Structure-Based Discovery Targeting GSK-3α Reveals Potent Nanomolar Selective 4-Phenyl-1H-benzofuro[3,2-b]pyrazolo[4,3-e]pyridine Inhibitor with Promising Glioblastoma and CNS-Active Potential in Cellular Models

Glycogen synthase kinase-3 (GSK-3) is linked with multiple CNS conditions, including glioblastoma (GBM). Compared to the GSK-3β isoform, structure-based inhibitor design targeting GSK-3α is limited. Virtual screening was employed to identify GSK-3α inhibitors with CNS-active potential. Using a GSK-3α homology model, an optimized protocol with three-dimensional (3D)-pharmacophore filtering and Glide-SP docking was used to screen the ZINC20 biogenic subset. From 14 compounds selected for binding assay validation, three novel hit compounds were identified, with 1 (4-phenyl-1H-benzofuro[3,2-b]pyrazolo[4,3-e]pyridine scaffold) exhibiting nanomolar activity against GSK-3α/β (IC50s ∼ 0.26 μM). Selectivity profiling (12 homologous kinases) revealed selectivity for GSK-3α/β and protein kinase A (PKA). Compound 1 was more potent against three GBM cell lines (cell viability IC50s = 3-6 μM at 72 h) compared to benchmark GSK-3 inhibitor, 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), and nontoxic to human astrocytes. It demonstrated CNS-active potential in an all-human in vitro blood-brain barrier GBM model, good in vitro metabolic stability, excellent predicted oral bioavailability and represents a promising lead compound for development.