Multi-target-directed chromone-carboxamide hybrids: Potent AChE/MAO-B inhibitors with anti-Aβ/Tau and neuroprotective...

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder involving cholinergic dysfunction, amyloid-β (Aβ) and Tau aggregation, oxidative stress, and neuroinflammation. To address the limited efficacy of single-target therapies, a series of chromone-2-carboxamide derivatives (E1-E29) were rationally designed, synthesized, and evaluated as potential multi-target-directed ligands (MTDLs). The target compounds exhibited moderate to potent inhibitory activity against acetylcholinesterase (AChE), with several derivatives (E3, E5, E12) showing submicromolar IC₅₀ values comparable to donepezil and pronounced selectivity over butyrylcholinesterase. Selected compounds also demonstrated preferential inhibition of monoamine oxidase-B (MAO-B), with E7 and E8 approaching the activity of selegiline. Mechanistic studies revealed that E3 and E12 acted as reversible noncompetitive AChE inhibitors. Both compounds effectively inhibited Aβ₄₀/₄₂ and Tau fibrillization, promoted Aβ fibril disaggregation, and suppressed intracellular amyloid accumulation, accompanied by significant antioxidant and neuroprotective effects in SH-SY5Y cells. In vivo, E12 markedly improved scopolamine-induced memory deficits in mice without observable systemic toxicity. Molecular docking and dynamics simulations supported stable binding of E3 and E12 to AChE, Aβ, and Tau targets via π-π and H-π interactions, accompanied by disruption of hydrophobic networks. Collectively, these findings identify chromone-2-carboxamide hybrids, particularly E3 and E12, as promising scaffolds for the development of multi-target anti-AD drug candidates.