title: Evolution of the Bifunctional Lead μ Agonist / δ Antagonist Containing the Dmt-Tic Opioid Pharmacophore.
abstract: Based on a renewed importance recently attributed to bi- or multifunctional opioids, we report the synthesis and pharmacological evaluation of some analogues derived from our lead μ agonist / δ antagonist, H-Dmt-Tic-Gly-NH-Bzl. Our previous studies focused on the importance of the C-teminal benzyl function in the induction of such bifunctional activity. The introduction of some substituents in the para position of the phenyl ring (-Cl, -CH(3), partially -NO(2), inactive -NH(2)) was found to give a more potent μ agonist / antagonist effect associated with a relatively unmodified δ antagonist activity (pA(2) = 8.28-9.02). Increasing the steric hindrance of the benzyl group (using diphenylmethyl and tetrahydroisoquinoline functionalities) substantially maintained the μ agonist and δ antagonist activities of the lead compound. Finally and quite unexpectedly D-Tic2, considered as a wrong opioid message now; inserted into the reference compound in lieu of L-Tic, provided a μ agonist / δ agonist better than our reference ligand (H-Dmt-Tic-Gly-NH-Ph) and was endowed with the same pharmacological profile.
authors.affiliation: Department of Toxicology, University of Cagliari, I-09124, Cagliari, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Balboni
authors.forename: Severo
authors.initials: S
authors.lastname: Salvadori
authors.forename: Claudio
authors.initials: C
authors.lastname: Trapella
authors.forename: Brian I
authors.initials: BI
authors.lastname: Knapp
authors.forename: Jean M
authors.initials: JM
authors.lastname: Bidlack
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Lazarus
authors.forename: Xuemei
authors.initials: X
authors.lastname: Peng
authors.forename: John L
authors.initials: JL
authors.lastname: Neumeyer