Acetylcholinesterase Inhibition of Diversely Functionalized Quinolinones for Alzheimer's Disease Therapy

In this communication, wereport the synthesis and cholinesterase (ChE)/monoamine oxidase (MAO) inhibition of 19 quinolinones (QN1-19) and 13 dihydroquinolinones (DQN1-13) designed as potential multitarget small molecules (MSM) for Alzheimer¿s disease therapy. Contrary to our expectations, none of them showed significant human recombinant MAO inhibition, but compounds QN8, QN9, and DQN7 displayed promising human recombinant acetylcholinesterase (hrAChE) and butyrylcholinesterase (hrBuChE) inhibition. In particular, molecule QN8 was found to be a potent and quite selective non-competitive inhibitor of hrAChE (IC50 = 0.29 M), with Ki value in nanomolar range (79 nM). Pertinent docking analysis confirmed this result, suggesting that this ligand is an interesting hit for further investigation.R.A., M.S., P.B., and K.M. were supported by European Regional Development Fund/European Social Fund (ERDF/ESF, project PharmaBrain, no. CZ.02.1.01/0.0/0.0/16_025/0007444), University of Hradec Kralove (no. SV2113-2019, VT2019-2021), and EU COST action CA15135 MuTaLig. J.M.C. thanks Ministerio de Economía (MINECO, SAF2015-65586-R) and Universidad Camilo José Cela (UCJC, grants UCJC 2020-03, and UCJC 2020-33) for support

Discovery of (1<i>S</i>,2<i>R</i>,3<i>S</i>,4<i>S</i>,5<i>R</i>,6<i>R</i>)‑2-Amino-3-[(3,4-difluorophenyl)sulfanylmethyl]-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylic Acid Hydrochloride (LY3020371·HCl): A Potent, Metabotropic Glutamate 2/3 Receptor Antagonist with Antidepressant-Like Activity

As part of our ongoing efforts to identify novel ligands for the metabotropic glutamate 2 and 3 (mGlu_2/3) receptors, we have incorporated substitution at the C3 and C4 positions of the (1<i>S</i>,2<i>R</i>,5<i>R</i>,6<i>R</i>)-2-amino-bicyclo­[3.1.0]­hexane-2,6-dicarboxylic acid scaffold to generate mGlu_2/3 antagonists. Exploration of this structure–activity relationship (SAR) led to the identification of (1<i>S</i>,2<i>R</i>,3<i>S</i>,4<i>S</i>,5<i>R</i>,6<i>R</i>)-2-amino-3-[(3,4-difluorophenyl)­sulfanylmethyl]-4-hydroxy-bicyclo­[3.1.0]­hexane-2,6-dicarboxylic acid hydrochloride (LY3020371·HCl, <b>19f</b>), a potent, selective, and maximally efficacious mGlu_2/3 antagonist. Further characterization of compound <b>19f</b> binding to the human metabotropic 2 glutamate (hmGlu₂) site was established by cocrystallization of this molecule with the amino terminal domain (ATD) of the hmGlu₂ receptor protein. The resulting cocrystal structure revealed the specific ligand–protein interactions, which likely explain the high affinity of <b>19f</b> for this site and support its functional mGlu₂ antagonist pharmacology. Further characterization of <b>19f</b> in vivo demonstrated an antidepressant-like signature in the mouse forced-swim test (mFST) assay when brain levels of this compound exceeded the cellular mGlu₂ IC₅₀ value