CB-64D and CB-184: ligands with high sigma 2 receptor affinity and subtype selectivity

Area of Science:

• Medicinal Chemistry
• Neuropharmacology
• Receptor Binding Assays

Background:

• Sigma receptors are implicated in various neurological processes.
• Developing subtype-selective ligands is crucial for understanding their distinct functions.
• Novel morphanone derivatives were synthesized to explore sigma receptor interactions.

Purpose of the Study:

• To investigate the sigma (σ) subtype selectivity of four novel morphanone-class ligands.
• To determine the enantioselectivity of these ligands at σ1 and σ2 receptors.
• To evaluate the potential of these compounds as research tools for σ2 receptor characterization.

Main Methods:

• Synthesis of four novel morphanone derivatives: CB-64L, CB-64D, CB-182, and CB-184.
• Radioligand binding assays to determine inhibition constants (Ki) at σ1 and σ2 receptors.
• Assessment of affinity for mu (μ) opioid receptors.

Main Results:

• CB-64L and CB-182 ((-) enantiomers) showed higher affinity for σ1 receptors.
• CB-64D and CB-184 ((+) enantiomers) displayed higher affinity for σ2 receptors.
• CB-64D and CB-184 demonstrated significant selectivity for σ2 over σ1 receptors (185-fold and 554-fold, respectively).
• Opposite enantioselectivity was observed: (-) > (+) for σ1, and (+) > (-) for σ2.
• High affinity for mu opioid receptors was noted for CB-64D and CB-184.

Conclusions:

• The novel morphanone ligands exhibit distinct enantioselectivity profiles for σ1 and σ2 receptors.
• CB-64D and CB-184 are potent and selective σ2 receptor ligands, despite some mu opioid receptor affinity.
• These compounds serve as valuable pharmacological tools for further investigating σ2 receptor function and distribution.