This invention belongs to the pharmaceutical field, specifically relating to novel compounds that inhibit Th17
cell differentiation and their applications. Specifically, this invention provides various novel compounds, their tautomers, stereoisomers,
isotope markers, hydrates, solvates, pharmaceutically acceptable salts, or prodrugs, which possess
biological activity in inhibiting the differentiation of CD4+ T cells into Th17 cells and can be used for the prevention and / or treatment of Th17
cell-related autoimmune deficiency diseases (especially
multiple sclerosis). The various compounds of this invention have novel structures and excellent
biological activity, making them ideal candidate
drug compounds for the treatment of MS.