ABSTRACT
We have identified macrocyclic inhibitors of the aspartic protease BACE, implicated in the etiology of Alzheimer's disease. An X-ray structure of screening hit 1 in the BACE active site revealed a hairpin conformation suggesting that constrained macrocyclic derivatives may also bind there. Several of the analogs we prepared were >100x more potent than 1, such as 7 (5 nM K(i)).
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Macrocyclic Compounds/chemistry , Protease Inhibitors/chemistry , Quinazolines/chemistry , Amyloid Precursor Protein Secretases/metabolism , Aspartic Acid Endopeptidases/metabolism , Binding Sites , Computer Simulation , Humans , Macrocyclic Compounds/chemical synthesis , Macrocyclic Compounds/pharmacology , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Quinazolines/chemical synthesis , Quinazolines/pharmacology , Structure-Activity RelationshipABSTRACT
We have discovered that phenyltriazolinone is a novel and potent P1 moiety for coagulation factor Xa. X-ray structures of the inhibitors with a phenyltriazolinone in the P1 position revealed that the side chain of Asp189 has reoriented resulting in a novel S1 binding pocket which is larger in size to accommodate the phenyltriazolinone P1 substrate.
Subject(s)
Anticoagulants/chemical synthesis , Drug Design , Factor Xa Inhibitors , Isoxazoles/chemical synthesis , Pyrazoles/chemical synthesis , Pyridones/chemical synthesis , Sulfones/chemical synthesis , Anticoagulants/chemistry , Anticoagulants/pharmacology , Crystallography, X-Ray , Humans , Isoxazoles/chemistry , Isoxazoles/pharmacology , Models, Molecular , Molecular Structure , Pyrazoles/chemistry , Pyrazoles/pharmacology , Pyridones/chemistry , Pyridones/pharmacology , Sulfones/chemistry , Sulfones/pharmacologyABSTRACT
Ortho-substituted biphenyl moieties are widely used in drug design. We herein report a successful use of the perpendicular conformation of the alpha-substituted phenylcyclopropyl groups to mimic the aplanar, biologically active conformation of the ortho-substituted biphenyl moieties to achieve structural diversity. This is exemplified by the design and synthesis of a series of highly potent pyrazole bicyclic-based Factor Xa (FXa) inhibitors bearing alpha-substituted phenylcyclopropyl P4 moieties. The designed perpendicular conformation was confirmed by the X-ray structure of FXa-bound compound 2r. The potential structural basis for the high FXa potency in the phenylcyclopropyl P4 analogs and their improved FXa inhibitory activities compared with the biphenyl P4 counterparts are discussed.
Subject(s)
Biphenyl Compounds/chemistry , Cyclopropanes/chemistry , Factor Xa Inhibitors , Factor Xa/chemistry , Binding Sites , Blood Coagulation/drug effects , Cell Line, Tumor , Chemistry, Pharmaceutical/methods , Drug Design , Electrons , Humans , Kinetics , Models, Chemical , Models, Molecular , Molecular Conformation , Thrombosis/drug therapyABSTRACT
Efforts to identify a suitable follow-on compound to razaxaban (compound 4) focused on modification of the carboxamido linker to eliminate potential in vivo hydrolysis to a primary aniline. Cyclization of the carboxamido linker to the novel bicyclic tetrahydropyrazolopyridinone scaffold retained the potent fXa binding activity. Exceptional potency of the series prompted an investigation of the neutral P1 moieties that resulted in the identification of the p-methoxyphenyl P1, which retained factor Xa binding affinity and good oral bioavailability. Further optimization of the C-3 pyrazole position and replacement of the terminal P4 ring with a neutral heterocycle culminated in the discovery of 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide (apixaban, compound 40). Compound 40 exhibits a high degree of fXa potency, selectivity, and efficacy and has an improved pharmacokinetic profile relative to 4.
