Discovery of highly potent and selective biphenylacylsulfonamide-based beta3-adrenergic receptor agonists and molecular modeling based on the solved X-ray structure of the beta2-adrenergic receptor: part 6

KLİNİKTE ÖNEMLİ OLAN KATEKOLAMİN VE TÜREVLERİNİN YAPILARININ İNCELENMESİ

Amaç: Katekolaminler olarak adlandırılan monoamin yapısındaki 3,4-dihidroksifeniletilamin türevi dopamin, epinefrin ve norepinefrin, çok önemli biyolojik rolleri olan endojen bileşiklerdir. Katekol yapısı taşıyan bu biyomoleküllerin, kendine özgü reseptörleri uyararak, organizmadaki pek çok sistemi kontrol ettiği bilinmektedir. Özellikle bu endojen bileşiklerin, adrenerjik ve dopaminerjik sistem üzerinden uyarıcı etkilerinin olduğu görülmektedir. Pek çok biyolojik süreçte hormon veya nörotransmitter olarak yer alan bu bileşikler, terapötik önemleri nedeniyle sentetik olarak da elde edilerek klinikte kullanılmaktadır. Ayrıca, endojen katekolaminlerin farmakolojik ve farmasötik özelliklerini iyileştirmek amacıyla, kimyasal modifikasyonlar ile yeni pek çok türevi geliştirilmiştir. Klinikteki kullanımlarının geniş ve önemli olması, bu bileşikleri araştırmacılar için değerli kılmaktadır. Katekolamin ve türevi bileşiklerin aktivitelerinin incelenmesi kadar kimyasal yapılarının anlaşılması ve sentez yöntemlerinin araştırılması da yeni türevlerin geliştirilmesi açısından çok önemlidir. Sonuç ve Tartışma: Bu nedenle bu çalışmada klinik önemleri olan katekolamin türevlerinin yapıları ve özellikleri araştırılmıştır. Çalışma sonucunda katekolaminlerin kimyasal özellikleri, biyosentezleri ve sentetik olarak elde edilme yöntemleri ile biyolojik aktiviteleri ve klinikteki kullanımları ortaya konulmuştur.

Discovery of Novel Indazole Derivatives as Orally Available β3-Adrenergic Receptor Agonists Lacking Off-Target-Based Cardiovascular Side Effects

We previously discovered that indazole derivative 8 was a highly selective β₃-adrenergic receptor (β₃-AR) agonist, but it appeared to be metabolically unstable. To improve metabolic stability, further optimization of this scaffold was carried out. We focused on the sulfonamide moiety of this scaffold, which resulted in the discovery of compound 15 as a highly potent β₃-AR agonist (EC₅₀ = 18 nM) being inactive to β₁-, β₂-, and α_1A-AR (β₁/β₃, β₂/β₃, and α_1A/β₃ > 556-fold). Compound 15 showed dose-dependent β₃-AR-mediated responses in marmoset urinary bladder smooth muscle, had a desirable metabolic stability and pharmacokinetic profile (C_max and AUC), and did not obviously affect heart rate or mean blood pressure when administered intravenously (3 mg/kg) to anesthetized rats. Thus, compound 15 is a highly potent, selective, and orally available β₃-AR agonist, which may serve as a candidate drug for the treatment of overactive bladder without off-target-based cardiovascular side effects.

Structure-based drug design for G protein-coupled receptors

Our understanding of the structural biology of G protein-coupled receptors has undergone a transformation over the past 5 years. New protein-ligand complexes are described almost monthly in high profile journals. Appreciation of how small molecules and natural ligands bind to their receptors has the potential to impact enormously how medicinal chemists approach this major class of receptor targets. An outline of the key topics in this field and some recent examples of structure- and fragment-based drug design are described. A table is presented with example views of each G protein-coupled receptor for which there is a published X-ray structure, including interactions with small molecule antagonists, partial and full agonists. The possible implications of these new data for drug design are discussed.

Catecholamine receptors: prototypes for GPCR-based drug discovery

Drugs acting at G protein-coupled receptors (GPCRs) constitute ~40% of those in current clinical use. GPCR-based drug discovery remains at the forefront of drug development, especially for new treatments for psychiatric illness and neurological disease. Here, the basic framework of GPCR signaling learned through the elucidation of catecholamine receptor signaling through G proteins and β-arrestins, and X-ray crystallographic structure determination is reviewed. In silico docking studies developed in tandem with confirmatory empirical data gathering from binding and signaling experiments have allowed this basic framework to be expanded to drug hunting through predictive in silico searching as well as high-throughput and high-content screening approaches. For efforts moving forward for the deployment of new GPCR-acting drugs, collaborative efforts between industry and government/academic research in target validation at the molecular and cellular levels have become progressively more common. Polypharmacological approaches have become increasingly available for learning more about the mechanisms of GPCR-targeted drugs, based on interaction not with a single, but with a wide range of GPCR targets. These approaches are likely to aid in drug repurposing efforts, yield valuable insight on the side effects of currently employed drugs, and allow for a clearer picture of the actual targets of "atypical" drugs used in a variety of therapeutic contexts.

The use of GPCR structures in drug design

Structure-based drug discovery is routinely applied to soluble targets such as proteases and kinases. It is only recently that multiple high-resolution X-ray structures of G protein-coupled receptors (GPCRs) have become available. Here we review the technology developments that have led to the recent plethora of GPCR structures. These include developments in protein expression and purification as well as techniques to stabilize receptors and crystallize them. We discuss the findings derived from the new structures with regard to understanding GPCR function and pharmacology. Finally, we examine the utility of structure-based drug discovery approaches including homology modeling, virtual screening, and fragment screening for GPCRs in the context of what has been learnt from other target classes.

Beyond rhodopsin: G protein-coupled receptor structure and modeling incorporating the beta2-adrenergic and adenosine A(2A) crystal structures

For quite some time, the majority of GPCR models have been based on a single template structure: dark-adapted bovine rhodopsin. The recent solution of β2AR, β1AR and adenosine A(2A) receptor crystal structures has dramatically expanded the GPCR structural landscape and provided many new insights into receptor conformation and ligand binding. They will serve as templates for the next generation of GPCR models, but also allow direct validation of previous models and computational techniques. This review summarizes key findings from the new structures, comparison of existing models to these structures and highlights new models constructed from these templates.