, India

• Naveen Kumar

  Department of Zoology, School of Basic & Applied Science, Sanskaram University, Patauda-124108, Jhajjar, Haryana, India

• Pooja Kadyan

  Department of Zoology, Sant Shiromani Shri Sain Bhagat Government College, Jind (126102), Haryana, India

• Sapna Redhu

  Department of Biotechnology, Chaudhary Devi Lal University, Sirsa-125055, India

• Jayendra Kumar Singh

  School of Business, University of Petroleum and Energy Studies, Dehradun-248007, Uttarakhand, India

• Kaushalendra

  Department of Zoology, Pachhunga University College Campus, Mizoram University, Aizawl - 796001, India

• Nisha Yadav

  Department of Chemistry, School of Basic & Applied Science, Sanskaram University, Patauda-124108, Jhajjar, Haryana, India

• Divya Tyagi

  Department of Chemistry, School of Basic & Applied Science, Sanskaram University, Patauda-124108, Jhajjar, Haryana, India

• Vikrant

  Department of Botany, School of Basic & Applied Science, Sanskaram University, Patauda-124108, Jhajjar, Haryana, India

• Varsha Singh

  Department of Zoology, Institute of Science, Banaras Hindu University (BHU), Varanasi, 221005, Uttar Pradesh, India

Uses of Plastic have increased worldwide and phthalate esters - released continuously from plastic matrices due to their non-covalent bonding - are among the most abundantly detected chemical additives in human biomonitoring globally. Seven phthalates are currently designated as High-Priority Substances under active federal risk evaluation by the US EPA under Toxic Substances Control Act (TSCA). Of these, five - di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), diisobutyl phthalate (DIBP), benzyl butyl phthalate (BBP), and dicyclohexyl phthalate (DCP) - were selected based on dominance in environmental detection and biomonitoring data. Despite growing evidence linking phthalates to various diseases, no study has evaluated all five together against a complete signaling pathway spanning membrane, cytoplasmic, and nuclear protein targets. Therefore, dual-engine molecular docking was performed using AutoDock 4 and AutoDock Vina against four resolved TGF-β/SMAD signaling Pathway targets - TGFβRI (3TZM), TGFβRII (5E92), SMAD2 (1DEV), and SMAD3/SMAD4 (1U7F) - the only pathway among 18 studied which have all three cellular compartments. All five showed binding above −6.0 kcal mol⁻¹ at TGFβRI, TGFβRII, and SMAD3/SMAD4 in both engines. Affinity hierarchy was consistent - DCP > BBP > DIBP > DBP > DEHP - across all four targets. At SMAD2, only DCP showed stable binding and remaining four produced no stable/convergent docking pose under the specified conditions. DCP is the least detected yet showed strongest binding - showing environmental prevalence does not predict receptor-level potency. These findings support TSCA cumulative risk assessment and warrant in vitro phosphorylation and SMAD-reporter gene validation, subject to further studies.

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Copyright (c) 2026 Mrinmoy Mandal, Naveen Kumar, Pooja Kadyan, Sapna Redhu, Jayendra Kumar Singh, Kaushalendra, Nisha Yadav, Divya Tyagi, Vikrant, Varsha Singh

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