ABSTRACT
Modification of the benzo rings of 3-(1,1-dioxo-2H-(1,2,4)-benzothiadiazin-3-yl)-4-hydroxy-2(1H)-quinolinones into heteroaromatic systems was investigated to enhance physicochemical properties and potency profile of this class of inhibitors. The synthesis and biological activity of the derived compounds is discussed.
Subject(s)
Chemistry, Pharmaceutical/methods , Quinolones/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Drug Design , Genotype , Hepacivirus/metabolism , Humans , Inhibitory Concentration 50 , Models, Chemical , Molecular Structure , Protein Binding , Quinolones/pharmacology , Structure-Activity RelationshipABSTRACT
The synthesis and optimisation of HCV NS5B polymerase inhibitors with improved potency versus the existing compound 1 is described. Substitution in the benzothiadiazine portion of the molecule, furnishing improvement in potency in the high protein Replicon assay, is highlighted, culminating in the discovery of 12h, a highly potent oxyacetamide derivative.
Subject(s)
Antiviral Agents/chemical synthesis , Benzothiadiazines/chemistry , Chemistry, Pharmaceutical/methods , Hepacivirus/enzymology , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Animals , Antiviral Agents/pharmacology , Benzothiadiazines/pharmacology , Drug Design , Humans , Inhibitory Concentration 50 , Models, Chemical , Molecular Conformation , Molecular Structure , Rats , Structure-Activity RelationshipABSTRACT
SAR exploration of the central diamine, benzyl, and terminal aminoalkoxy regions of the N-cyclic azaalkyl benzamide series led to the identification of very potent human urotensin-II receptor antagonists such as 1a with a K(i) of 4 nM. The synthesis and structure-activity relationships (SAR) of N-cyclic azaalkyl benzamides are described.
Subject(s)
Benzamides/chemistry , Receptors, G-Protein-Coupled/antagonists & inhibitors , Binding Sites , Chemistry, Pharmaceutical/methods , Diamines/chemistry , Drug Design , Humans , Inhibitory Concentration 50 , Kinetics , Models, Chemical , Structure-Activity RelationshipABSTRACT
Recently, we disclosed a new class of HCV polymerase inhibitors discovered through high-throughput screening (HTS) of the GlaxoSmithKline proprietary compound collection. This interesting class of 3-(1,1-dioxo-2H-1,2,4-benzothiadiazin-3-yl)-4-hydroxy-2(1H)-quinolinones potently inhibits HCV polymerase enzymatic activity and inhibits the ability of the subgenomic HCV replicon to replicate in Huh-7 cells. This report will focus on the structure-activity relationships (SAR) of substituents on the quinolinone ring, culminating in the discovery of 1-(2-cyclopropylethyl)-3-(1,1-dioxo-2H-1,2,4-benzothiadiazin-3-yl)-6-fluoro-4-hydroxy-2(1H)-quinolinone (130), an inhibitor with excellent potency in biochemical and cellular assays possessing attractive molecular properties for advancement as a clinical candidate. The potential for development and safety assessment profile of compound 130 will also be discussed.
