Abstract：
Microbial indoles have been demonstrated as selective or dual agonists and ligands of the pregnane X receptor (PXR) and aryl hydrocarbon receptor (AhR). However, structural determinants of microbial indoles selectivity towards both receptors remain elusive. Here, we studied the effects of existing and newly synthesized derivatives of indole microbial metabolite tryptamine on the activity of AhR and PXR receptors. We show that the elongation of indolyl-3-alkaneamine chain, indole N-methylation and conversion of indolyl-3-alkaneamines to oleamides resulted in a major increase of PXR activity and in parallel loss of AhR activity. Using reporter gene assays, RT-PCR and TR-FRET techniques, we have characterized in detail the activation of PXR by novel indolyl-3-alkanyl-oleamides, 1-methyltryptamine and 1-methyltryptamine-acetamide. As a proof of concept, we demonstrated anti-inflammatory and epithelial barrier-protective activity of lead derivatives in intestinal Caco-2 cells, employing the measurement of expression of pro-inflammatory chemokines, tight junction genes, trans-epithelial electric resistance TEER, and dextran-FITC permeability assay. In conclusion, we show that a subtle chemical modifications of simple microbial indole metabolite tryptamine, leads to substantial changes in AhR and PXR agonist activities.
摘要：
微生物吲哚已被证明是孕烷X受体（PXR）和芳烃受体（AhR）的选择性或双重激动剂和配体。然而,微生物吲哚对两种受体的选择性的结构决定因素仍然难以捉摸。这里,我们研究了吲哚微生物代谢产物色胺的现有和新合成衍生物对AhR和PXR受体活性的影响。我们证明吲哚基-3-链烷胺链的伸长，吲哚N-甲基化和吲哚基-3-链烷胺向油酰胺的转化导致PXR活性的显着增加和AhR活性的平行丧失。使用报告基因测定，RT-PCR和TR-FRET技术，我们已经详细地表征了通过新型吲哚基-3-烷酰基-油酰胺活化PXR，1-甲基色胺和1-甲基色胺-乙酰胺。作为概念的证明，我们证明了铅衍生物在肠道Caco-2细胞中的抗炎和上皮屏障保护活性，采用促炎趋化因子表达的测量，紧密连接基因，跨上皮电阻TEER,和葡聚糖-FITC通透性测定。总之,我们表明，一个微妙的化学修饰简单的微生物吲哚代谢物色胺，导致AhR和PXR激动剂活性发生实质性变化。
