ABSTRACT
A study that was designed to identify plausible replacements for highly basic guanidine moiety contained in potent MC4R agonists, as exemplified by 1, led to the discovery of initial nonguanidine lead 5. Propyl analog 23 was subsequently found to be equipotent to 5, whereas analogs bearing smaller and branched alkyl groups at the 3 position of the oxopiperazine template demonstrated reduced binding affinity and agonist potency for MC4R. Acylation of the NH2 group of the 4F-D-Phe residue of 3-propyl analog 23 significantly increased the binding affinity and the functional activity for MC4R. Analogs with neutral and weakly basic capping groups of the D-Phe residue exhibited excellent MC4R selectivity against MC1R whereas those with an amino acid had moderate MC4R/MC1R selectivity. We have also demonstrated that compound 35 showed promising oral bioavailability and a moderate oral half life and induced significant weight loss in a 28-day rat obesity model.
Subject(s)
Anti-Obesity Agents/pharmacology , Anti-Obesity Agents/therapeutic use , Obesity/drug therapy , Piperazines/pharmacology , Piperazines/therapeutic use , Receptor, Melanocortin, Type 4/agonists , Administration, Oral , Animals , Anti-Obesity Agents/chemistry , Biological Availability , Diet , Disease Models, Animal , Dogs , Drug Design , Drug Evaluation, Preclinical , Eating/drug effects , Male , Molecular Conformation , Piperazines/chemistry , Rats , StereoisomerismABSTRACT
Guided by X-ray crystallography of thrombin-inhibitor complexes and molecular modeling, alkylation of the N1 nitrogen of the imidazole P1 ligand of the pyridinoneacetamide thrombin inhibitor 1 with various acetamide moieties furnished inhibitors with significantly improved thrombin potency, trypsin selectivity, functional in vitro anticoagulant potency and in vivo antithrombotic efficacy. In the pyrazinoneacetamide series, oral bioavailability was also improved.
Subject(s)
Anticoagulants/pharmacology , Antithrombins/pharmacology , Drug Design , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Thrombin/antagonists & inhibitors , Administration, Oral , Animals , Anticoagulants/chemical synthesis , Anticoagulants/chemistry , Anticoagulants/pharmacokinetics , Antithrombins/chemical synthesis , Antithrombins/chemistry , Antithrombins/pharmacokinetics , Biological Availability , Chlorides , Crystallography, X-Ray , Dogs , Ferric Compounds/pharmacology , Imidazoles/chemistry , Imidazoles/pharmacokinetics , Macaca mulatta , Models, Molecular , Molecular Structure , Partial Thromboplastin Time , Rats , Structure-Activity Relationship , Thrombin/chemistry , Thrombin/metabolism , Trypsin/metabolismABSTRACT
Despite their relatively weak basicity, simple azoles, specifically imidazoles and aminothiazoles, can function as potent surrogates for the more basic amines (e.g., alkyl amines, amidines, guanidines, etc.) which are most often employed as the P1 ligand in the design of noncovalent small molecule inhibitors of thrombin.
Subject(s)
Azoles/pharmacology , Enzyme Inhibitors/pharmacology , Thrombin/antagonists & inhibitors , Azoles/chemistry , Drug Design , Ligands , Molecular Structure , Structure-Activity Relationship , Trypsin/drug effectsABSTRACT
The first synthesis of Tic-D-Phe Psi[CH(2)-CH(2)] isostere is described, which features diastereoselective alkylation of the tricyclic lactam 14. The use of this novel dipeptide isostere in the development of melanocortin agonists has been demonstrated by the synthesis of peptidomimetic 7 and non-peptidic ligand 27. Both compounds displayed significant binding and agonist potency at the MC4R.
