Development of Central Nervous System-Penetrant Apelin Receptor Agonists

Area of Science:

• Pharmacology
• Endocrinology
• Medicinal Chemistry

Background:

• The apelinergic system, including the apelin receptor (APLNR), is a therapeutic target for metabolic syndrome and insulin resistance.
• Existing small-molecule APLNR agonists lack sufficient central nervous system (CNS) penetration for effective therapeutic use.
• Novel CNS-penetrant compounds are needed to modulate the apelinergic system for metabolic disorders.

Purpose of the Study:

• To discover and characterize novel CNS-penetrant apelin receptor (APLNR) agonists.
• To identify biased agonists that favor G-protein signaling over β-arrestin 2 recruitment.
• To evaluate the therapeutic potential of these compounds in a preclinical model of insulin resistance.

Main Methods:

• Synthesis and screening of pyrazole- and imidazole-based compounds for APLNR agonism.
• Assessment of CNS penetration and signaling bias (G-protein vs. β-arrestin 2) for identified agonists.
• Pharmacokinetic profiling and oral activity assessment.
• In vivo efficacy studies in obese diabetic mouse models.

Main Results:

• Discovery of a novel series of APLNR agonists, including pyrazole and imidazole derivatives.
• Identification of imidazole compound 35 as a potent, CNS-penetrant, biased APLNR agonist with an ~8-fold G-protein signaling preference.
• Compound 35 demonstrated favorable oral pharmacokinetics and was orally active.
• Treatment with compound 35 significantly improved insulin resistance in obese diabetic mice.

Conclusions:

• Compound 35 represents a promising CNS-penetrant, biased APLNR agonist for treating insulin resistance.
• The discovery highlights the potential of targeting the apelinergic system with novel small molecules for metabolic diseases.
• Biased agonism at APLNR may offer a therapeutic strategy with an improved efficacy and safety profile.