Virtual Screening, Synthesis and In Vitro Characterization of Histamine H₄ Receptor Ligands Based on Pyrimidine...

Area of Science:

• Medicinal Chemistry
• Pharmacology
• Drug Discovery

Background:

• Histamine receptors (H1R-H4R) are G protein-coupled receptors and therapeutic targets.
• The H4 receptor (H4R) plays a crucial role in inflammation and cancer.
• Developing selective H4R ligands is essential for therapeutic intervention.

Purpose of the Study:

• To design, synthesize, and characterize novel H4R ligands.
• To evaluate the in silico, in vitro affinity, and functional activity of new compounds.
• To investigate ligand-dependent biased signaling at the H4R.

Main Methods:

• In silico docking to the human inactive H4R structure.
• Synthesis and characterization of pyrido[2,3-d]pyrimidine and pyrimidine derivatives.
• In vitro assays including radioligand displacement, cytotoxicity (PrestoBlue), antiproliferative (BrdU), cAMP inhibition, and β-arrestin recruitment assays.

Main Results:

• Several pyrido[2,3-d]pyrimidine derivatives and one pyrimidine analog demonstrated significant H4R affinity (>60% inhibition at 1 µM).
• Tested compounds showed no significant cytotoxicity or antiproliferative effects at relevant concentrations.
• Two lead compounds, including YAN-153, acted as moderate H4R antagonists in the G-protein pathway but exhibited divergent profiles in the β-arrestin pathway, indicating biased agonism.

Conclusions:

• The study identified novel H4R ligands with potential therapeutic applications.
• YAN-153 is a promising lead structure for further optimization.
• Findings highlight ligand-dependent biased signaling at the H4R, offering new insights for drug development.