The synthesis, biochemical evaluation, ADMET, toxicity and molecular modeling of novel multi-target-directed
Donepezil +
Propargylamine +
8-Hydroxyquinoline (DPH) hybrids 1-7 for the potential prevention and treatment of
Alzheimer's disease is described. The most interesting derivative was racemic α-aminotrile4-(1-benzylpiperidin-4-yl)-2-(((8-hydroxyquinolin-5-yl)methyl)(prop-2-yn-1-yl)amino) butanenitrile (DPH6) [
MAO A (IC50 = 6.2 ± 0.7 μM;
MAO B (IC50 = 10.2 ± 0.9 μM); AChE (IC50 = 1.8 ± 0.1 μM); BuChE (IC50 = 1.6 ± 0.25 μM)], an irreversible
MAO A/B inhibitor and mixed-type AChE inhibitor with
metal-chelating properties. According to docking studies, both DPH6 enantiomers interact simultaneously with the catalytic and peripheral site of EeAChE through a linker of appropriate length, supporting the observed mixed-type AChE inhibition. Both enantiomers exhibited a relatively similar position of both hydroxyquinoline and benzyl moieties with the rest of the molecule easily accommodated in the relatively large cavity of
MAO A. For
MAO B, the
quinoline system was hosted at the cavity entrance whereas for
MAO A this system occupied the substrate cavity. In this disposition the
quinoline moiety interacted directly with the
FAD aromatic ring. Very similar binding affinity values were also observed for both enantiomers with ChE and
MAO enzymes. DPH derivatives exhibited moderate to good ADMET properties and brain penetration capacity for CNS activity. DPH6 was less toxic than
donepezil at high concentrations; while at low concentrations both displayed a similar cell viability profile. Finally, in a passive avoidance task, the antiamnesic effect of DPH6 was tested on mice with experimentally induced
amnesia. DPH6 was capable to significantly decrease
scopolamine-induced learning deficits in healthy adult mice.