Discovery and structural optimization of 4-（ 4-（ benzyloxy）p henyl）-3,4-dihyd ropyrimidin-2（1H ）- ones as RORc inverse agonists

Aim： Retinoic acid receptor-related orphan nuclear receptors （RORs） are orphan nuclear receptors that show constitutive activity in the absence of ligands. Among 3 subtypes of RORs, RORc is a promising therapeutic target for the treatment of Th17-mediated autoimmune diseases. Here, we report novel RORc inverse agonists discovered through structure-based drug design. Methods： Based on the structure of compound 8, a previously described agonist of RORa, a series of 4-（4-（benzyloxy）phenyl）-3,4- dihydropyrimidin-2（1H）-one derivatives were designed and synthesized. The interaction between the compounds and RORc was detected at molecular level using AlphaScreen assay. The compounds were further examined in 293T cells transfected with RORc and luciferase reporter gene. Thermal stability shift assay was used to evaluate the effects of the compounds on protein stability. Results： A total of 27 derivatives were designed and synthesized. Among them, the compound 22b was identified as the most potent RORc inverse agonist. Its IC50 values were 2.39 μmol/L in AlphaScreen assay, and 0.82 μmol/L in inhibition of the cell-based luciferase reporter activity. Furthermore, the compound 22b displayed a 120-fold selectivity for RORc over other nuclear receptors. Moreover, a molecular docking study showed that the structure-activity relationship was consistent with the binding mode of compound 22b in RORc. Conclusion： 4-（4-（Benzyloxy）phenyl）-3,4-dihydropyrimidin-2（1H）-one derivatives are promising candidates for the treatment of Th17- mediated autoimmune diseases, such as rheumatoid arthritis, psoriasis, and multiple sclerosis.