3-Alkyl- and 3-amido-isothiazoloquinolin-4-ones as ligands for the benzodiazepine site of GABAA receptors

Research output: Contribution to journalJournal articleResearchpeer-review

Jakob Nilsson, Elsebet Østergaard Nielsen, Tommy Liljefors, Mogens Peter Cherly Nielsen, Olov Sterner

Based on a pharmacophore model of the benzodiazepine binding site of the GABA(A) receptors, developed with synthetic flavones and potent 3-carbonylquinolin-4-ones, 3-alkyl- and 3-amido-6-methylisothiazoloquinolin-4-ones were designed, prepared and assayed. The suggestion that the interaction between the hydrogen bond donor site H1 with the 3-carbonyl oxygen in 3-carbonylquinolin-4-ones can be replaced by an interaction between H1 and N-2 in the isothiazoloquinolin-4-ones, was confirmed. As with the 3-carbonylquinolin-4-ones, the length of the chain in position 3 is critical for an efficient interaction with the lipophilic pockets of the pharmacophore model. The most potent 3-alkyl derivative, 3-pentyl-6-methylisothiazoloquinolin-4-one, has an affinity (K(i) value) for the benzodiazepine binding site of the GABA(A) receptors of 13nM. However, by replacing the 3-pentyl with a 3-butyramido group an even more potent compound was obtained, with a K(i) value of 2.8nM, indicating that the amide function facilitates additional interactions with the binding site.
Original languageEnglish
JournalBioorganic Chemistry
Volume40
Pages (from-to)125-130
ISSN0045-2068
DOIs
Publication statusPublished - Feb 2012

Bibliographical note

Keywords: 3-alkyl-6-methylisothiazolo[5,4-b]quinolin-4(9H)-ones; 3-amido-6-methylisothiazolo[5,4-b]quinolin-4(9H)-ones; benzodiazepine binding site; GABA(A) receptors; pharmacophore model

ID: 35379099