Discovery of Dietary Plant Flavonols as Novel Potent Inhibitors Targeting DYRK1A Kinase.

DYRK1A kinase is a critical regulator in cellular signaling pathways and a promising therapeutic target for neurodegenerative diseases, diabetes and cancers. Despite its significance, the development of potent, selective and safe inhibitors remains a significant challenge. Several natural flavonoids have been reported to inhibit DYRK1A by binding in the ATP-binding pocket, exhibiting antidiabetic properties. However, a systematic screening of these structural derivatives remains lacking. In this study, we aimed to expand the pool of flavonoid-based DYRK1A inhibitor candidates for drug development against DYRK1A through targeted screening and structure-based analysis. A focused library of 13 flavonoid derivatives was screened to identify novel DYRK1A inhibitors, revealing eight new flavonol inhibitors with IC(50) values ranging from 149.5 nM to 737.9 nM. Among these, fisetin demonstrated the highest potency with an IC(50) of 149.5 nM, followed by kaempferol (296.3 nM), isorhamnetin (418 nM), morin (478.4 nM), myricetin (633.2 nM) and luteolin (797.8 nM), all exhibiting submicromolar inhibitory activity. Additional novel inhibitors, Apigenin and Kaempferide, also showed effective inhibition. As controls, the previously known inhibitors quercetin and curcumin were evaluated, yielding IC(50) values of 737.9 nM and 2.35 μM, respectively, which validated the assay conditions. To the best of our knowledge, fisetin is the most potent known DYRK1A inhibitor among flavonoids. Cellular assays further demonstrated that the top flavonoid hits induced dose-dependent cytotoxicity and morphological changes in HeLa cells. Structure-activity relationship and molecular simulation analysis revealed that the selected flavonols interact with key residues for DYRK1A inhibition. These results highlight flavonols as a promising scaffold for DYRK1A inhibition and provide valuable natural inhibitor leads for further optimization and therapeutic development.