Novel Analogues of (R)-5-(Methylamino)-5,6-dihydro-4H-imidazo[4,5,1-ij]quinolin-2(1H)-one (Sumanirole) Provide Clues to Dopamine D2/D3 Receptor Agonist Selectivity

Mu Fa Zou, Thomas M. Keck, Vivek Kumar, Prashant Donthamsetti, Mayako Michino, Caitlin Burzynski, Catherine Schweppe, Alessandro Bonifazi, R. Benjamin Free, David R. Sibley, Aaron Janowsky, Lei Shi, Jonathan A. Javitch, Amy Hauck Newman

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30 Scopus citations


Novel 1-, 5-, and 8-substituted analogues of sumanirole (1), a dopamine D2/D3 receptor (D2R/D3R) agonist, were synthesized. Binding affinities at both D2R and D3R were higher when determined in competition with the agonist radioligand [3H]7-hydroxy-N,N-dipropyl-2-aminotetralin (7-OH-DPAT) than with the antagonist radioligand [3H]N-methylspiperone. Although 1 was confirmed as a D2R-preferential agonist, its selectivity in binding and functional studies was lower than previously reported. All analogues were determined to be D2R/D3R agonists in both GoBRET and mitogenesis functional assays. Loss of efficacy was detected for the N-1-substituted analogues at D3R. In contrast, the N-5-alkyl-substituted analogues, and notably the n-butyl-arylamides (22b and 22c), all showed improved affinity at D2R over 1 with neither a loss of efficacy nor an increase in selectivity. Computational modeling provided a structural basis for the D2R selectivity of 1, illustrating how subtle differences in the highly homologous orthosteric binding site (OBS) differentially affect D2R/D3R affinity and functional efficacy.

Original languageEnglish (US)
Pages (from-to)2973-2988
Number of pages16
JournalJournal of Medicinal Chemistry
Issue number7
StatePublished - Apr 28 2016

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Drug Discovery


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