ABSTRACT
The inhibition of LTB(4) binding to and activation of G-protein-coupled receptors BLT1 and BLT2 is the premise of a treatment for several inflammatory diseases. In a lead optimization effort starting with the leukotriene B(4) (LTB(4)) receptor antagonist (2), members of a series of 3,5-diarylphenyl ethers were found to be highly potent inhibitors of LTB(4) binding to BLT1 and BLT2 receptors, with varying levels of selectivity depending on the substitution. In addition, compounds 33 and 38 from this series have good in vitro ADME properties, good oral bioavailability, and efficacy after oral delivery in guinea pig LTB(4) and nonhuman primate allergen challenge models. Further profiling in a rat non-GLP toxicity experiment provided the rationale for differentiation and selection of one compound (33) for clinical development.
Subject(s)
Drug Discovery , Leukotriene Antagonists/chemistry , Phenyl Ethers/pharmacology , Receptors, Leukotriene B4/antagonists & inhibitors , Animals , Drug Evaluation, Preclinical , Guinea Pigs , HL-60 Cells , Humans , Leukotriene Antagonists/pharmacology , Phenyl Ethers/chemistry , Primates , Protein Binding , Rats , Receptors, G-Protein-Coupled/metabolism , Receptors, Leukotriene B4/metabolism , Structure-Activity RelationshipABSTRACT
Asthma, chronic obstructive pulmonary disease (COPD) and acute lung injury/acute respiratory distress syndrome (ALI/ARDS) are characterized by neutrophilic inflammation and elevated levels of leukotriene B4 (LTB4). However, the exact role of LTB4 pathways in mediating pulmonary neutrophilia and the potential therapeutic application of LTB4 receptor antagonists in these diseases remains controversial. Here we show that a novel dual BLT1 and BLT2 receptor antagonist, RO5101576, potently inhibited LTB4-evoked calcium mobilization in HL-60 cells and chemotaxis of human neutrophils. RO5101576 significantly attenuated LTB4-evoked pulmonary eosinophilia in guinea pigs. In non-human primates, RO5101576 inhibited allergen and ozone-evoked pulmonary neutrophilia, with comparable efficacy to budesonide (allergic responses). RO5101576 had no effects on LPS-evoked neutrophilia in guinea pigs and cigarette smoke-evoked neutrophilia in mice and rats. In toxicology studies RO5101576 was well-tolerated. Theses studies show differential effects of LTB4 receptor antagonism on neutrophil responses in vivo and suggest RO5101576 may represent a potential new treatment for pulmonary neutrophilia in asthma.
Subject(s)
Benzodioxoles/pharmacology , Phenylpropionates/pharmacology , Pneumonia/drug therapy , Primates , Receptors, Leukotriene B4/antagonists & inhibitors , Animals , Benzodioxoles/therapeutic use , Benzodioxoles/toxicity , Dogs , Drug-Related Side Effects and Adverse Reactions , Female , Guinea Pigs , HL-60 Cells , Humans , Hypersensitivity/complications , Lipopolysaccharides/pharmacology , Lung/drug effects , Male , Mice , Ozone/pharmacology , Phenylpropionates/therapeutic use , Phenylpropionates/toxicity , Pneumonia/chemically induced , Pneumonia/complications , Pneumonia/metabolism , Rats , Receptors, Leukotriene B4/metabolism , Smoking/adverse effects , Toxicity TestsABSTRACT
Two libraries of hMC4R agonists, X-Y-DPhe(7)-Arg(8)-2-Nal(9)-Z-NH(2) and X-Y-DPhe(7)-Arg(8)-Trp(9)-Z-NH(2), totaling 185 peptides were prepared using Irori radiofrequency tagging technology and Argonaut Quest 210 Synthesizer, where X stands for N-caps, Y for His(6) surrogates and Z for Gly(10) surrogates. As a result of this study, His-modified pentapeptides with Trp were found to be more hMC4R potent than the corresponding 2-Nal analogs, novel N-caps and Gly surrogates were identified and 19 new peptides which are potent hMC4R agonists (EC(50) 1-15nM) and selective against hMC1R were discovered.
