ABSTRACT
The interest of research groups and pharmaceutical companies to discover novel GSK-3ß inhibitors has increased over the years considering the involvement of this enzyme in many pathophysiological processes and diseases. Along this line, we recently reported on 1H-indazole-3-carboxamide (INDZ) derivatives 1-6, showing good GSK-3ß inhibition activity. However, they suffered from generally poor central nervous system (CNS) permeability. Here, we describe the design, synthesis, and in vitro characterization of novel imidazo[1,5-a]pyridine-1-carboxamide (IMID 1) and imidazo[1,5-a]pyridine-3-carboxamide (IMID 2) compounds (7-18) to overcome such liability. In detail, structure-based approaches and fine-tuning of physicochemical properties guided the design of derivatives 7-18 resulting in ameliorated absorption, distribution, metabolism, and excretion (ADME) properties. A crystal structure of 16 in complex with GSK-3ß enzyme (PDB entry 6Y9S) confirmed the in silico models. Despite the nanomolar inhibition activity, the new core compounds showed a reduction in potency with respect to INDZ derivatives 1-6. In this context, Molecular Dynamics (MD) and Quantum Mechanics (QM) based approaches along with NMR investigation helped to rationalize the observed structure activity relationship (SAR). With these findings, the key role of the acidic hydrogen of the central core for a tight interaction within the ATP pocket of the enzyme reflecting in good GSK-3ß affinity was demonstrated.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Glycogen Synthase Kinase 3 beta/antagonists & inhibitors , Imidazoles/chemical synthesis , Pyridines/chemistry , Animals , Binding Sites , Crystallography, X-Ray , Dogs , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Glycogen Synthase Kinase 3 beta/chemistry , Imidazoles/chemistry , Imidazoles/pharmacology , Madin Darby Canine Kidney Cells , Molecular Dynamics Simulation , Molecular Structure , Protein Binding , Quantum Theory , Structure-Activity RelationshipABSTRACT
Bipolar disorders still represent a global unmet medical need and pose a requirement for novel effective treatments. In this respect, glycogen synthase kinase 3ß (GSK-3ß) aberrant activity has been linked to the pathophysiology of several disease conditions, including mood disorders. Therefore, the development of GSK-3ß inhibitors with good in vivo efficacy and safety profile associated with high brain exposure is required. Accordingly, we have previously reported the selective indazole-based GSK-3 inhibitor 1, which showed excellent efficacy in a mouse model of mania. Despite the favorable preclinical profile, analog 1 suffered from activity at the hERG ion channel, which prevented its further progression. Herein, we describe our strategy to improve this off-target liability through modulation of physicochemical properties, such as lipophilicity and basicity. These efforts led to the potent inhibitor 14, which possessed reduced hERG affinity, promising in vitro ADME properties, and was very effective in a mood stabilizer in vivo model.
ABSTRACT
Anthocyanidin moiety was obtained by cyclization of a 2-hydroxychalcone prepared by the Heck approach to the synthesis of flavonoids. 1-(3,4-dimethoxyphenyl)-prop-2-en-1-one has been used as a coupling partner along with o-acetoxyiodobenzene in the Heck reaction.
