Biological evaluation and energetic analyses of novel GSK-3β inhibitors

Glycogen synthase kinase-3 beta (GSK-3β) is involved in multiple signaling pathways. Consistent with its critical roles in normal cells, abnormalities in GSK-3β activity have been implicated in diabetes, heart disease, Parkinson disease, and Alzheimer's disease. In this study, a series of new scaffolds of small molecule inhibitors of GSK-3β were identified by virtual screening and bioassay. Candidates that adhere to drug-like criteria from a virtual library of compounds were tested using computational docking studies. Twenty selected compounds were tested, which led to the discovery of two hits. Compound 14 (IC₅₀  = 8.48 µM) and compound 19 (IC₅₀  = 2.19 µM) were identified with high affinity. Molecular dynamics (MD) simulations, in conjunction with molecular mechanics/Poisson-Boltzmann surface area binding free-energy analysis, were employed to gain insight into the binding modes and energetics of GSK-3β inhibitors. The detailed analysis of molecular dynamics results shows that Ile62, Val70, Tyr134, and Leu188 in GSK-3β are key residues responsible to the binding of compound 14 and compound 19. Importantly, our results also validated this combined virtual screening and biophysical technique approach to discovery kinase inhibitors, which may be applied for future inhibitor discovery work for GSK-3β.