Structure-activity relationships of bifunctional peptides based on overlapping pharmacophores at opioid and cholecystokinin receptors

Richard S. Agnes, Yeon Sun Lee, Peg Davis, Shou Wu Ma, Hamid Badghisi, Frank Porreca, Josephine Lai, Victor J. Hruby

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Cholecystokinin (CCK) has been identified as a pronociceptive endogenous peptide which also possesses antiopioid actions. CCK may be upregulated in conditions of chronic pain or during sustained morphine administration resulting in attenuation of opioid-mediated pain relief. These complex interactions between opioids and endogenous CCK receptor systems have suggested the need for a new paradigm in drug design for some states of chronic pain. In these circumstances the rational design of potential drugs for the treatment of these conditions must be based on one ligand for multiple targets. We have designed a single peptide which can interact with δ and μ opioid receptors as agonists and with CCK receptors as antagonists. The ligands were designed based on a model of overlapping pharmacophores of opioid and CCK peptide ligands, which incorporates opioid pharmacophores at the N-terminal and CCK tetrapeptide pharmacophores at the C-terminal of the designed ligands. We measured binding and activities of our bifunctional peptides at opioid and CCK receptors. Compound 11 (Tyr-D-Ala-Gly-D-Trp-NMeNle-Asp-Phe-NH2) demonstrated opioid agonist properties at δ and μ receptors (IC50 = 63 ± 27 nM and 150 ± 65 nM, respectively in MVD and GPI tissue assays) and high binding affinity at CCK-1 and CCK-2 receptors (Ki = 320 and 1.5 nM, respectively). Compound 9 (Tyr-D-Nle-Gly-Trp-Nle-Asp-Phe-NH 2) displayed potent agonist activity at δ and μ receptors (IC50 = 23 ± 10 nM and 210 ± 52 nM, respectively in MVD and GPI tissue assays), with a balanced binding affinity for CCK-1 and CCK-2 receptors (Ki = 9.6 and 15 nM, respectively). These results provide evidence supporting the concept that opioid and CCK receptors have overlapping pharmacophores required for binding affinity and biological activity and that designing overlapping pharmacophores of two peptides into a single peptide is a valid drug design approach.

Original languageEnglish (US)
Pages (from-to)2868-2875
Number of pages8
JournalJournal of Medicinal Chemistry
Issue number10
StatePublished - May 18 2006

ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery


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