Details

Autor(en) / Beteiligte

• Chen, Guanhui
• Niu, Xiaolin
• Chen, Yi
• Wang, Mei
• Bi, Yashi
• Gao, Yanpeng
• Ji, Yuemeng
• An, Taicheng

Titel

Estrogenic disruption effects and formation mechanisms of transformation products during photolysis of preservative parabens

Ist Teil von

• The Science of the total environment, 2024-05, Vol.924, p.171608-171608, Article 171608

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• The ubiquitous presence of emerging contaminants (ECs) in the environment and their associated adverse effects has raised concerns about their potential risks. The increased toxicity observed during the environmental transformation of ECs is often linked to the formation of their transformation products (TPs). However, comprehension of their formation mechanisms and contribution to the increased toxicity remains an unresolved challenge. To address this gap, by combining quantum chemical and molecular simulations with photochemical experiments in water, this study investigated the formation of TPs and their molecular interactions related to estrogenic effect using the photochemical degradation of benzylparaben (BZP) preservative as a representative example. A non-targeted analysis was carried out and three previously unknown TPs were identified during the transformation of BZP. Noteworthy, two of these novel TPs, namely oligomers BZP-o-phenol and BZP-m-phenol, exhibited higher estrogenic activities compared to the parent BZP. Their IC50 values of 0.26 and 0.50 μM, respectively, were found to be lower than that of the parent BZP (6.42 μM). The binding free energies (ΔGbind) of BZP-o-phenol and BZP-m-phenol (−29.71 to −23.28 kcal·mol−1) were lower than that of the parent BZP (−20.86 kcal·mol−1), confirming their stronger binding affinities toward the estrogen receptor (ER) α-ligand binding domain. Subsequent analysis unveiled that these hydrophobic residues contributed most favorably to ER binding, with van der Waals interactions playing a significant role. In-depth examination of the formation mechanisms indicated that these toxic TPs primarily originated from the successive cleavage of ester bonds (OCH2C6H5 and COO group), followed by their combination with BZP*. This study provides valuable insight into the mechanisms underlying the formation of toxic TPs and their binding interactions causing the endocrine-disrupting effects. It offers a crucial framework for elucidating the toxicological patterns of ECs with similar structures. [Display omitted] •Innovated a potent toxicity evaluation method for unknown transformation products•Identified three unknown transformation products during BZP photodegradation•Discovered two oligomeric products with significantly elevated estrogenic activity•Emphasized the crucial role of hydrophobic residues in the estrogenic products•Estrogenic oligomer formation through successive ester bond cleavages in parabens