Design, synthesis, and biological evaluation of tetrahydropyrimidine analogue as GSK-3β/Aβ aggregation inhibitor and anti-Alzheimer's agent.

The complex nature of Alzheimer's disease (AD) etiopathology is among the principal hurdles to developing effective anti-Alzheimer agents. Tau pathology and Amyloid-β (Aβ) accumulation are hallmarks and validated therapeutic strategies of AD. GSK-3β is a serine/threonine kinase involved in tau phosphorylation. Its excessive activity also contributes to the production of Aβ plaques, making GSK-3β an attractive AD target. Taking this into account, In this article, we outline the design, synthesis, and biological validation of a focused library of 1,2,3,4-tetrahydropyrimidine based derivatives as inhibitors of GSK-3β, tau phosphorylation, and Aβ accumulation. The inhibitory activity of forty nine synthetic compounds was tested against GSK-3β and other AD-relevant kinases. The kinetic experiments revealed the mode of GSK-3β inhibition by the most potent compound 44. The in- vitro drug metabolism and pharmacokinetic studies were thereafter performed. The anti-aggregation activity of the most potent GSK-3β inhibitor was tested using AD transgenic Caenorhabditis elegans (C. elegans) strain CL2006 for quantification of Aβ plaques and BR5706 C. elegans strain for tau pathology evaluation. We then evaluated the blood-brain barrier permeability and got promising results. Therefore, we present compound 44 as a potential ATP-competitive GSK-3β inhibitor with good metabolism and pharmacokinetic profile, anti-aggregation properties for amyloid beta protein, and reduction in tau-phosphorylation levels. We recommend more investigation into compound 44-based small molecules as possible targets for AD disease-modifying treatments.