Further investigation of Paprotrain: Towards the conception of selective and multi-targeted CNS kinase inhibitors

Starting from a known compound, identified as the first inhibitor of the kinesin MKLP-2 and named Paprotrain, we have investigated its reactivity to produce through photochemistry a potent nanomolar inhibitor of the kinase DYRK1A. Using similar and different chemical pathways, we have designed several families of compounds that have been screened on a panel of five protein kinases: CK1δ/ε, CDK5/p25, GSK3α/β, DYRK1A and CLK1, all involved in neurodegenerative disorders such as Alzheimer's disease. We have identified a first group of multi-targeted compounds, a second group of dual inhibitors of DYRK1A & CLK1 and a last group of selective inhibitors of CLK1. Then, our best submicromolar to nanomolar inhibitors were evaluated towards the closest members of the aforementioned kinases: DYRK1B and CLK4, as well as the subfamily CLK2-3. Several compounds appear to be particularly promising for the development of tools in the battle against Alzheimer's disease.