ABSTRACT
Stereospecific introduction of a methyl group to the indole-3-side chain enhanced activity in our tryptamine-derived series of GnRH receptor antagonists. Further improvements were achieved by variation of the bicyclic amino moiety of the tertiary amide and by adjustment of the tether length to a pyridine or pyridone terminus. These modifications culminated in analogue 24, which had oral activity in a rat model and acceptable oral bioavailability and half-life in dogs and monkeys.
Subject(s)
Indoles/pharmacokinetics , Receptors, LHRH/antagonists & inhibitors , Tryptamines/pharmacokinetics , Administration, Oral , Animals , Biological Availability , Dogs , Indoles/chemical synthesis , Indoles/chemistry , Indoles/pharmacology , Luteinizing Hormone/metabolism , Macaca mulatta , Models, Animal , Rats , Structure-Activity Relationship , Tryptamines/chemical synthesis , Tryptamines/chemistry , Tryptamines/pharmacologyABSTRACT
The 2-aryltryptamine class of GnRH receptor antagonists has been modified to incorporate carboxamide and acetamide substituents at the indole 5-position. With either a phenol or methanesulfonamide terminus on the N-aralkyl side chain, potent binding affinity to the GnRH receptor was achieved. A functional assay for GnRH antagonism was even more sensitive to structural modification and revealed a strong preference for branched tertiary amides.
Subject(s)
Amides/chemistry , Indoles/pharmacology , Receptors, LHRH/antagonists & inhibitors , Indoles/chemistry , Indoles/metabolism , Protein Binding , Receptors, LHRH/metabolismABSTRACT
A pyridine side-chain terminus has been incorporated into the indole-5-carboxamide and indole-5-acetamide series of GnRH antagonists. Potent activity was observed in binding and functional assays. Certain branched or cyclic tertiary amides were identified as preferred in each series. Alkylation of the side-chain secondary amine had generally unfavorable effects. Variations of the gem-dialkyl substituents in the indole-5-acetamide series were also investigated.
Subject(s)
Amides/chemistry , Indoles/pharmacology , Pyridines/chemistry , Receptors, LHRH/antagonists & inhibitors , Animals , CHO Cells , Cricetinae , Humans , Indoles/chemistry , RatsABSTRACT
A series of 2-(3,5-dimethylphenyl)tryptamine derivatives was prepared and evaluated on a rat gonadotropin releasing hormone receptor assay. Some para-substituents on the 4-phenylbutyl side chain attached to the tryptamine nitrogen led to compounds with potent GnRH receptor binding. The study has helped define structural requirements for GnRH receptor binding for the 2-aryltryptamine GnRH antagonists.
Subject(s)
Hormone Antagonists/metabolism , Hormone Antagonists/pharmacology , Receptors, LHRH/metabolism , Tryptamines/chemical synthesis , Tryptamines/metabolism , Tryptamines/pharmacology , Animals , Binding Sites/physiology , Drug Design , Female , Hormone Antagonists/chemistry , Humans , Inhibitory Concentration 50 , Molecular Structure , Rats , Tryptamines/chemistryABSTRACT
A series of heterocyclic 2-(3,5-dimethylphenyl)tryptamine derivatives was prepared and evaluated on a rat gonadotropin releasing hormone receptor assay. The carbon tether length and heterocyclic ring attached to the amino group of 2-(3,5-dimethylphenyl)tryptamine were varied. Several of these derivatives were potent GnRH antagonists with the most potent compound having an IC50 of 16 nM.
Subject(s)
Heterocyclic Compounds/chemical synthesis , Hormone Antagonists/metabolism , Receptors, LHRH/metabolism , Tryptamines/chemical synthesis , Tryptamines/metabolism , Animals , Binding Sites/physiology , Drug Design , Female , Hormone Antagonists/chemistry , Inhibitory Concentration 50 , RatsABSTRACT
Extensive development of the structure-activity relationships of a screening lead determined three important pharmacophores for gonadotropin-releasing hormone (GnRH) receptor antagonist activity. Incorporation of the 3,4,5-trimethylphenyl group at the 3-position, 2-(2(S)-azetidinyl)ethoxy group at the 4-position, and N-4-pyrimidinylcarboxamide at the 6-position of the quinolone core resulted in the identification of 4-(2-(azetidin-2(S)-yl)ethoxy)-7-chloro-2-oxo-3-(3,4,5-trimethylphenyl)-1,2-dihydroquinoline-6-carboxylic acid pyrimidin-4-ylamide (1) as a potent antagonist of the GnRH receptor. A 10(4)-fold increase in in vitro binding affinity is observed for the GnRH receptor as compared to the initial screening lead. Compound 1 exhibits nanomolar binding activity and functional antagonism at the human receptor and is 7-fold less active at the rhesus receptor. Intravenous administration of compound 1 to rhesus monkeys results in a significant decrease of the serum levels of downstream hormones, luteinizing hormone (79% decrease in area under the curve) and testosterone (92% decrease in area under the curve), at a dose of 3 mg/kg. Quinolone 1 is a potent nonpeptidyl antagonist for the human GnRH receptor that is efficacious for the suppression of luteinizing hormone and testosterone in primates.
