Caging Bioactive Triarylimidazoles: An Approach to Create Visible Light-Activatable Drugs

Imidazoles are crucial structural components in a variety of small-molecule inhibitors designed to target different kinases in anticancer treatment. However, the effectiveness of such inhibitors is often hampered by nonspecific effects and the development of resistance. Photopharmacology provides a compelling solution by enabling external control over drug activity with spatiotemporal precision. Herein, we introduce a novel strategy for caging bioactive triarylimidazole-based drug molecules. This approach involves introducing a dialkylamino group as a photoremovable group on the carbon atom of the imidazole ring, which intrinsically modulates the core structure from planar imidazole to tetrahedral 2H-imidazole, enabling the caged compound to be selectively uncaged upon visible light exposure. We applied this innovative caging technique to SB431542, a triarylimidazole-based small-molecule inhibitor that targets the pivotal TGF-β signaling pathway, the dysregulation of which is linked to several human diseases, including cancer. Our results demonstrated the selective inhibition of human breast cancer cell migration in vitro upon light activation, highlighting the potential of our approach to transform triarylimidazole-based drug molecules into visible light-activatable drugs, thereby facilitating spatiotemporal regulation of their pharmacological activity.