title: Synthesis, biological evaluation and structural analysis of novel peripherally active morphiceptin analogs.
abstract: Morphiceptin (Tyr-Pro-Phe-Pro-NH2), a tetrapeptide amide, is a selective ligand of the μ-opioid receptor (MOR). This study reports the synthesis and biological evaluation of a series of novel morphiceptin analogs modified in positions 2 or/and 4 by introduction of 4,4-difluoroproline (F2Pro) in l or d configuration. Depending on the fluorinated amino acid configuration and its position in the sequence, new analogs behaved as selective full MOR agonists showing high, moderate, or relatively low potency. The most potent analog, Tyr-F2Pro-Phe-D-F2Pro-NH2, was also able to activate the κ-opioid receptor (KOR), although with low potency. Docking studies and the comparison of results with the high resolution crystallographic structure of a MOR-agonist complex revealed possible structure-activity relationships of this compound family.
authors.affiliation: Department of Biomolecular Chemistry, Faculty of Medicine, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Adamska
authors.affiliation: Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Kluczyk
authors.affiliation: Department of Medical Sciences, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy.
authors.forename: Maria Camilla
authors.initials: MC
authors.lastname: Cerlesi
authors.affiliation: Department of Medical Sciences, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy.
authors.forename: Girolamo
authors.initials: G
authors.lastname: Calo
authors.affiliation: Department of Biomolecular Chemistry, Faculty of Medicine, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Janecka
authors.affiliation: Institute of Biochemistry, Biological Research Centre of Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, Hungary. Electronic address: borics.attila@brc.mta.hu.
authors.forename: Attila
authors.initials: A
authors.lastname: Borics
mesh_terms: D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D017473:Receptors, Opioid, kappa / Q000819:agonists*; D017450:Receptors, Opioid, mu / Q000819:agonists*; D013329:Structure-Activity Relationship
chemical_list: D004723:Endorphins; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; C028889:morphiceptin
keywords: Binding studies; Docking; Gastrointestinal transit; Hot-plate test; Molecular dynamics; Opioid receptors; Solid-phase peptide synthesis