Research of new active substances for the treatment of Alzheimer's disease (AD), a leading cause of dementia, is gaining an importance. Existing symptomatic treatments, mostly consisting of acetylcholineesterase (AChE) inhibitors, have a short-term effect and are particularly suitable for treatment of early stages of the disease. With progression of AD, there is an increase in activity and concentration of the butyrylcholineesterase (BChE), which is therefore a promising target for the design of new active substances for symptomatic treatment in the later stages of AD.
In this master's thesis we have focused on the research of novel agents that are selective for BChE and consequently demonstrate the possibility of treatment in the later stages of the disease. For that purpose, we synthesized various target amides, which are selective inhibitors of the BChE. These were synthesized on the basis of a proposed library of target amides, which was generated using lead compound and computational virtual screening.
The amino acid L-tryptophan was used as the starting molecule, to which various long alkyl groups were attached to the amine moiety. By attachment of selected amines, an amide bond was formed using the carboxyl group. The prepared compounds were fully characterized and their in vitro activity was evaluated on hBChE and hAChE enzymes using the Ellman method.
We synthesized 11 novel BChE-selective tryptophan α-aminoamides with a mean inhibitory concentrations in the nanomolar range. The compounds with the ethyl spacer between the simple cycloalkyl ring and the amide group on the carboxyl moiety, and the n-butyl handle on the amine moiety of L-tryptophan, showed the best inhibitory activity. In the series of new inhibitors, the strongest inhibitor was compound 11 with IC50 value of 23.1 nM.
Due to the simple synthesis and promising results of the bioassay, we can confirm that the tryptophan-based compounds provide a suitable basis for further optimization as lead compounds in the design of new BChE inhibitors.
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