Synthesis and Biological Evaluation of 3-Benzisoxazolyl-4-indolylmaleimides as Potent, Selective Inhibitors of Glycogen Synthase Kinase-3β

A series of novel 3-benzisoxazolyl-4-indolyl-maleimides were synthesized and evaluated for their GSK-3β inhibitory activity. Most compounds exhibited high inhibitory potency towards GSK-3β. Among them, compound 7j with an IC(50) value of 0.73 nM was the most promising GSK-3β inhibitor. Preliminary structure-activity relationships were examined and showed that different substituents on the indole ring and N(1)-position of the indole ring had varying degrees of influence on the GSK-3β inhibitory potency. Compounds 7c, 7f, 7j–l and 7o–q could obviously reduce Aβ-induced Tau hyperphosphorylation by inhibiting GSK-3β in a cell-based functional assay.