Abstract：
Pentachlorophenol (PCP) is a widely used pesticide. However, whether PCP and its metabolite chloranil have endocrine-disrupting effects by inhibiting placental 3β-hydroxysteroid dehydrogenase 1 (3β-HSD1) remains unclear. The study used in vitro assays with human and rat placental microsomes to measure 3β-HSD activity as well as human JAr cells to evaluate progesterone production. The results showed that PCP exhibited moderate inhibition of human 3β-HSD1, with an IC50 value of 29.83 μM and displayed mixed inhibition in terms of mode of action. Conversely, chloranil proved to be a potent inhibitor, demonstrating an IC50 value of 147 nM, and displaying a mixed mode of action. PCP significantly decreased progesterone production by JAr cells at 50 μM, while chloranil markedly reduced progesterone production at ≥1 μM. Interestingly, PCP and chloranil moderately inhibited rat placental homolog 3β-HSD4, with IC50 values of 27.94 and 23.42 μM, respectively. Dithiothreitol (DTT) alone significantly increased human 3β-HSD1 activity. Chloranil not PCP mediated inhibition of human 3β-HSD1 activity was completely reversed by DTT and that of rat 3β-HSD4 was partially reversed by DTT. Docking analysis revealed that both PCP and chloranil can bind to the catalytic domain of 3β-HSDs. The difference in the amino acid residue Cys83 in human 3β-HSD1 may explain why chloranil is a potent inhibitor through its interaction with the cysteine residue of human 3β-HSD1. In conclusion, PCP is metabolically activated to chloranil as a potent inhibitor of human 3β-HSD1.
摘要：
五氯苯酚（PCP）是一种广泛使用的农药。然而,PCP及其代谢产物氯醌是否通过抑制胎盘3β-羟基类固醇脱氢酶1（3β-HSD1）而具有内分泌干扰作用尚不清楚。该研究使用人和大鼠胎盘微粒体的体外测定法来测量3β-HSD活性以及人JAr细胞来评估孕酮的产生。结果表明，PCP对人3β-HSD1表现出中度抑制作用，IC50值为29.83μM，并在作用方式上表现出混合抑制作用。相反，氯醌被证明是一种有效的抑制剂，IC50值为147nM，并显示混合操作模式。PCP在50μM时显著降低JAr细胞产生的孕酮，氯醌在≥1μM时显著降低孕酮产量。有趣的是,五氯苯酚和氯苯胺适度抑制大鼠胎盘同源物3β-HSD4，IC50值分别为27.94和23.42μM，分别。单独的二硫苏糖醇(DTT)显著增加人3β-HSD1活性。DTT完全逆转了非PCP介导的对人3β-HSD1活性的抑制作用，而DTT则部分逆转了大鼠3β-HSD4的抑制作用。对接分析显示，PCP和氯醌均可与3β-HSD的催化结构域结合。人3β-HSD1中氨基酸残基Cys83的差异可以解释为什么氯醌通过与人3β-HSD1的半胱氨酸残基相互作用而成为有效的抑制剂。总之,PCP作为人3β-HSD1的有效抑制剂被代谢激活为氯醌。
