Abstract：
Over the past decades, the synthetic glucocorticoids (GCs) have been widely used in clinical practice and animal husbandry. Given the health hazard of these toxic residues in food, it is necessary to explore the detailed interaction mechanisms of typical GCs and their main target glucocorticoid receptor (GR). Hence, this work compared the GR binding and agonist activities of typical GCs. Fluorescence polarization assay showed that these GCs were potent ligands of GR. Their GR binding affinities were in the order of methylprednisolone>betamethasone≈prednisolone>dexamethasone, with IC50 values of 1.67, 2.94, 2.95, and 5.58 nM. Additionally, the limits of detection of dexamethasone, betamethasone, prednisolone, and methylprednisolone were 0.32, 0.14, 0.19, and 0.09 μg/kg in fluorescence polarization assay. Reporter gene assay showed that these GCs induced GR transactivation in a dose-dependent manner, confirming their GR agonist activities. Among which, dexamethasone at the concentration of 100 nM produced a maximal induction of more than 11-fold over the blank control. Molecular docking and molecular dynamics simulations suggested that hydrogen-bonding and hydrophobic interactions played an important role in stabilizing the GC-GR-LBD complexes. In summary, this work might help to understand the GR-mediated endocrine disrupting effects of typical GCs.
摘要：
在过去的几十年里，合成糖皮质激素(GCs)已广泛应用于临床和畜牧业。鉴于食品中这些有毒残留物对健康的危害，有必要详细探讨典型GCs与其主要靶点糖皮质激素受体(GR)的相互作用机制。因此，这项工作比较了典型GC的GR结合和激动剂活性。荧光偏振分析表明，这些GC是GR的有效配体。它们的GR结合亲和力顺序为甲泼尼龙>倍他米松≈泼尼松龙>地塞米松，IC50值为1.67、2.94、2.95和5.58nM。此外,地塞米松的检测限，倍他米松,泼尼松龙,甲基强的松龙在荧光偏振试验中分别为0.32、0.14、0.19和0.09μg/kg。报告基因分析表明，这些GCs以剂量依赖的方式诱导GR反式激活，确认其GR激动剂活性。其中,100nM浓度的地塞米松产生的最大诱导超过空白对照的11倍。分子对接和分子动力学模拟表明，氢键和疏水相互作用在稳定GC-GR-LBD复合物中起着重要作用。总之,这项工作可能有助于理解典型GCs的GR介导的内分泌干扰效应。
