Pharmacophore Modeling, Quantitative Structure–Activity Relationship Analysis, and in Silico Screening Reveal Potent Glycogen Synthase Kinase-3β Inhibitory Activities for Cimetidine, Hydroxychloroquine, and Gemifloxacin

The pharmacophoric space of glycogen synthase kinase-3� (GSK-3� ) was explored using two diverse sets of inhibitors. Subsequently, genetic algorithm and multiple linear regression analysis were employed to select optimal combination of pharmacophores and physicochemical descriptors that access self-consistent and predictive quantitative structure–activity relationship (QSAR) against 132 training compounds (r 2 123 ) 0.663, F ) 24.6, r 2 LOO ) 0.592, r 2 PRESS against 29 external test inhibitors ) 0.695). Two orthogonal pharmacophores emerged in the QSAR, suggesting the existence of at least two distinct binding modes accessible to ligands within GSK-3� binding pocket. The validity of the QSAR equation and the associated pharmacophores was established by the identification of three nanomolar GSK-3� inhibitors retrieved from our in-house-built structural database of established drugs, namely, hydroxychloroquine, cimetidine, and gemifloxacin. Docking studies supported the binding modes suggested by the pharmacophore/QSAR analysis. In addition to being excellent leads for subsequent optimization, the anti-GSK-3� activities of these drugs should have significant clinical implications.