Structure-Based Virtual Screening for Dopamine D2 Receptor Ligands as Potential Antipsychotics.

Area of Science:

• Neuroscience
• Pharmacology
• Medicinal Chemistry

Background:

• Dopamine D2 receptors are key targets for antipsychotic drug development.
• Traditional D2 receptor ligands often interact with a conserved Asp(3.32) residue via a protonatable nitrogen atom.
• Novel pharmacophores are needed to develop antipsychotics with improved efficacy and reduced side effects.

Purpose of the Study:

• To identify novel dopamine D2 receptor ligands with potential antipsychotic activity using structure-based virtual screening.
• To explore compounds with unique structural features and binding mechanisms.
• To assess the selectivity and affinity of identified ligands for D2 receptors.

Main Methods:

• Structure-based virtual screening of a large compound library (6.5 million) using a D2 receptor homology model.
• Experimental validation of selected compounds for D2 receptor binding.
• Affinity (Ki values) and selectivity profiling against other receptors, including D3 and 5-HT2A.
• Similarity and fragment analysis for structural novelty.
• In-depth characterization of a novel D2 antagonist, including derivative testing.

Main Results:

• Ten D2 ligands were identified from 21 tested compounds, demonstrating a 47.6% success rate.
• Identified ligands exhibited affinities ranging from 58 nM to 24 μM.
• Several compounds showed affinity for other receptors, notably 5-HT2A receptors.
• A novel D2 receptor antagonist lacking a protonatable nitrogen atom was discovered.
• This antagonist displayed >20-fold selectivity for D2 over D3 receptors.
• Evidence suggests an amide hydrogen bond interaction with Asp(3.32) in the novel antagonist.

Conclusions:

• Structure-based virtual screening is effective for discovering novel D2 receptor ligands.
• Novel antipsychotic candidates with potential for high D2 receptor selectivity were identified.
• The discovery of a D2 antagonist interacting via an amide hydrogen bond expands the understanding of D2 receptor pharmacophores.
• These findings offer new avenues for developing more effective and selective antipsychotic medications.