Discovery of 2-(cyclopropanecarboxamido)-N-(5-((1-(4-fluorobenzyl)piperidin-4-yl)methoxy)pyridin-3-yl)isonicotinamide as a potent dual AChE/GSK3β inhibitor for the treatment of Alzheimer's disease: Significantly increasing the level of acetylcholine in the brain without affecting that in intestine

Acetylcholinesterase (AChE) inhibitors are currently the first-line drugs approved by the FDA for the treatment of Alzheimer's disease (AD). However, a short effective-window limits their therapeutic benefits. Clinical studies have confirmed that the combination of AChE inhibitors and neuroprotective agents exhibits better anti-AD effects. We have previously reported that the dual AChE/GSK3β (Glycogen synthase kinase 3β) modulators have both neuroprotective effects and cognitive impairment-improvement effects. In this study, we characterized a new backbone of the AChE/GSK3β inhibitor 11c . It was identified as a highly potent AChE inhibitor and was found superior to donepezil, the first-line drug for the treatment of AD. In vivo studies confirmed that 11c significantly inhibited the activity of AChE in the brain but had little effect on the activity of AChE in the intestine. This advantage of 11c was expected to reduce the peripheral side effects caused by donepezil. Furthermore, biomarker studies have shown that 11c also improved the levels of acetylcholine and synaptophysin in the brain and exhibited neuroprotective effects. Preliminary in vivo and in vitro research results underline the exciting potential of compound 11c in the treatment of AD. A series of isonicotinamides have been synthesized as AChE and GSK3 dual inhibitors. Compound with better AChE inhibitory activity than donepezil was identified in vitro and in vivo. Compound 11c significantly inhibited the activity of AChE in the brain but had little effect on the activity of AChE in the intestine. 11c improved the levels of acetylcholine and synaptophysin in the brain and exhibited neuroprotective effects. Demonstrated reversal of scopolamine- or Aβ42-induced learning and memory impairment in ICR mice.