Structural Requirements for CNS Active Opioid Glycopeptides

J Med Chem. 2015 Aug 13;58(15):5728-41. doi: 10.1021/acs.jmedchem.5b00014. Epub 2015 Jul 23.

Abstract

Glycopeptides related to β-endorphin penetrate the blood-brain barrier (BBB) of mice to produce antinociception. Two series of glycopeptides were assessed for opioid receptor binding affinity. Attempts to alter the mu-selectivity of [D-Ala(2),N-MePhe(4),Gly-ol(5)]enkephalin (DAMGO)-related glycopeptides by altering the charged residues of the amphipathic helical address were unsuccessful. A series of pan-agonists was evaluated for antinociceptive activity (55 °C tail flick) in mice. A flexible linker was required to maintain antinociceptive activity. Circular dichroism (CD) in H2O, trifluoroethanol (TFE), and SDS micelles confirmed the importance of the amphipathic helices (11s → 11sG → 11) for antinociception. The glycosylated analogues showed only nascent helices and random coil conformations in H2O. Chemical shift indices (CSI) and nuclear Overhauser effects (NOE) with 600 MHz NMR and CD confirmed helical structures in micelles, which were rationalized by molecular dynamics calculations. Antinociceptive studies with mice confirm that these glycosylated endorphin analogues are potential drug candidates that penetrate the BBB to produce potent central effects.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Central Nervous System / drug effects*
  • Circular Dichroism
  • Glycopeptides / chemistry
  • Glycopeptides / pharmacology*
  • Magnetic Resonance Spectroscopy
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Opioid Peptides / chemistry
  • Opioid Peptides / pharmacology*
  • Protein Conformation
  • Receptors, Opioid, mu / drug effects

Substances

  • Glycopeptides
  • Opioid Peptides
  • Receptors, Opioid, mu