Synthesis and Structure-Affinity Relationships of Spirocyclic Benzopyrans with Exocyclic Amino Moiety

J Med Chem. 2019 Apr 25;62(8):4204-4217. doi: 10.1021/acs.jmedchem.9b00449. Epub 2019 Apr 12.

Abstract

σ1 and/or σ2 receptors play a crucial role in pathological conditions such as pain, neurodegenerative disorders, and cancer. A set of spirocyclic cyclohexanes with diverse O-heterocycles and amino moieties (general structure III) was prepared and pharmacologically evaluated. In structure-activity relationships studies, the σ1 receptor affinity and σ12 selectivity were correlated with the stereochemistry, the kind and substitution pattern of the O-heterocycle, and the substituents at the exocyclic amino moiety. cis-configured 2-benzopyran cis-11b bearing a methoxy group and a tertiary cyclohexylmethylamino moiety showed the highest σ1 affinity ( Ki = 1.9 nM) of this series of compounds. In a Ca2+ influx assay, cis-11b behaved as a σ1 antagonist. cis-11b reveals high selectivity over σ2 and opioid receptors. The interactions of the novel σ1 ligands were analyzed on the molecular level using the recently reported X-ray crystal structure of the σ1 receptor protein. The protonated amino moiety forms a persistent salt bridge with E172. The spiro[benzopyran-1,1'-cyclohexane] scaffold and the cyclohexylmethyl moiety occupy two hydrophobic pockets. Exchange of the N-cyclohexylmethyl moiety by a benzyl group led unexpectedly to potent and selective μ-opioid receptor ligands.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzopyrans / chemical synthesis
  • Benzopyrans / chemistry*
  • Benzopyrans / metabolism
  • Binding Sites
  • Crystallography, X-Ray
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Ligands
  • Molecular Dynamics Simulation
  • Protein Structure, Tertiary
  • Receptors, Opioid, mu / chemistry
  • Receptors, Opioid, mu / metabolism
  • Receptors, sigma / chemistry
  • Receptors, sigma / metabolism
  • Sigma-1 Receptor
  • Spiro Compounds / chemistry*
  • Structure-Activity Relationship

Substances

  • Benzopyrans
  • Ligands
  • Receptors, Opioid, mu
  • Receptors, sigma
  • Spiro Compounds
  • sigma-2 receptor