Subject(s)
Antiviral Agents/chemical synthesis , Benzothiadiazines/chemical synthesis , Hepacivirus/enzymology , Quinolones/chemical synthesis , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Thiadiazines/chemical synthesis , Animals , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Benzothiadiazines/chemistry , Benzothiadiazines/pharmacology , Biological Availability , Blood Proteins/metabolism , Cell Line , Crystallography, X-Ray , Dogs , Genotype , Half-Life , Hepacivirus/genetics , Macaca fascicularis , Models, Molecular , Molecular Structure , Mutation , Protein Binding , Quinolones/chemistry , Quinolones/pharmacology , RNA-Dependent RNA Polymerase/chemistry , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , Thiadiazines/chemistry , Thiadiazines/pharmacologyABSTRACT
1. SB-706375 potently inhibited [(125)I]hU-II binding to both mammalian recombinant and 'native' UT receptors (K(i) 4.7+/-1.5 to 20.7+/-3.6 nM at rodent, feline and primate recombinant UT receptors and K(i) 5.4+/-0.4 nM at the endogenous UT receptor in SJRH30 cells). 2. Prior exposure to SB-706375 (1 microM, 30 min) did not alter [(125)I]hU-II binding affinity or density in recombinant cells (K(D) 3.1+/-0.4 vs 5.8+/-0.9 nM and B(max) 3.1+/-1.0 vs 2.8+/-0.8 pmol mg(-1)) consistent with a reversible mode of action. 3. The novel, nonpeptidic radioligand [(3)H]SB-657510, a close analogue of SB-706375, bound to the monkey UT receptor (K(D) 2.6+/-0.4 nM, B(max) 0.86+/-0.12 pmol mg(-1)) in a manner that was inhibited by both U-II isopeptides and SB-706375 (K(i) 4.6+/-1.4 to 17.6+/-5.4 nM) consistent with the sulphonamides and native U-II ligands sharing a common UT receptor binding domain. 4. SB-706375 was a potent, competitive hU-II antagonist across species with pK(b) 7.29-8.00 in HEK293-UT receptor cells (inhibition of [Ca(2+)](i)-mobilization) and pK(b) 7.47 in rat isolated aorta (inhibition of contraction). SB-706375 also reversed tone established in the rat aorta by prior exposure to hU-II (K(app) approximately 20 nM). 5. SB-706375 was a selective U-II antagonist with >/=100-fold selectivity for the human UT receptor compared to 86 distinct receptors, ion channels, enzymes, transporters and nuclear hormones (K(i)/IC(50)>1 microM). Accordingly, the contractile responses induced in isolated aortae by KCl, phenylephrine, angiotensin II and endothelin-1 were unaltered by SB-706375 (1 microM). 6. In summary, SB-706375 is a high-affinity, surmountable, reversible and selective nonpeptide UT receptor antagonist with cross-species activity that will assist in delineating the pathophysiological actions of U-II in mammals.
Subject(s)
Pyrrolidines/pharmacology , Receptors, G-Protein-Coupled/antagonists & inhibitors , Receptors, G-Protein-Coupled/genetics , Sulfonamides/pharmacology , Algorithms , Animals , Aorta, Thoracic/drug effects , Binding, Competitive/drug effects , Cats , Cell Line, Tumor , Cell Membrane/metabolism , Haplorhini , Humans , In Vitro Techniques , Mice , Muscle Contraction/drug effects , Muscle, Smooth, Vascular/drug effects , Radioligand Assay , Rats , Recombinant Proteins/metabolism , Rhabdomyosarcoma/metabolism , Species SpecificityABSTRACT
High-throughput screening has resulted in the discovery of thiosemicarbazone thrombopoietin mimics. A shared pharmacophore hypothesis between this series and a previously identified class, the pyrazol-4-ylidenehydrazines, led to the rapid optimization of both potency and efficacy of the thiosemicarbazones. The application of high-throughput chemistry and purification techniques allowed for the rapid elucidation of structure-activity relationships.
Subject(s)
Aldehydes/chemical synthesis , Thiosemicarbazones/chemical synthesis , Thrombopoietin/chemistry , Aldehydes/chemistry , Aldehydes/pharmacology , Cell Division/drug effects , Cell Line , Combinatorial Chemistry Techniques , Humans , Models, Molecular , Molecular Mimicry , Phosphorylation , Recombinant Proteins/pharmacology , Structure-Activity Relationship , Thiosemicarbazones/chemistry , Thiosemicarbazones/pharmacology , Thrombopoietin/pharmacologyABSTRACT
The invention of a new class of naphtho[1,2-d]imidazole thrombopoietin mimics based on a pharmacophore hypothesis for small-molecule thrombopoietic agonists is discussed. Parallel array synthesis and purification techniques allowed for the rapid exploration of structure-activity relationships within this class and for the improvement in TPO mimetic potencies and efficacies.
