Repurposing of a nucleoside scaffold from adenosine receptor agonists to opioid receptor antagonists

Dilip K. Tosh, Antonella Ciancetta, Philip Mannes, Eugene Warnick, Aaron Janowsky, Amy J. Eshleman, Elizabeth Gizewski, Tarsis F. Brust, Laura M. Bohn, John A. Auchampach, Zhan Guo Gao, Kenneth A. Jacobson

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


While screening off-target effects of rigid (N)methanocarba-adenosine 5′-methylamides as A3 adenosine receptor (AR) agonists, we discovered μM binding hits at the δ-opioid receptor (DOR) and translocator protein (TSPO). In an effort to increase OR and decrease AR affinity by structure activity analysis of this series, antagonist activity at κ-(K)OR appeared in 5′-esters (ethyl 24 and propyl 30), which retained TSPO interaction (μM). 7-Deaza modification of C2-(arylethynyl)-5′-esters but not 4′-truncation enhanced KOR affinity (MRS7299 28 and 29, Ki ≈ 40 nM), revealed μOR and DOR binding, and reduced AR affinity. Molecular docking and dynamics simulations located a putative KOR binding mode consistent with the observed affinities, placing C7 in a hydrophobic region. 3-Deaza modification permitted TSPO but not OR binding, and 1-deaza was permissive to both; ribose-restored analogues were inactive at both. Thus, we have repurposed a known AR nucleoside scaffold for OR antagonism, with a detailed hypothesis for KOR recognition.

Original languageEnglish (US)
Pages (from-to)12658-12678
Number of pages21
JournalACS Omega
Issue number10
StatePublished - Oct 31 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)


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