ABSTRACT
By use of a solid-phase synthetic approach, a bioactive reverse turn heterocycle was incorporated into a cyclic peptide template to probe melanocortin receptor potency and ligand structural conformations. The five melanocortin receptor isoforms (MC1R-MC5R) are G-protein-coupled receptors (GPCRs) that are regulated by endogenous agonists and antagonists. This pathway is involved in pigmentation, weight, and energy homeostasis. Herein, we report novel analogues of the chimeric AGRP-melanocortin peptide template integrated with a small molecule moiety to probe the structural and functional consequences of the core His-Phe-Arg-Trp peptide domain using a reverse-turn heterocycle. A series of six compounds are reported that result in inactive to full agonists with nanomolar potency. Biophysical structural analysis [2D (1)H NMR and computer-assisted molecular modeling (CAMM)] were performed on selected analogues, resulting in the identification that these peptide-small molecule hybrids possessed increased flexibility and fewer discrete conformational families compared to the reference peptide and result in a novel template for further structure-function studies.
Subject(s)
Agouti-Related Protein/chemistry , Heterocyclic Compounds, 1-Ring/chemical synthesis , Melanocortins/chemistry , Oligopeptides/chemical synthesis , Peptides, Cyclic/chemical synthesis , Peptidomimetics/chemical synthesis , Receptors, Melanocortin/agonists , Amino Acid Sequence , Animals , HEK293 Cells , Heterocyclic Compounds, 1-Ring/chemistry , Heterocyclic Compounds, 1-Ring/pharmacology , Humans , Ligands , Magnetic Resonance Spectroscopy , Mice , Models, Molecular , Molecular Conformation , Molecular Sequence Data , Oligopeptides/chemistry , Oligopeptides/pharmacology , Peptide Fragments/chemical synthesis , Peptide Fragments/chemistry , Peptide Fragments/pharmacology , Peptides, Cyclic/chemistry , Peptides, Cyclic/pharmacology , Peptidomimetics/chemistry , Peptidomimetics/pharmacology , Protein Structure, Secondary , Receptors, Melanocortin/chemistry , Stereoisomerism , Structure-Activity Relationship , Sulfides/chemical synthesis , Sulfides/chemistry , Sulfides/pharmacologyABSTRACT
The melanocortin system consists of five seven-transmembrane spanning G-protein coupled receptors (MC1-5) that are stimulated by endogenous agonists and antagonized by the only two known endogenous antagonists of GPCRs, agouti and agouti-related protein (AGRP). These receptors have been associated with many physiological functions, including the involvement of the MC4R in feeding behavior and energy homeostasis, making this system an attractive target for the treatment of obesity. Small-molecule mimetics of endogenous ligands may result in the development of compounds with properties more suitable for use as therapeutic agents. The research presented herein involves the synthesis and analysis of 12 melanocortin receptor agonists using the 1,4-benzodiazepine-2,5-dione template and is the first report of these derivatives as melanocortin receptor agonists. Structure-activity relationship studies using this privileged structure template has resulted in molecules with molecular weights around 400 that possess nanomolar agonist potency at the melanocortin receptors examined in this study.
Subject(s)
Benzodiazepines/chemical synthesis , Receptors, Melanocortin/agonists , Benzodiazepines/chemistry , Benzodiazepines/pharmacology , Cell Line , Genes, Reporter , Humans , Ligands , Structure-Activity Relationship , beta-Galactosidase/geneticsABSTRACT
[Chemical reaction: See text] Benzotriazole reagents for thioacylation (RCSBt), thiocarbamoylation (RR'NCSBt), aryl/alkoxythioacylation (ROCSBt), and aryl/alkylthiothioacylation (RSCSBt) are synthesized, and their utility is assessed by syntheses of representative heteroaryl thioureas 3a-g, thioamides 15a-s, thionoesters 16a-h, thiocarbamates 17a-e, dithiocarbamates 18a-d, thiocarbonates 19a-c, and dithiocarbonates 20a-c.
ABSTRACT
1-(Alkyl/arylthiocarbamoyl)benzotriazoles 4a-i were synthesized in yields of 91-99% from bis(benzotriazolyl)methanethione (3). Reagents 4a-g were then used as isothiocyanate equivalents for the efficient synthesis of 10 secondary and 14 tertiary thioureas in high-yielding, convenient processes.