Subject(s)
Imidazoles/chemical synthesis , Thrombopoietin/chemistry , Antigens, CD34/metabolism , Bone Marrow Cells/drug effects , Bone Marrow Cells/metabolism , Cell Differentiation , Cell Division/drug effects , Cell Line , Combinatorial Chemistry Techniques , Genes, Reporter , Humans , Imidazoles/chemistry , Imidazoles/pharmacology , Luciferases/genetics , Luciferases/metabolism , Models, Molecular , Molecular Mimicry , Phosphorylation , Structure-Activity Relationship , Thrombopoietin/genetics , Thrombopoietin/pharmacologyABSTRACT
Functional screening of the former SmithKline Beecham compound collection against the human calcium receptor (CaR) resulted in the identification of the amino alcohol-based hit 2 (IC(50) = 11 microM). Structure-activity studies of 2 focused on the optimization of the right- and left-hand side aromatic moieties as well as the amino alcohol linker region. Critical to the optimization of this antagonist template was the discovery that the chirality of the C-2 secondary alcohol played a key role in enhancing both CaR potency as well as selectivity over the beta-adrenergic receptor subtypes. These SAR studies ultimately led to the identification of 38 (NPS 2143; SB-262470A), a potent and orally active CaR antagonist. Pharmacokinetic characterization of 38 in the rat revealed that this molecule had a large volume of distribution (11 L/kg), which resulted in a prolonged systemic exposure, protracted increases in the plasma levels of PTH, and an overall lack of net bone formation effect in a rodent model of osteoporosis.
Subject(s)
Amino Alcohols/chemistry , Amino Alcohols/pharmacokinetics , Parathyroid Hormone/blood , Receptors, Calcium-Sensing/antagonists & inhibitors , Administration, Oral , Animals , Humans , Osteoporosis/drug therapy , Rats , Structure-Activity Relationship , Tissue DistributionABSTRACT
Overexpression of AKT has an antiapoptotic effect in many cell types, and expression of dominant negative AKT blocks the ability of a variety of growth factors to promote survival. Therefore, inhibitors of AKT kinase activity might be useful as monotherapy for the treatment of tumors with activated AKT. Herein, we describe our lead optimization studies culminating in the discovery of compound 3g (GSK690693). Compound 3g is a novel ATP competitive, pan-AKT kinase inhibitor with IC 50 values of 2, 13, and 9 nM against AKT1, 2, and 3, respectively. An X-ray cocrystal structure was solved with 3g and the kinase domain of AKT2, confirming that 3g bound in the ATP binding pocket. Compound 3g potently inhibits intracellular AKT activity as measured by the inhibition of the phosphorylation levels of GSK3beta. Intraperitoneal administration of 3g in immunocompromised mice results in the inhibition of GSK3beta phosphorylation and tumor growth in human breast carcinoma (BT474) xenografts.
Subject(s)
Oxadiazoles/pharmacology , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Animals , Female , Magnetic Resonance Spectroscopy , Mass Spectrometry , Mice , Mice, SCID , Models, Molecular , Oxadiazoles/chemistry , Oxadiazoles/metabolism , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Substrate SpecificityABSTRACT
A novel benzimidazole series of small-molecule thrombopoietin receptor agonists has been discovered. Herein, we discuss the preliminary exploration of structure-activity relationships within this chemotype.
Subject(s)
Benzimidazoles/chemistry , Benzimidazoles/pharmacology , Receptors, Cytokine/agonists , Receptors, Cytokine/metabolism , Thrombopoietin/metabolism , Acids/chemistry , Benzimidazoles/chemical synthesis , Molecular Structure , Naphthols/chemistry , Structure-Activity RelationshipABSTRACT
HTS of the compound collection for inhibition of the HCV RNA dependent RNA polymerase identified two 168 member N-acyl pyrrolidine combinatorial mixture hits. Deconvolution and expansion of these mixtures by solid phase synthesis to establish initial SAR and identify a potent inhibitor is reported.