Subject(s)
Azetidines/chemical synthesis , Quinolones/chemical synthesis , Receptors, LHRH/antagonists & inhibitors , Animals , Azetidines/chemistry , Azetidines/pharmacokinetics , Azetidines/pharmacology , Binding, Competitive , CHO Cells , Cricetinae , Humans , In Vitro Techniques , Macaca mulatta , Pituitary Gland/metabolism , Quinolones/chemistry , Quinolones/pharmacokinetics , Quinolones/pharmacology , Radioligand Assay , Rats , Structure-Activity RelationshipABSTRACT
A nonpeptidyl GnRH receptor antagonist (1), with a unique 2-arylindole core, was identified through the Merck in-house screening for binding affinity on the rat GnRH receptor. SAR studies directed toward the alkoxy-ethanolamine and 2-aryl groups resulted in a simpler lead structure with improved activity. This compound 50 exhibits a 60-fold improvement in binding activity over our initial lead 1.
Subject(s)
Indoles/pharmacology , Receptors, LHRH/antagonists & inhibitors , Animals , Rats , Structure-Activity RelationshipABSTRACT
The discovery of the potency-enhancing effect of 5-substitutions on the novel 2-arylindoles as nonpeptidyl GnRH receptor antagonists led to the identification of several analogues with high affinities on the GnRH receptor. The syntheses and SARs of these 5-substituted-2-arylindole analogues are reported.
Subject(s)
Indoles/pharmacology , Receptors, LHRH/antagonists & inhibitors , Animals , Rats , Structure-Activity RelationshipABSTRACT
A series of 3-arylquinolones was prepared and evaluated for their ability to act as gonadotropin releasing hormone (GnRH) antagonists. A variety of substitution patterns of the 3-aryl substituent are described. The 3,4,5-trimethylphenyl substituent (23h) was found to be optimal.
Subject(s)
Gonadotropin-Releasing Hormone/antagonists & inhibitors , Quinolones/pharmacology , Quinolones/chemistry , Structure-Activity RelationshipABSTRACT
The dog GnRH receptor was cloned to facilitate the identification and characterization of selective nonpeptide GnRH antagonists. The dog receptor is 92% identical to the human GnRH receptor. Despite such high conservation, the quinolone-based nonpeptide GnRH antagonists were clearly differentiated by each receptor species. By contrast, peptide antagonist binding and functional activity were not differentiated by the two receptors. The basis of the differences was investigated by preparing chimeric receptors followed by site-directed mutagenesis. Remarkably, a single substitution of Phe313 to Leu313 in the dog receptor explained the major differences in binding affinities and functional activities. The single amino acid replacement of Phe313 of the human receptor with Leu313 resulted in a 160-fold decrease of binding affinity of the nonpeptide antagonist compound 1. Conversely, the replacement of Leu313 of the dog receptor with Phe313 resulted in a 360-fold increase of affinity for this compound. These results show that Phe313 of the GnRH receptor is critical for the binding of this structural class of GnRH antagonists and that the dog receptor can be "humanized" by substituting Leu for Phe. This study provides the first identification of a critical residue in the binding pocket occupied by nonpeptide GnRH antagonists and reinforces cautious extrapolation of ligand activity across highly conserved receptors.
Subject(s)
Gonadotropin-Releasing Hormone/antagonists & inhibitors , Hormone Antagonists/pharmacology , Oligopeptides/pharmacology , Phenylalanine/chemistry , Receptors, LHRH/chemistry , Amino Acid Sequence , Amino Acid Substitution , Animals , Binding Sites , Cloning, Molecular , Dogs , Hormone Antagonists/chemistry , Humans , Leucine/chemistry , Models, Molecular , Molecular Sequence Data , Molecular Structure , Mutagenesis, Site-Directed , Oligopeptides/chemical synthesis , Oligopeptides/chemistry , Protein Binding , Quinolones/chemistry , Receptors, LHRH/genetics , Receptors, LHRH/metabolism , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Species Specificity , Structure-Activity RelationshipABSTRACT
SAR studies which focused upon the C-6 position of a recently described series of quinolone gonadotropin releasing hormone antagonists are reported. Synthetic access to diverse quinolone-6-carboxamides was achieved via the palladium-catalyzed amino-carbonylation reactions of iodide 4 with various amines. Amides related to 9y were especially potent, functional antagonists of rat and human GnRH receptors.