Subject(s)
Factor Xa Inhibitors , Fibrinolytic Agents/chemical synthesis , Pyrazoles/chemical synthesis , Pyridones/chemical synthesis , Administration, Oral , Animals , Biological Availability , Blood Coagulation/drug effects , Crystallography, X-Ray , Dogs , Fibrinolytic Agents/pharmacokinetics , Fibrinolytic Agents/pharmacology , Humans , In Vitro Techniques , Models, Molecular , Molecular Structure , Pyrazoles/pharmacokinetics , Pyrazoles/pharmacology , Pyridones/pharmacokinetics , Pyridones/pharmacology , Rabbits , Structure-Activity RelationshipABSTRACT
A new aspartic protease inhibitory chemotype bearing a 2-amino-3,4-dihydroquinazoline ring was identified by high-throughput screening for the inhibition of BACE-1. X-ray crystallography revealed that the exocyclic amino group participated in a hydrogen bonding array with the two catalytic aspartic acids of BACE-1 (Asp(32), Asp(228)). BACE-1 inhibitory potency was increased (0.9 microM to 11 nM K(i)) by substitution into the unoccupied S(1)' pocket.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Models, Molecular , Quinazolines/chemical synthesis , Amyloid Precursor Protein Secretases/chemistry , Amyloid beta-Peptides/antagonists & inhibitors , Amyloid beta-Peptides/blood , Amyloid beta-Peptides/metabolism , Amyloid beta-Protein Precursor/genetics , Animals , Aspartic Acid Endopeptidases/chemistry , CHO Cells , Caco-2 Cells , Cell Membrane Permeability , Cricetinae , Cricetulus , Crystallography, X-Ray , Humans , Hydrogen Bonding , Molecular Conformation , Mutation , Oligopeptides/chemistry , Peptide Fragments/antagonists & inhibitors , Peptide Fragments/blood , Peptide Fragments/metabolism , Quinazolines/chemistry , Quinazolines/pharmacology , Rats , Stereoisomerism , Structure-Activity RelationshipABSTRACT
The bicyclic dihydropyrazolopyridinone scaffold allowed for incorporation of multiple P1 moieties with subnanomolar binding affinities for blood coagulation factor Xa. The compound 3-[6-(2'-dimethylaminomethyl-biphenyl-4-yl)-7-oxo-3-trifluoro-methyl-4,5,6,7-tetrahydro-pyrazolo[3,4-c]pyridine-l-yl]-benzamide 6d shows good fXa potency, selectivity, in vivo efficacy and oral bioavailability. Compound 6d was selected for further pre-clinical evaluations.
Subject(s)
Benzamides/chemistry , Benzamides/pharmacology , Factor Xa Inhibitors , Fibrinolytic Agents/chemistry , Fibrinolytic Agents/pharmacology , Administration, Oral , Benzamides/administration & dosage , Benzamides/chemical synthesis , Fibrinolytic Agents/administration & dosage , Fibrinolytic Agents/chemical synthesis , Humans , Treatment OutcomeABSTRACT
Attempts to further optimize the pyrazole factor Xa inhibitors centered on masking the aryl aniline P4 moiety. Scaffold optimization resulted in the identification of a novel bicyclic pyrazolo-pyridinone scaffold which retained fXa potency. The novel bicyclic scaffold preserved all binding interactions observed with the monocyclic counterpart and importantly the carboxamido moiety was integrated within the scaffold making it less susceptible to hydrolysis. These efforts led to the identification of 1-[3-aminobenzisoxazol-5'-yl]-3-trifluoromethyl-6-[2'-(3-(R)-hydroxy-N-pyrrolidinyl)methyl-[1,1']-biphen-4-yl]-1,4,5,6-tetrahydropyrazolo-[3,4-c]-pyridin-7-one 6f (BMS-740808), a highly potent (fXa Ki=30 pM) with a rapid onset of inhibition (2.7x10(7) M-1 s-1) in vitro, selective (>1000-fold over other proteases), efficacious in the AVShunt thrombosis model, and orally bioavailable inhibitor of blood coagulation factor Xa.
Subject(s)
Factor Xa Inhibitors , Pyrazoles/pharmacology , Pyridones/pharmacology , Serine Proteinase Inhibitors/pharmacology , Models, Molecular , Pyrazoles/administration & dosage , Pyrazoles/chemistry , Pyridones/administration & dosage , Pyridones/chemistry , Serine Proteinase Inhibitors/administration & dosage , Serine Proteinase Inhibitors/chemistryABSTRACT
Modification of a series of pyrazole factor Xa inhibitors to incorporate an aminobenzisoxazole as the P(1) ligand resulted in compounds with improved selectivity for factor Xa relative to trypsin and plasma kallikrein. Further optimization of the P(4) moiety led to compounds with enhanced permeability and reduced protein binding. The SAR and pharmacokinetic profile of this series of compounds is described herein. These efforts culminated in 1-(3'-aminobenzisoxazol-5'-yl)-3-trifluoromethyl-N-[2-fluoro-4-[(2'-dimethylaminomethyl)imidazol-1-yl]phenyl]-1H-pyrazole-5-carboxyamide (11d), a potent, selective, and orally bioavailable inhibitor of factor Xa. On the basis of its excellent in vitro potency and selectivity profile, high free fraction in human plasma, good oral bioavailability, and in vivo efficacy in antithrombotic models, the HCl salt of this compound was selected for clinical development as razaxaban (DPC 906, BMS-561389).
