Here, we report the design and synthesis of pyrimidinyl heterocyclic compounds containing terminal electrophiles as irreversible covalent JAK3 inhibitors that exploit a unique cysteine (Cys909) residue in JAK3. Investigation of the structure-activity relationship utilizing kinase assays resulted in the identification of potent and selective JAK3 inhibitors such as T1, T8, T15, T22, and T29. Among them, T29 was verified as a promising JAK3 irreversible inhibitor that possessed the best bioactivity and selectivity against JAKs and kinases containing a cysteine in the residue analogous to Cys909 in JAK3, suggesting that covalent modification of this Cys residue allowed the identification of a highly selective JAK3 inhibitor. Moreover, T29 also displayed a significant anti-inflammatory effect in ICR mice through the inhibition of increased paw thickness, which is worth further optimization to increase its potency and medicinal properties.
Keywords: Covalent inhibitor; Docking; JAK3; Selectivity; Structure–activity relationship (SAR).