Benzamide Derivatives of Thioacridine as DYRK2 and DYRK3 Dual Inhibitors

DYRK2 has become a promising therapeutic target due to its involvement in various processes, including regulation of protein stability and phosphorylation events related to neurodegenerative diseases and cancers. The thioacridine derivative LDN-192960 has been widely recognized as a potent inhibitor of DYRK2. However, it also inhibits other kinases, such as DYRK3, Haspin, DYRK1A, and CLK1, making it challenging to delineate the biological roles of DYRK2. Herein, a series of benzamide derivatives of the thioacridine LDN-192960 are designed and synthesized to improve selectivity and potency toward DYRK2. Several compounds demonstrate potent inhibition of DYRK2 and DYRK3, with IC₅₀ values in the nanomolar range. Notably, the para-substituted aldehyde derivative 10f exhibits significant selectivity for DYRK2/DYRK3 against its main off-targets DYRK1A, CLK1, and Haspin, thus surpassing the selectivity profile of LDN-192960. Docking studies reveal new interactions between 10f and DYRK2, compared to LDN-192960/DYRK2 cocrystallized structure, and 10f is shown to impair proteasome activity in HEK293 cells. These findings highlight the pharmacophore study of DYRK2/DYRK3 dual inhibitors and present compound 10f as a selective chemical probe for DYRK2 and DYRK3, which might be an essential tool for elucidating the specific biological roles of these kinases and advancing targeted therapeutic applications.