Subject(s)
Factor Xa Inhibitors , Fibrinolytic Agents/chemical synthesis , Imidazoles/chemical synthesis , Isoxazoles/chemical synthesis , Pyrazoles/chemical synthesis , Administration, Oral , Animals , Biological Availability , Blood Proteins/metabolism , Caco-2 Cells , Crystallography, X-Ray , Dogs , Fibrinolytic Agents/chemistry , Fibrinolytic Agents/pharmacology , Humans , Imidazoles/chemistry , Imidazoles/pharmacology , Isoxazoles/chemistry , Isoxazoles/pharmacology , Models, Molecular , Permeability , Protein Binding , Pyrazoles/chemistry , Pyrazoles/pharmacology , Rabbits , Structure-Activity Relationship , Thrombosis/prevention & controlABSTRACT
Modifications to the P4 moiety and pyrazole C3 substituent of factor Xa inhibitor SN-429 provided several new compounds, which are 5-10nM inhibitors of factor IXa. An X-ray crystal structure of one example complexed to factor IXa shows that these compounds adopt a similar binding mode to that previously observed with pyrazole inhibitors in the factor Xa active site both with regard to how the inhibitor binds and the position of Tyr99.
Subject(s)
Benzimidazoles/chemical synthesis , Factor IXa/antagonists & inhibitors , Factor IXa/chemistry , Factor Xa Inhibitors , Factor Xa/chemistry , Pyrazoles/chemical synthesis , Benzimidazoles/chemistry , Binding Sites , Crystallography, X-Ray , Humans , Models, Molecular , Molecular Structure , Pyrazoles/chemistry , Structure-Activity RelationshipABSTRACT
Factor Xa, a serine protease, is at the critical juncture between the intrinsic and extrinsic pathways of the coagulation cascade. Inhibition of factor Xa has the potential to provide effective treatment for both venous and arterial thrombosis. We recently described a series of meta-substituted phenylpyrazoles that are highly potent, selective, and orally bioavailable factor Xa inhibitors. In this paper we report our efforts to further optimize the selectivity profile of our factor Xa inhibitors with a series of ortho- and/or para-substituted phenylpyrazole derivatives. The most potent compounds display sub-nanomolar inhibition constants for factor Xa and show greater than 1000-fold selectivity against other serine proteases. These compounds are also effective in a rabbit model of arteriovenous shunt thrombosis. Optimization of this series led to the preclinical development of DPC602, a 2-(aminomethyl)phenylpyrazole analogue, as a highly potent, selective, and orally bioavailable factor Xa inhibitor.
Subject(s)
Factor Xa Inhibitors , Pyrazoles/chemical synthesis , Administration, Oral , Animals , Arteriovenous Shunt, Surgical , Biological Availability , Crystallography, X-Ray , Dogs , Factor Xa/chemistry , Humans , Pyrazoles/pharmacokinetics , Pyrazoles/pharmacology , Rabbits , Structure-Activity Relationship , Thrombosis/prevention & controlABSTRACT
As part of an ongoing effort to prepare orally active factor Xa inhibitors using structure-based drug design techniques and molecular recognition principles, a systematic study has been performed on the pharmacokinetic profile resulting from replacing the benzamidine in the P1 position with less basic benzamidine mimics or neutral residues. It is demonstrated that lowering the pK(a) of the P1 ligand resulted in compounds (3-benzylamine, 15a; 1-aminoisoquinoline, 24a; 3-aminobenzisoxazole, 23a; 3-phenylcarboxamide, 22b; and 4-methoxyphenyl, 22a) with improved pharmacokinetic features mainly as a result of decreased clearance, increased volume of distribution, and enhanced oral absorption. This work resulted in a series of potent and orally bioavailable factor Xa inhibitors that ultimately led to the discovery of SQ311, 24a. SQ311, which utilizes a 1-aminoisoquinoline as the P1 ligand, inhibits factor Xa with a K(i) of 0.33 nM and demonstrates both good in vivo antithrombotic efficacy and oral bioavailability.
Subject(s)
Anticoagulants/chemical synthesis , Anticoagulants/pharmacology , Benzamidines/pharmacology , Factor Xa Inhibitors , Guanidines/pharmacology , Isoquinolines/chemical synthesis , Isoquinolines/pharmacology , Sulfonamides/chemical synthesis , Sulfonamides/pharmacology , Animals , Anticoagulants/pharmacokinetics , Binding Sites/drug effects , Biological Availability , Crystallography, X-Ray , Dogs , Drug Design , Hydrogen Bonding , Indicators and Reagents , Intestinal Absorption , Molecular Mimicry , Rabbits , Structure-Activity Relationship , Thrombin/chemistryABSTRACT
Factor Xa (fXa) is an important serine protease that holds the central position linking the intrinsic and extrinsic activation mechanisms in the blood coagulation cascade. Therefore, inhibition of fXa has potential therapeutic applications in the treatments of both arterial and venous thrombosis. Herein we describe a series of tetrazole fXa inhibitors containing benzamidine mimics as the P(1) substrate, of which the aminobenzisoxazole moiety was found to be the most potent benzamidine mimic. SR374 (12) inhibits fXa with a K(i) value of 0.35 nM and is very selective for fXa over thrombin and trypsin.
