Dual inhibitory potential of N-methylcytisine against GSK-3β and AChE: implications for Alzheimer's disease treatment.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss and irreversible cognitive decline. Glycogen synthase kinase 3β (GSK-3β) is significant in tau hyperphosphorylation and neurodegeneration. The cholinergic hypothesis of AD links cognitive impairment to reduced synaptic acetylcholine (ACh). Increased acetylcholinesterase (AChE) activity exacerbates this issue. To search for a potential dual GSK-3β/AChE inhibitor, we focused on N-methylcytisine. This natural cytisine-derived alkaloid has not been studied for its various biological effects on the prevention of AD. The in vitro results indicated that N-methylcytisine displayed promising activity against GSK-3β and AChE with IC50 values of 11 and 22.7 µM, respectively. GSK-3β kinetic study according to the varying substrate or ATP concentrations at different N-methylcytisine levels revealed mixed-type inhibition. The results of the integrated in silico workflow indicate that N-methylcytisine exhibited favorable binding to AChE (docking score -9.6 kcal/mol; MM-GBSA -70.2 kcal/mol), comparable to the reference inhibitor galantamine (-10.8 kcal/mol; -70.6 kcal/mol). In contrast, its interaction with GSK-3β was more moderate (-5.3 kcal/mol; -50.3 kcal/mol) relative to staurosporine (-8.5 kcal/mol; -82.6 kcal/mol), consistent with its smaller scaffold. Overall, the results support a flexible, mixed-type interaction profile and highlight N-methylcytisine as a promising dual-acting candidate for Alzheimer's disease.