The selection of approved drugs for the (symptomatic) treatment of Alzheimer’s disease and their effectiveness are relatively limited, so the need for developing new agents for the therapy of this neurodegenerative disease is of great significance. Molecules acting on more than one target involved in the complex pathophysiology of Alzheimer’s disease are of great interest in this area of research. Two of the targets of the potential new active substances for the (symptomatic) treatment of Alzheimer’s disease are the enzymes butyrylcholinesterase (BChE) and monoamine oxidase B (MAO-B) – expression of both is increased in the brains of Alzheimer’s patients. Inhibition of BChE slows the breakdown of the neurotransmitter acetylcholine (ACh) and relieves the cognitive symptoms of Alzheimer’s disease without the cholinergic side effects typical of acetylcholine esterase (AChE) inhibitors. Inhibition of MAO-B reduces the oxidative stress, which fuels neurodegenerative processes.
30 new N-alkylpyrrolidine carbamates were prepared and their inhibitory activity on BChE and MAO-B was evaluated with enzymatic tests in vitro. All the compounds affecting the cholinesterases showed good selectivity towards BChE over AChE. The most effective BChE inhibitors of the series [45 (IC50 = 22,24 nM), 46 (IC50 = 34,43 nM), 47 (IC50 = 27,16 nM) and 48 (IC50 = 21,02 nM)] inhibited this enzyme in a time dependent manner which suggests the covalent mode of action. For compound 45, this was confirmed with enzyme kinetic measurements. Covalent binding of the most potent MAO-B inhibitor, compound 36 (IC50 = 0,36 μM), was expected based on the presence of the N-propargil amino group. Among the compounds that showed inhibitory activity against both target enzymes, compound 38 [IC50(BChE) = 34,69 μM; IC50(MAO-B) = 1,53 μM)] was the most promising.
With this master thesis, we have demonstrated that N-alkylpyrrolidine carbamates are very interesting new BChE and MAO-B inhibitors in the nanomolar range with great potential to be developed into safer and more effective agents for alleviating the symptoms and treatment of Alzheimer’s disease.
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