Novel Macrocyclic Antagonists of the CGRP Receptor Part 2: Stereochemical Inversion Induces an Unprecedented Binding Mode.

The diastereomeric macrocyclic calcitonin gene-related peptide (CGRP) antagonists HTL0029881 (3) and HTL0029882 (4), in which the stereochemistry of a spiro center is reversed, surprisingly demonstrate comparable potency. X-ray crystallographic characterization demonstrates that 3 binds to the CGRP receptor in a precedented manner but that 4 binds in an unprecedented, unexpected, and radically different manner. The observation of this phenomenon is noteworthy and may open novel avenues for CGRP receptor antagonist design.

Novel Macrocyclic Antagonists of the Calcitonin Gene-Related Peptide Receptor: Design, Realization, and Structural Characterization of Protein-Ligand Complexes.

A series of macrocyclic calcitonin gene-related peptide (CGRP) receptor antagonists identified using structure-based design principles, exemplified by HTL0028016 (1) and HTL0028125 (2), is described. Structural characterization by X-ray crystallography of the interaction of two of the macrocycle antagonists with the CGRP receptor ectodomain is described, along with structure-activity relationships associated with point changes to the macrocyclic antagonists. The identification of non-peptidic/natural product-derived, macrocyclic ligands for a G protein coupled receptor (GPCR) is noteworthy.

Discovery and Optimization of Orally Bioavailable Phthalazone and Cinnolone Carboxylic Acid Derivatives as S1P2 Antagonists against Fibrotic Diseases.

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease. Current treatments only slow down disease progression, making new therapeutic strategies compelling. Increasing evidence suggests that S1P2 antagonists could be effective agents against fibrotic diseases. Our compound collection was mined for molecules possessing substructure features associated with S1P2 activity. The weakly potent indole hit 6 evolved into a potent phthalazone series, bearing a carboxylic acid, with the aid of a homology model. Suboptimal pharmacokinetics of a benzimidazole subseries were improved by modifications targeting potential interactions with transporters, based on concepts deriving from the extended clearance classification system (ECCS). Scaffold hopping, as a part of a chemical enablement strategy, permitted the rapid exploration of the position adjacent to the carboxylic acid. Compound 38, with good pharmacokinetics and in vitro potency, was efficacious at 10 mg/kg BID in three different in vivo mouse models of fibrotic diseases in a therapeutic setting.

Macrolide Inspired Macrocycles as Modulators of the IL-17A/IL-17RA Interaction.

Interleukin 17 (IL-17) cytokines promote inflammatory pathophysiology in many autoimmune diseases, including psoriasis, multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease. Such broad involvement of IL-17 in various autoimmune diseases makes it an ideal target for drug discovery. Psoriasis is a chronic inflammatory disease characterized by numerous defective components of the immune system. Significantly higher levels of IL-17A have been noticed in lesions of psoriatic patients, if compared to non-lesion parts. Therefore, this paper is focused on the macrolide inspired macrocycles as potential IL-17A/IL-17RA modulators and covers the molecular design, synthesis, and in vitro profiling. Macrocycles are designed to diversify and enrich chemical space through different ring sizes and a variety of three-dimensional shapes. Inhibitors in the nM range were identified in both target-based and phenotypic assays. In vitro ADME as well as in vivo PK properties are reported.

Antimalarial activity of 9a-N substituted 15-membered azalides with improved in vitro and in vivo activity over azithromycin.

Novel classes of antimalarial drugs are needed due to emerging drug resistance. Azithromycin, the first macrolide investigated for malaria treatment and prophylaxis, failed as a single agent and thus novel analogues were envisaged as the next generation with improved activity. We synthesized 42 new 9a-N substituted 15-membered azalides with amide and amine functionalities via simple and inexpensive chemical procedures using easily available building blocks. These compounds exhibited marked advances over azithromycin in vitro in terms of potency against Plasmodium falciparum (over 100-fold) and high selectivity for the parasite and were characterized by moderate oral bioavailability in vivo. Two amines and one amide derivative showed improved in vivo potency in comparison to azithromycin when tested in a mouse efficacy model. Results obtained for compound 6u, including improved in vitro potency, good pharmacokinetic parameters, and in vivo efficacy higher than azithromycin and comparable to chloroquine, warrant its further development for malaria treatment and prophylaxis.

An automated, polymer-assisted strategy for the preparation of urea and thiourea derivatives of 15-membered azalides as potential antimalarial chemotherapeutics.

A series of 15-membered azalide urea and thiourea derivatives has been synthesized and evaluated for their in vitro antimalarial activity against chloroquine-sensitive (D6), chloroquine/pyremethamine resistant (W2) and multidrug resistant (TM91C235) strains of Plasmodium falciparum. We have developed an effective automated synthetic strategy for the rapid synthesis of urea/thiourea libraries of a macrolide scaffold. Compounds have been synthesized using a solution phase strategy with overall yields of 50-80%. Most of the synthesized compounds had inhibitory effects. The top 10 compounds were 30-65 times more potent than azithromycin, an azalide with antimalarial activity, against all three strains.