Design, synthesis and biological activity evaluation of desloratadine analogues as H1 receptor antagonists

Discovery of the novel and potent histamine H1 receptor antagonists for treatment of allergic diseases

Desloratadine, a second-generation histamine H1 receptor antagonist, has established itself as a first-line drug for the treatment of allergic diseases. Despite its effectiveness, desloratadine exhibits an antagonistic effect on muscarinic M3 receptor, which can cause side effects such as dry mouth and urinary retention, ultimately limiting its clinical application. Herein, we describe the discovery of compound Ⅲ-4, a novel H1 receptor antagonist with significant H1 receptor antagonistic activity (IC50 = 24.12 nM) and enhanced selectivity towards peripheral H1 receptor. In particular, Ⅲ-4 exhibits reduced M3 receptor inhibitory potency (IC50 > 10,000 nM) and acceptable hERG inhibitory activity (17.6 ± 2.1 μM) compare with desloratadine. Additionally, Ⅲ-4 exhibits favorable pharmacokinetic properties, as well as in vivo efficacy and safety profiles. All of these reveal that Ⅲ-4 has potential to emerge as a novel H1 receptor antagonist for the treatment of allergic diseases. More importantly, the compound Ⅲ-4 (HY-078020) has recently been granted clinical approval.

Computational Analysis of Structure-Based Interactions for Novel H₁-Antihistamines

As a chronic disorder, insomnia affects approximately 10% of the population at some time during their lives, and its treatment is often challenging. Since the antagonists of the H₁ receptor, a protein prevalent in human central nervous system, have been proven as effective therapeutic agents for treating insomnia, the H₁ receptor is quite possibly a promising target for developing potent anti-insomnia drugs. For the purpose of understanding the structural actors affecting the antagonism potency, presently a theoretical research of molecular interactions between 129 molecules and the H₁ receptor is performed through three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques. The ligand-based comparative molecular similarity indices analysis (CoMSIA) model (Q² = 0.525, R²ncv = 0.891, R²pred = 0.807) has good quality for predicting the bioactivities of new chemicals. The cross-validated result suggests that the developed models have excellent internal and external predictability and consistency. The obtained contour maps were appraised for affinity trends for the investigated compounds, which provides significantly useful information in the rational drug design of novel anti-insomnia agents. Molecular docking was also performed to investigate the mode of interaction between the ligand and the active site of the receptor. Furthermore, as a supplementary tool to study the docking conformation of the antagonists in the H₁ receptor binding pocket, molecular dynamics simulation was also applied, providing insights into the changes in the structure. All of the models and the derived information would, we hope, be of help for developing novel potent histamine H₁ receptor antagonists, as well as exploring the H₁-antihistamines interaction mechanism.