Covalent agonists of PPARγ cause unique receptor conformational changes and behave as selective PPARγ modulators, whereas there are few covalent agonists other than endogenous unsaturated fatty acids metabolites. Previously, we established a cell-based strategy to identify new PPARγ ligands and synthesized a new-type of covalent agonist that possesses the hybrid structure of a plant-derived cinnamic acid derivative and GW9662, a covalent antagonist. Herein, we report six analogues that differ in how the two fragments are linked together. Compounds with a simplified linker showed potent agonistic activity with improved EC50 values (less than 5 nM), indicating that close proximity between the two fragments improves binding affinity. When the position of cinnamic acid moiety was placed at 4′ carbon of aniline ring, PPARγ agonist activity was completely abolished. Docking studies suggested that the activation profile likely depends on interaction with the cavity around helix 3, β-sheet, and Ω-loop region in the ligand-binding domain. Furthermore, a cell-based assay revealed that agonist-type compounds activate PPARγ transcription in a manner dependent on covalent linkage with the Cys285 residue leading to prolonged transactivation. This activation feature reflects pharmacological benefits of covalent drugs, suggesting that these hybrid compounds may serve as potential leads for a new-class of covalent PPARγ ligands.
PPARγ的共价激动剂引起独特的受体构象变化,并表现为选择性PPARγ调节剂,而除内源性不饱和脂肪酸代谢产物外,几乎没有其他共价激动剂。我们先前建立了一种基于细胞的策略来识别新的PPARγ配体,并合成了一种新型的共价激动剂,其具有植物衍生的肉桂酸衍生物和GW9662(一种共价拮抗剂)的混合结构。在这里,我们报告了六种在两个片段如何连接在一起上有所不同的类似物。具有简化连接剂的化合物显示出强大的激动活性,具有改善的EC50值(小于5 nM),表明两个片段之间的密切接近改善了结合亲和力。当肉桂酸部分的位置放置在苯胺环的4'碳上时,PPARγ激动剂活性完全被废除。对接研究表明,激活特性可能取决于与配体结合结构域中螺旋3、β-片和Ω-环区域周围的空腔的相互作用。此外,基于细胞的实验揭示出激动剂型化合物以依赖于与Cys285残基的共价连接导致持续的转录激活的方式激活PPARγ转录。这种激活特性反映了共价药物的药理学益处,表明这些混合物可能作为新型共价PPARγ配体的潜在引物。