Halophenylacetamides (HPAcAms) have been identified as a new group of nitrogenous aromatic disinfection byproducts (DBPs) in drinking water, but the toxicity mechanisms associated with HPAcAms remain almost completely unknown. In this work, the cytotoxicity of HPAcAms in human hepatoma (HepG2) cells was evaluated, intracellular oxidative stress/damage levels were analyzed, their binding interactions with antioxidative enzyme were explored, and a quantitative structure-activity relationship (QSAR) model was established. Results indicated that the EC values of HPAcAms ranged from 2353 M to 9780 M, and the isomeric structure as well as the type and number of halogen substitutions could obviously induce the change in the cytotoxicity of HPAcAms. Upon exposure to 2-(3,4-dichlorophenyl)acetamide (3,4-DCPAcAm), various important biomarkers linked to oxidative stress and damage, such as reactive oxygen species, 8‑hydroxy-2-deoxyguanosine, and cell apoptosis, exhibited a significant increase in a dose-dependent manner. Moreover, 3,4-DCPAcAm could directly bind with Cu/Zn-superoxide dismutase and induce the alterations in the structure and activity, and the formation of complexes was predominantly influenced by the van der Waals force and hydrogen bonding. The QSAR model supported that the nucleophilic reactivity as well as the molecular compactness might be highly important in their cytotoxicity mechanisms in HepG2 cells, and 2-(2,4-dibromophenyl)acetamide and 2-(3,4-dibromophenyl)acetamide deserved particular attention in future studies due to the relatively higher predicted cytotoxicity. This study provided the first comprehensive investigation on the cytotoxicity mechanisms of HPAcAm DBPs.

中文翻译：

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饮用水中新出现的卤代苯乙酰胺消毒副产物的细胞毒性：机制和预测

卤代苯乙酰胺 (HPAcAms) 已被确定为饮用水中的一组新的含氮芳香族消毒副产物 (DBP)，但与 HPAcAms 相关的毒性机制仍然几乎完全未知。本工作评估了 HPAcAms 在人肝癌 (HepG2) 细胞中的细胞毒性，分析了细胞内氧化应激/损伤水平，探讨了它们与抗氧化酶的结合相互作用，并建立了定量构效关系 (QSAR) 模型。结果表明，HPAcAms的EC值范围为2353 M~9780 M，异构体结构以及卤素取代的类型和数量可明显引起HPAcAms细胞毒性的变化。接触 2-(3,4-二氯苯基)乙酰胺 (3,4-DCPAcAm) 后，与氧化应激和损伤相关的各种重要生物标志物（例如活性氧、8-羟基-2-脱氧鸟苷和细胞凋亡）表现出以剂量依赖性方式显着增加。此外，3,4-DCPAcAm可以直接与Cu/Zn超氧化物歧化酶结合并引起结构和活性的改变，复合物的形成主要受范德华力和氢键的影响。 QSAR 模型支持亲核反应性和分子致密性可能对其在 HepG2 细胞中的细胞毒性机制非常重要，并且 2-(2,4-二溴苯基)乙酰胺和 2-(3,4-二溴苯基)乙酰胺值得特别关注。由于预测的细胞毒性相对较高，因此在未来的研究中受到关注。这项研究首次对 HPAcAm DBP 的细胞毒性机制进行了全面的研究。