Subject(s)
Amides/chemical synthesis , Quinolones/chemical synthesis , Receptors, LHRH/antagonists & inhibitors , Amides/pharmacology , Animals , CHO Cells , Cricetinae , Humans , Luteinizing Hormone/metabolism , Phosphatidylinositols/metabolism , Quinolones/pharmacology , Rats , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Screening of the Merck sample collection for non-peptide compounds with binding affinity for the rat GnRH receptor led to the identification of the substituted quinolone (1) as a lead compound in the search for a non-peptide GnRH receptor antagonist. Substantial improvements in potency (approximately 300 fold) were achieved by addition of an alkyl amine at the 4-position, a 3,5-dimethylphenyl group at the 3-position and 6-nitro-7-chloro-substitution of the 1 H-quinolone core.
Subject(s)
Quinolones/chemistry , Quinolones/pharmacology , Receptors, LHRH/antagonists & inhibitors , Animals , Protein Binding , Quinolones/metabolism , Rats , Receptors, LHRH/metabolism , Structure-Activity RelationshipABSTRACT
Synthesis and in vitro activity of the enantiomers of quinolone GnRH antagonist (+/-)-1 are reported. Chiral amino alcohols were prepared from the appropriate cyclic D- or L-amino acids by the Amdt-Eistert homologation followed by reduction of the resulting esters. Incorporation of these pharmacophores was achieved via a novel Mitsunobu alkylation of 4-hydroxyquinolones. The key amine pharmacophore for binding to the rat GnRH receptor was most active in the S-configuration. Ring size was not important for potency with 4, 5, 6, and 7-membered ring amines exhibiting similar potency.
Subject(s)
Quinolones/chemical synthesis , Receptors, LHRH/antagonists & inhibitors , Animals , Protein Binding , Quinolones/metabolism , Quinolones/pharmacology , Rats , Receptors, LHRH/metabolism , StereoisomerismABSTRACT
A tether length study of C32-O-phenalkyl ether derivatives of ascomycin was conducted wherein it was determined that a 2-carbon tether provides optimum in vitro immunosuppressive activity. Oxygen-bearing substituents along the 2-carbon tether can further increase the potency of this design.
Subject(s)
Immunosuppressive Agents/chemical synthesis , Immunosuppressive Agents/pharmacology , Macrolides/chemical synthesis , Macrolides/pharmacology , Tacrolimus/analogs & derivatives , Animals , Cell Division/drug effects , Drug Design , Drug Evaluation, Preclinical , Immunophilins/metabolism , Immunosuppressive Agents/metabolism , Inhibitory Concentration 50 , Structure-Activity Relationship , T-Lymphocytes/drug effects , Tacrolimus/chemistry , Tacrolimus/pharmacology , Tacrolimus Binding ProteinsABSTRACT
The synthesis of C32-O-arylethyl ether derivatives of ascomycin that possess equivalent immunosuppressant activity but reduced toxicity, compared to FK-506, is described.
Subject(s)
Immunosuppressive Agents/chemical synthesis , Immunosuppressive Agents/pharmacology , Macrolides/chemical synthesis , Macrolides/pharmacology , Tacrolimus/analogs & derivatives , Administration, Oral , Animals , Calcineurin Inhibitors , Drug Evaluation, Preclinical , Hypothermia/chemically induced , Immunophilins/metabolism , Immunosuppressive Agents/metabolism , Immunosuppressive Agents/toxicity , Inhibitory Concentration 50 , Injections, Intravenous , Kidney Diseases/chemically induced , Male , Mice , Mice, Inbred BALB C , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , T-Lymphocytes/drug effects , Tacrolimus/chemistry , Tacrolimus/pharmacology , Tacrolimus/toxicity , Tacrolimus Binding Proteins , Toxicity TestsABSTRACT
A series of C32-O-aralkyl ether derivatives of the FK-506 related macrolide ascomycin have been prepared based on an earlier reported C32-O-cinnamyl ether design. In the present study, the nature of the aryl tethering group was varied in an attempt to improve oral activity. An imidazol-2-yl-methyl tether was found to be superior among those investigated and has resulted in an ascomycin analog, L-733,725, with in vivo immunosuppressive activity comparable to FK-506 but with an improved therapeutic index.