79985-34-5Relevant articles and documents
Design and synthesis of highly potent and selective cyclic dynorphin A analogs. 2. New analogs
Kawasaki,Knapp,Kramer,Walton,Wire,Hashimoto,Yamamura,Porreca,Burks,Hruby
, p. 750 - 757 (1993)
We have designed and synthesized several cyclic disulfide-containing peptide analogs of dynorphin A (Dyn A) which are conformationally constrained in the putative 'address' segment of the opioid ligand. Several of these Dyn A analogs exhibit unexpected apparent selectivities for the κ and μ opioid receptors(s) of the central vs peripheral nervous systems. Thus, incorporation of conformational constraint in the putative 'address' segment of Dyn A analogs has resulted in the κ/μ opioid receptor ligands [L- Pen5,Cys11]Dyn A1-11-NH2 (4), [Cys5,Cys10]Dyn A1-11-NH2 (5), [Cys5,Cys9]Dyn A1-11-NH2 (6), and [Cys4,Cys9,Arg10]Dyn A1-11- NH2 (7). All of these analogs possess high κ and μ opioid receptor affinities for the central receptor (guinea pig brain), but effect only weak potency at peripheral κ and μ opioid receptors (GPI). In fact cyclic dynorphin A analog 4 shows >19 000-fold differences between central κ opioid affinity and potency in the guinea pig ileum (GPI). Additionally analog 4 is not an antagonist in the GPI, suggesting possible receptor differences between these sites. Substitution of Tyr1 by Phe1 in the cyclic 1-11 series gave the analog [Phe1,Cys5,Cys11]Dyn A1-11-NH2 (1) that was surprisingly potent in the guinea pig brain binding assay (IC50 = 15.1 nM) at the κ receptor, but was inactive in the GPI and mouse vas deferens bioassays. D-Ala2 and Tic4 analogs of 1 had lower affinity at brain κ receptors and had very weak potencies in the GPI and MVD bioassays. On the other hand, [Cys6,Cys10]Dyn A1-11-NH2 (8), [Cys8,D-Cys13]Dyn A1- 13-NH2 (9), [D-Cys8,D-Cys12]Dyn A1-13-NH2 (10), and [D- Pro10,Cys5,Cys13]Dyn A1-13-NH2 (11) were surprisingly potent in the GPI bioassay, though considerable apparent selectivity for central receptors is still retained. The apparent lack of correlation between the pharmacological profiles observed in smooth muscle and in the brain binding assays, particularly with 1 and 4, may suggest the existence of different subtypes of the κ and μ opioid receptors in the brain and peripheral systems.
Synthesis and Biological Activities of Dynorphin A Analogues with Opioid Antagonist Properties
Gairin, Jean E.,Mazarguil, Honore,Alvinerie, Paul,Saint-Pierre, Serge,Meunier, Jean-Claude,Cros, Jean
, p. 1913 - 1917 (2007/10/02)
Dynorphin A, which displays a wide variety of physiological effects, binds to opioid receptors preferentially at the κ receptor type. κ-selective antagonists would be very useful as pharmacological and biochemical probes to study and better understand the action of dynorphin A at its preferred receptor. However, the development of such molecules has been elusive, and very few are known at this time. Taking these features into account, we have synthesized by the solid-phase procedure several analogues of dynorphin A containing various D-amino acid substitutions. The binding properties of the peptides have been examined at three main opioid binding sites (μ, δ, and κ) and their κ selectivity determined. Their biological activities have been tested in three specific pharmacological assays for agonist and/or antagonist properties. Introduction of D-Trp substitution leads to analogues, in particular 2,8,D-Pro10>-, 5,8,D-Pro10>-, and 2,4,8,D-Pro10>dynorphin(1-11), showing antagonist properties in the isolated rabbit vas deferens preparation, a κ specific bioassay. The antagonism against dynorphin A is weak, as indicated by the observed Ke values (433, 199, and 293 nM, respectively), and not very selective (κ vs. μ). Such peptide analogues derived from the endogenous ligand and endowed with antagonist properties are the first ones reported to date and could open a promissing way in designing more potent and selective κ opioid antagonists.