Subject(s)
Hepacivirus/enzymology , Pyrrolidines/chemistry , Pyrrolidines/pharmacology , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Combinatorial Chemistry Techniques , Molecular StructureABSTRACT
High throughput screening of the corporate compound collection led to the discovery of a novel series of substituted aminoalkoxybenzyl pyrrolidines as human urotensin-II receptor antagonists. The synthesis, initial structure-activity relationships, and optimization of the initial hit that led to the identification of a truncated sub-series, represented by SB-436811 (1a), are described.
Subject(s)
Pyrrolidines/chemical synthesis , Receptors, G-Protein-Coupled/antagonists & inhibitors , Drug Evaluation, Preclinical , Humans , Pyrrolidines/pharmacology , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Granulocyte colony-stimulating factor regulates neutrophil production by binding to a specific receptor, the granulocyte colony-stimulating factor receptor, expressed on cells of the granulocytic lineage. Recombinant forms of granulocyte colony-stimulating factor are used clinically to treat neutropenias. As part of an effort to develop granulocyte colony-stimulating factor mimics with the potential for oral bioavailability, we previously identified a nonpeptidyl small molecule (SB-247464) that selectively activates murine granulocyte colony-stimulating factor signal transduction pathways and promotes neutrophil formation in vivo. To elucidate the mechanism of action of SB-247464, a series of cell-based and biochemical assays were performed. The activity of SB-247464 is strictly dependent on the presence of zinc ions. Titration microcalorimetry experiments using a soluble murine granulocyte colony-stimulating factor receptor construct show that SB-247464 binds to the extracellular domain of the receptor in a zinc ion-dependent manner. Analytical ultracentrifugation studies demonstrate that SB-247464 induces self-association of the N-terminal three-domain fragment in a manner that is consistent with dimerization. SB-247464 induces internalization of granulocyte colony-stimulating factor receptor on intact cells, consistent with a mechanism involving receptor oligomerization. These data show that small nonpeptidyl compounds are capable of selectively binding and inducing productive oligomerization of cytokine receptors.
Subject(s)
Receptors, Granulocyte Colony-Stimulating Factor/chemistry , Receptors, Granulocyte Colony-Stimulating Factor/metabolism , Animals , Benzimidazoles/pharmacology , Bone Marrow Cells/metabolism , Calorimetry , Cell Line , Circular Dichroism , Cytokines/metabolism , Dimerization , Dose-Response Relationship, Drug , Edetic Acid/pharmacology , Guanidines/pharmacology , Ions , Ligands , Mice , Models, Chemical , Peptides/chemistry , Protein Binding , Protein Structure, Tertiary , Recombinant Fusion Proteins/metabolism , Signal Transduction , Transfection , Ultracentrifugation , ZincABSTRACT
The hepatitis C virus (HCV) NS5B protein encodes an RNA-dependent RNA polymerase (RdRp), the primary catalytic enzyme of the HCV replicase complex. We established a biochemical RNA synthesis assay, using purified recombinant NS5B lacking the C-terminal 21 amino acid residues, to identify potential polymerase inhibitors from a high throughput screen of the GlaxoSmithKline proprietary compound collection. The benzo-1,2,4-thiadiazine compound 1 was found to be a potent, highly specific inhibitor of NS5B. This agent interacts directly with the viral polymerase and inhibits RNA synthesis in a manner noncompetitive with respect to GTP. Furthermore, in the absence of an in vitro-reconstituted HCV replicase assay employing viral and host proteins, the ability of compound 1 to inhibit NS5B-directed viral RNA replication was determined using the Huh7 cell-based HCV replicon system. Compound 1 reduced viral RNA in replicon cells with an IC(50) of approximately 0.5 microm, suggesting that the inhibitor was able to access the perinuclear membrane and inhibit the polymerase activity in the context of a replicase complex. Preliminary structure-activity studies on compound 1 led to the identification of a modified inhibitor, compound 4, showing an improvement in both biochemical and cell-based potency. Lastly, data are presented suggesting that these compounds interfere with the formation of negative and positive strand progeny RNA by a similar mode of action. Investigations are ongoing to assess the potential utility of such agents in the treatment of chronic HCV disease.