A series of novel isoflavone analogs were designed, synthesized, and evaluated as multitarget-directed ligands for the treatment of Alzheimer's disease. In vitro evaluations revealed that some ligands had multifunctional profiles, including potent blockage of histamine 3 receptor (H3R), excellent inhibition of acetylcholinesterase (AChE), neuroprotective effects and anti-neuroinflammatory properties. Among these derivatives, compound 9b exhibited the highest ability to block H3R (IC50 = 0.27 μM) and good inhibitory activity against AChE (IC50 = 0.08 μM). Additionally, compound 9b showed obvious neuroprotective effect on SH-SY5Y by preventing copper-induced neuronal damage and potent anti-neuroinflammatory activity by inhibiting the production of inflammatory factors on BV-2 cells. A molecular modeling study revealed that 9b acts as a mixed-type inhibitor that interacts simultaneously with H3R and AChE. Moreover, in vivo data revealed that compound 9b did not cause acute toxicity in mice at doses up to 1000 mg/kg, and had desirable pharmacokinetic properties, as well as a good blood-brain barrier (BBB) permeability (log BB = 1.24 ± 0.07). Further studies demonstrated that chronic oral treatment with 9b significantly improved cognitive dysfunction in scopolamine-induced AD mice in the step-down passive avoidance test. Taken together, the present study showed that compound 9b is a promising multifunctional drug candidate for the treatment of Alzheimer's disease.
Keywords: Acetylcholinesterase; Alzheimer's disease; Histamine 3 receptor; Isoflavone analogs; Multifunctional agents; Neuroprotection.
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