Design, synthesis and preliminary biological evaluation of rivastigmine-INDY hybrids as multitarget ligands against Alzheimer's disease by targeting butyrylcholinesterase and DYRK1A/CLK1 kinases.

Based on a multitarget approach implementing rivastigmine-INDY hybrids 1, we identified a set of pseudo-irreversible carbamate-type inhibitors of eq BuChE that, after carbamate transfer at the active site serine residue, released the corresponding INDY analogues 2 endowed with h DYRK1A/ h CLK1 kinases inhibitory properties. A SAR study and molecular docking investigation of both series of compounds 1 and 2 revealed that appropriate structural modifications at the carbamate moiety and at the N -appendage of the benzothiazole core led to potent and selective eq BuChE inhibitors with IC 50 up to 27 nM and potent h DYRK1A and h CLK1 inhibitors with IC 50 up to 106 nM and 17 nM respectively. Pleasingly, identification of the matched pair of compounds 1b/2b with a good balance between inhibition of eq BuChE and h DYRK1A/ h CLK1 kinases (IC 50 = 68 nM and IC 50 = 529/54 nM, respectively) further validated our multitarget approach based on a sequential mechanism of action. In addition, target compound 1b exhibited a suitable ADMET profile, including good brain permeability and high stability in PBS, encouraging further biological investigation as a drug candidate.