Subject(s)
Oligopeptides/chemical synthesis , Peptide Library , Receptor, Melanocortin, Type 4/agonists , Amino Acid Sequence , Glycine , Humans , Oligopeptides/chemistry , Oligopeptides/pharmacology , Structure-Activity RelationshipABSTRACT
Linear pentapeptides (Penta-cis-Apc-DPhe-Arg-Trp-Gly-NH2) containing 1-amino-4-phenylcyclohexane-1-carboxylic acid (cis-Apc) and substituted Apc are potent hMC4R agonists and they are inactive or weakly active in hMC1R, hMC3R, and hMC5R agonist assays. This study, together with our earlier report on 5-BrAtc, demonstrated the importance of replacing His6 with phenyl-containing rigid templates in achieving good hMC4R agonist potency and selectivity against hMC1R in linear pentapeptides.
Subject(s)
Carboxylic Acids/chemistry , Carboxylic Acids/pharmacology , Cyclohexanes/chemistry , Cyclohexanes/pharmacology , Receptor, Melanocortin, Type 1/agonists , Receptor, Melanocortin, Type 4/agonists , Amino Acid Sequence , Humans , Inhibitory Concentration 50 , Molecular Structure , Sensitivity and Specificity , Substrate SpecificityABSTRACT
A series of pentapeptides, based on hMC4R pentapeptide agonist (Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2)), was prepared in which either DPhe(7) or Trp(9) residue was systematically substituted. A number of interesting DPhe surrogates (D-Thi, D-3-CF(3)Phe, D-2-Nal and D-3,4-diClPhe) as well as Trp surrogates (2-Nal and Bta) were identified in this study.
Subject(s)
Oligopeptides/pharmacology , Receptor, Melanocortin, Type 4/agonists , Receptors, Melanocortin/agonists , Amino Acid Substitution , Cell Line , Humans , Obesity/drug therapy , Oligopeptides/chemistry , Receptor, Melanocortin, Type 4/genetics , Receptors, Melanocortin/genetics , Structure-Activity Relationship , TransfectionABSTRACT
A series of MT-II related cyclic peptides, based on potent but non-selective hMC4R agonist (Penta-c[Asp-His(6)-DPhe(7)-Arg(8)-Trp(9)-Lys]-NH(2)) was prepared in which His(6) residue was systematically substituted. Two of the most interesting peptides identified in this study are Penta-c[Asp-5-ClAtc-DPhe-Arg-Trp-Lys]-NH(2) and Penta-c[Asp-5-ClAtc-DPhe-Cit-Trp-Lys]-NH(2) which are potent hMC4R agonists and are either inactive or weak partial agonists (not tested for their antagonist activities) in hMC1R, hMC3R and hMC5R agonist assays.
Subject(s)
Histidine/chemistry , Receptors, Corticotropin/agonists , Amino Acid Substitution , Cell Survival/drug effects , Humans , Magnetic Resonance Spectroscopy , Peptides, Cyclic/chemical synthesis , Peptides, Cyclic/pharmacology , Receptor, Melanocortin, Type 4 , Receptors, Melanocortin , Structure-Activity Relationship , Tumor Cells, CulturedABSTRACT
Systematic substitution of His(6) residue using non-selective hMC4R pentapeptide agonist (Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2)) as the template led to the identification of Bu-Atc(6)(2-aminotetraline-2-carboxylic acid)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) which showed moderate selectivity towards hMC4R over hMC1R. Further SAR studies resulted in the discovery of Penta-5-BrAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) and Penta-5-Me(2)NAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) which are potent hMC4R agonists and are inactive in hMC1R, hMC3R and hMC5R agonist assays.
Subject(s)
Oligopeptides/chemical synthesis , Receptors, Corticotropin/agonists , Amino Acid Sequence , Amino Acid Substitution , Cyclic AMP/biosynthesis , Histidine , Humans , Oligopeptides/metabolism , Oligopeptides/pharmacology , Protein Binding , Receptor, Melanocortin, Type 4 , Receptors, Corticotropin/metabolism , Receptors, Melanocortin , Structure-Activity RelationshipABSTRACT
A series of pentapeptides, based on Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) and modified at the Arg(8) position, was prepared and pharmacologically characterized. Peptides containing either cyanoguanidine or acylguanidine, two substantially less basic arginine surrogates, were found to retain the agonist activity of the parent peptide at both hMC1R and hMC4R. This study unequivocally shows that the positive charge of Arg(8) is not essential for efficient interactions of our pentapeptide with both hMC1R and hMC4R.