An SAR Study on a Class of 6-(Trifluoromethyl)-pyridine Derivatives as RORγt Inverse Agonists

Background: The nuclear retinoic acid-related orphan receptor γt (RORγt) is an important transcription factor in immune cells. Functionally, RORγt plays an important role in promoting the differentiation of T helper 17 cells and regulating the expression of proinflammatory factors, such as interleukin 17. Therefore, RORγt is considered a promising target for the treatment of the autoimmune disorder. Currently, 21 RORγt inverse agonists with various scaffolds have entered clinical trials. Objective: To discover novel and potent RORγt inverse agonists, a series of novel 6-(trifluoromethyl) pyridine derivatives were designed and synthesized. Methods: We designed and synthesized a series of potent RORγt inverse agonists W1~W16 based on VTP-43742. Molecular docking, molecular dynamics (MD) simulation, and MM/GBSA were used to study the structure-activity relationship (SAR) of the derivatives. Results: The biological activity evaluation indicated that the target compounds showed potent RORγt inhibitory activity. The most active compound, W14, exhibited low nanomolar inhibitory activity (IC50 = 7.5 nM) in the luciferase reporter assay, which was superior to the clinical compound VTP-43742. Analysis of the binding mode of W14 demonstrated that the interaction of -CF3 with Leu324, Leu396, and His479 has an important contribution to the binding. Furthermore, W14 broke the H-bond formed by His479 and Tyr502 via a “push-pull” mechanism. Conclusion: Compound W14 could be used as a potential RORγt inverse agonist for further modification.