1,2,3,4-Tetrahydrobenzo[h][1,6]naphthyridines as a new family of potent peripheral-to-midgorge-site inhibitors of acetylcholinesterase: Synthesis, pharmacological evaluation and mechanistic studies

Ornella Di Pietro, Elisabet Viayna, Esther Vicente-García, Manuela Bartolini, Rosario Ramón, Jordi Juárez-Jiménez, M. Victòria Clos, Belén Pérez, Vincenza Andrisano, F. Javier Luque, Rodolfo Lavilla, Diego Muñoz-Torrero

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28 Citations (Scopus)

Abstract

A series of 1,2,3,4-tetrahydrobenzo[h][1,6]naphthyridines differently substituted at positions 1, 5, and 9 have been designed from the pyrano[3,2-c]quinoline derivative 1, a weak inhibitor of acetylcholinesterase (AChE) with predicted ability to bind to the AChE peripheral anionic site (PAS), at the entrance of the catalytic gorge. Fourteen novel benzonaphthyridines have been synthesized through synthetic sequences involving as the key step a multicomponent Povarov reaction between an aldehyde, an aniline and an enamine or an enamide as the activated alkene. The novel compounds have been tested against Electrophorus electricus AChE (EeAChE), human recombinant AChE (hAChE), and human serum butyrylcholinesterase (hBChE), and their brain penetration has been assessed using the PAMPA-BBB assay. Also, the mechanism of AChE inhibition of the most potent compounds has been thoroughly studied by kinetic studies, a propidium displacement assay, and molecular modelling. We have found that a seemingly small structural change such as a double O → NH bioisosteric replacement from the hit 1 to 16a results in a dramatic increase of EeAChE and hAChE inhibitory activities (>217- and >154-fold, respectively), and in a notable increase in hBChE inhibitory activity (>11-fold), as well. An optimized binding at the PAS besides additional interactions with AChE midgorge residues seem to account for the high hAChE inhibitory potency of 16a (IC 50 = 65 nM), which emerges as an interesting anti-Alzheimer lead compound with potent dual AChE and BChE inhibitory activities. © 2013 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)141-152
JournalEuropean Journal of Medicinal Chemistry
Volume73
DOIs
Publication statusPublished - 12 Feb 2014

Keywords

  • AChE PAS binding
  • AChE midgorge binding
  • Benzo[h][1,6]naphthyridines
  • Dual inhibitors
  • Povarov reaction

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