ABSTRACT
The design and synthesis of indazolinone containing kinase inhibitors are reported. Regioisomers that showed profound potency variation in previously-reported isoindolinone and aminoindazole systems were surprisingly found to have similar potencies in the case of the indazolinone chemical series. An interpretation using differential hinge hydrogen bonding and tautomeric equilibrium of indazolinone ring system is supported by quantum mechanics calculations. The equipotent inhibition of a representative kinase (KDR) by regioisomeric indazolinones 4 and 5 is clear evidence that in case of the indazolinone hinge, both tautomers are equally favored, and should be considered in design of inhibitors.
Subject(s)
Indazoles/chemical synthesis , Protein Kinase Inhibitors/chemical synthesis , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Indazoles/pharmacology , Isomerism , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
A series of benzoisoxazoles and benzoisothiazoles have been synthesized and evaluated as inhibitors of receptor tyrosine kinases (RTKs). Structure-activity relationship studies led to the identification of 3-amino benzo[ d]isoxazoles, incorporating a N, N'-diphenyl urea moiety at the 4-position that potently inhibited both the vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor families of RTKs. Within this series, orally bioavailable compounds possessing promising pharmacokinetic profiles were identified, and a number of compounds demonstrated in vivo efficacy in models of VEGF-stimulated vascular permeability and tumor growth. In particular, compound 50 exhibited an ED 50 of 2.0 mg/kg in the VEGF-stimulated uterine edema model and 81% inhibition in the human fibrosarcoma (HT1080) tumor growth model when given orally at a dose of 10 mg/kg/day.
Subject(s)
Isoxazoles/chemical synthesis , Models, Molecular , Oxazoles/chemical synthesis , Phenylurea Compounds/chemical synthesis , Receptors, Platelet-Derived Growth Factor/antagonists & inhibitors , Receptors, Vascular Endothelial Growth Factor/antagonists & inhibitors , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/pharmacology , Binding Sites , Biological Availability , Capillary Permeability/drug effects , Cell Line , Cell Line, Tumor , Edema/drug therapy , Female , Humans , Isoxazoles/pharmacokinetics , Isoxazoles/pharmacology , Mice , Mice, Inbred BALB C , NIH 3T3 Cells , Oxazoles/pharmacokinetics , Oxazoles/pharmacology , Phenylurea Compounds/pharmacokinetics , Phenylurea Compounds/pharmacology , Phosphorylation , Structure-Activity Relationship , Uterus/blood supply , Xenograft Model Antitumor AssaysABSTRACT
One of the primary objectives in the design of protein inhibitors is to shape the three-dimensional structures of small molecules to be complementary to the binding site of a target protein. In the course of our efforts to discover potent inhibitors of Bcl-2 family proteins, we found a unique folded conformation adopted by tethered aromatic groups in the ligand that significantly enhanced binding affinity to Bcl-XL. This finding led us to design compounds that were biased by nonbonding interactions present in a urea tether to adopt this bioactive, folded motif. To characterize the key interactions that induce the desired conformational bias, a series of substituted N,N'-diarylureas were prepared and analyzed using X-ray crystallography and quantum mechanical calculations. Stabilizing pi-stacking interactions and destabilizing steric interactions were predicted to work in concert in two of the substitution patterns to promote the bioactive conformation as a global energy minimum and result in a high target binding affinity. Conversely, intramolecular hydrogen bonding present in the third substitution motif promotes a less active, extended conformer as the energetically favored geometry. These findings were corroborated when the inhibition constant of binding to Bcl-XL was determined for fully elaborated analogues bearing these structural motifs. Finally, we obtained the NMR solution structure of the disubstituted N,N'-diarylurea bound to Bcl-XL demonstrating the folded conformation of the urea motif engaged in extensive pi-interactions with the protein.
Subject(s)
Drug Design , bcl-X Protein/antagonists & inhibitors , Binding Sites , Computer Simulation , Crystallography, X-Ray , Ligands , Magnetic Resonance Spectroscopy , Models, Molecular , Protein Structure, Tertiary , bcl-X Protein/chemistry , bcl-X Protein/metabolismABSTRACT
Novel transient receptor potential vanilloid 1 (TRPV1) receptor antagonists with various bicyclic heteroaromatic pharmacophores were synthesized, and their in vitro activity in blocking capsaicin activation of TRPV1 was assessed. On the basis of the contribution of these pharmacophores to the in vitro potency, they were ranked in the order of 5-isoquinoline > 8-quinoline = 8-quinazoline > 8-isoquinoline > or = cinnoline approximately phthalazine approximately quinoxaline approximately 5-quinoline. The 5-isoquinoline-containing compound 14a (hTRPV1 IC50 = 4 nM) exhibited 46% oral bioavailability and in vivo activity in animal models of visceral and inflammatory pain. Pharmacokinetic and pharmacological properties of 14a are substantial improvements over the profile of the high-throughput screening hit 1 (hTRPV1 IC50 = 22 nM), which was not efficacious in animal pain models and was not orally bioavailable.
Subject(s)
Analgesics/chemical synthesis , Isoquinolines/chemical synthesis , Pain/drug therapy , Receptors, Drug/antagonists & inhibitors , Urea/analogs & derivatives , Urea/chemical synthesis , Abdominal Pain/drug therapy , Administration, Oral , Analgesics/chemistry , Analgesics/pharmacology , Animals , Biological Availability , Calcium/metabolism , Cells, Cultured , Disease Models, Animal , Heterocyclic Compounds, 2-Ring/chemical synthesis , Heterocyclic Compounds, 2-Ring/chemistry , Heterocyclic Compounds, 2-Ring/pharmacology , Humans , Hyperalgesia/drug therapy , Isoquinolines/chemistry , Isoquinolines/pharmacology , Models, Molecular , Quinazolines/chemical synthesis , Quinazolines/chemistry , Quinazolines/pharmacology , Quinolines/chemical synthesis , Quinolines/chemistry , Quinolines/pharmacology , Rats , Static Electricity , Structure-Activity Relationship , Urea/chemistry , Urea/pharmacologyABSTRACT
[reaction: see text]. A highly diastereoselective coupling reaction between TBSOP (3) and trityl sulfenimine 4 was developed which provided influenza neuraminidase inhibitor intermediate 7 in 80% yield and >99% de after crystallization. The reaction was shown to be reversible with the high diastereoselectivity resulting from a favorable H-bonding interaction in the major diastereomer.