Design, synthesis and structure-activity evaluation of novel 2-pyridone-based inhibitors of alpha-synuclein aggregation with potentially improved BBB permeability

The treatment of Parkinson's disease (PD), the second most common neurodegenerative human disorder, continues to be symptomatic. Development of drugs able to stop or at least slowdown PD progression would benefit several million people worldwide. SynuClean-D is a low molecular weight 2-pyridone-based promising drug candidate that inhibits the aggregation of alpha-synuclein in human cultured cells and prevents degeneration of dopaminergic neurons in a Caenorhabditis elegans model of PD. Improving SynuClean-D pharmacokinetic/ pharmacodynamic properties, performing structure/activity studies and testing its efficacy in mammalian models of PD requires the use of gr-amounts of the compound. However, not enough compound is on sale, and no synthetic route has been reported until now, which hampers the molecule progress towards clinical trials. To circumvent those problems, we describe here an efficient and economical route that enables the synthesis of SynuClean-D with good yields as well as the synthesis of SynuClean-D derivatives. Structure-activity comparison of the new compounds with SynuClean-D reveals the functional groups of the molecule that can be disposed of without activity loss and those that are crucial to interfere with alpha-synuclein aggregation. Several of the derivatives obtained retain the parent's compound excellent in vitro anti-aggregative activity, without compromising its low toxicity. Computational predictions and preliminary testing indicate that the blood brain barrier (BBB) permeability of SynuClean-D is low. Importantly, several of the newly designed and obtained active derivatives are predicted to display good BBB permeability. The synthetic route developed here will facilitate their synthesis for BBB permeability determination and for efficacy testing in mammalian models of PD.