Discovery of a novel tetrahydroimidazo[1,2-a]pyridine-5-carboxylic acid derivative as a potent and selective heparanase-1 inhibitor utilizing an improved synthetic approach.

Heparanase-1 (HPSE1) is an endo-ß-d-glucuronidase that catalyzes degradation of heparan sulfate proteoglycans. Inhibition of HPSE1 appears to be a useful therapeutic target against cancer and proteinuric kidney diseases. We previously reported tetrahydroimidazo[1,2-a]pyridine 2 as a potent HPSE1 inhibitor after optimization of the synthetic reaction. However, synthesis of 2 involves a total of 19 steps, including a cyclization process that accompanies a strong odor due to the use of Lawesson's reagent and an epimerization reaction; furthermore, 2 exhibited insufficient selectivity for HPSE1 over exo-ß-d-glucuronidase (GUSß) and glucocerebrosidase (GBA), which also needed to be addressed. First, the cyclization reaction was optimized to synthesize tetrahydroimidazo[1,2-a]pyridine without using Lawesson's reagent or epimerization, with reference to previous reports. Next, 16 and 17 containing a bulkier substituent at position 6 than the 6-methoxyl group in 2 were designed and synthesized using the improved cyclization conditions, so that the synthetic route of 16 and 17 was shortened by five steps as compared with that of 2. The inhibitory activities of 16 and 17 against GUSß and GBA were reduced as compared with those of 2, that is, the compounds showed improved selectivity for HPSE1 over GUSß and GBA. In addition, 16 showed enhanced inhibitory activity against HPSE1 as compared with that of 2. Compound 16 appears promising as an HPSE1 inhibitor with therapeutic potential due to its highly potent inhibitory activity against HPSE1 with high selectivity for HPSE1.

Structure-based lead optimization to improve potency and selectivity of a novel tetrahydroimidazo[1,2-a]pyridine-5-carboxylic acid series of heparanase-1 inhibitor.

Heparanase-1 (HPSE1) is an endo-ß-d-glucuronidase that is the only mammalian enzyme known to cleave heparan sulfate (HS) of heparan sulfate proteoglycans (HSPG), a key component of the glycocalyx layer of the vascular endothelium matrix. Inhibition of HPSE1 has therapeutic potential for cancer and proteinuric kidney diseases. We previously reported that 2 showed a moderate potency as an HPSE1 inhibitor and an issue of selectivity against exo-ß-d-glucuronidase (GUSß) and glucocerebrosidase (GBA) remained. A structure-based lead optimization of 2 using X-ray co-crystal structure analysis and fragment molecular orbital calculation resulted in 4e, which showed a more than 7-fold increase in HPSE1 inhibitory activity. The subsequent introduction of a methyl group into the 6-hydroxy group of 4e resulted in 18 with reduced inhibitory activities against GUSß and GBA while maintaining the inhibitory activity against HPSE1. The inhibitory activities of 18 against serum HPSE1 in mice were significant and lasted for 4 h at doses of 3, 30, and 100 mg/kg. Compound 18 could be a novel lead compound for HPSE1 inhibitors with improved inhibitory activity against HPSE1 and increased HPSE1 selectivity over GUSß and GBA.

Lead generation from N-[benzyl(4-phenylbutyl)carbamoyl]amino acid as a novel LPA1 antagonist for the treatment of systemic sclerosis.

Lysophosphatidic acid (LPA), a bioactive phospholipid, binds to the G protein-coupled LPA1 receptor on the surfaces of immune cells, to promote progression of fibrosis of the skin and organs through inducing infiltration of immune cells into tissues, chemokine production, inflammatory cytokine production, and fibroblast transformation. Anti-fibrotic effects of LPA1 blockade have been reported in animal models of scleroderma and scleroderma patients. In the study reported herein, we identified the novel urea compound 5 as a hit compound with LPA1 antagonist activity from our in-house library and synthesized the lead compound TP0541640 (18) by structural transformation utilizing a structure-based drug design (SBDD) approach. Compound 18 possessed potent in vitro LPA1 antagonist activity and exhibited a dose-dependent inhibitory effect against LPA-induced histamine release in mice. Furthermore, 18 significantly suppressed collagen production and skin thickening in a mouse model of bleomycin-induced skin fibrosis. Herein, we describe the compound design strategies and in vivo studies in greater detail.

Discovery of TP0597850: A Selective, Chemically Stable, and Slow Tight-Binding Matrix Metalloproteinase-2 Inhibitor with a Phenylbenzamide-Pentapeptide Hybrid Scaffold.

Matrix metalloproteinase-2 (MMP2) is a zinc-dependent endopeptidase and a promising target for various diseases, including cancer and fibrosis. Herein, we report the discovery of a novel MMP2-selective inhibitor with high chemical stability and slow tight-binding features. Based on the degradation mechanism of our small-molecule-peptide hybrid 1, the tripeptide linker {5-aminopentanoic acid [Ape(5)]-Glu-Asp} of 1 was replaced by a shorter linker (γ-D-Glu). Phenylbenzamide was suitable for the new generation of MMP2 inhibitors as an S1' pocket-binding group. The introduction of (4S)-aminoproline dramatically increased the chemical stability while maintaining high subtype selectivity because of its interaction with Glu130. TP0597850 (18) exhibited high stability over a wide range of pH values as well as potent MMP2 inhibition (Ki = 0.034 nM) and ≥2000-fold selectivity determined using the inhibition constants. A kinetic analysis revealed that it possesses slow tight-binding nature with a long MMP2 dissociative half-life (t1/2 = 265 min).

Lead identification of novel tetrahydroimidazo[1,2-a]pyridine-5-carboxylic acid derivative as a potent heparanase-1 inhibitor.

Heparanase-1 (HPSE1) is an endo-ß-d-glucuronidase that cleaves heparan sulfate proteoglycans into short-chain heparan sulfates (HS). The inhibition of HPSE1 has therapeutic potential for proteinuric diseases such as nephrotic syndrome because increased HPSE1 expression is associated with the loss of HS in the glomerular basement membrane, leading to the development of proteinuria. The present study examined the generation of a lead compound focusing on chemical structures with a sugar moiety, such as glycosides and sugar analogs, taking their physical properties into consideration. Compound 10, an exo-ß-d-glucuronidase (GUSß) inhibitor, was found to have a weak inhibitory activity against endo-ß-d-glucuronidase HPSE1. A structure-activity relationship study using the X-ray co-crystal structure of 10 and HPSE1 resulted in 12a, which showed a more than 14-fold increase in HPSE1 inhibitory activity compared with that of 10. Compound 12a could be a novel lead compound for the development of a potent HPSE1 inhibitor.

Discovery of Novel Pyrazolylpyridine Derivatives for 20-Hydroxyeicosatetraenoic Acid Synthase Inhibitors with Selective CYP4A11/4F2 Inhibition.

20-Hydroxyeicosatetraenoic acid (20-HETE) is one of the major oxidized arachidonic acid (AA) metabolites produced by cytochrome P450 (CYP) 4A11 and CYP4F2 isozymes in the human liver and kidney. Numerous studies have suggested the involvement of 20-HETE in the pathogenesis of renal diseases, and suppression of 20-HETE production by inhibition of CYP4A11 and CYP4F2 may be an attractive therapeutic strategy for renal diseases. At first, we identified methylthiazole derivative 2 as a potent dual inhibitor of CYP4A11 and CYP4F2. An optimization study of a series of derivatives with a molecular weight of around 300 to improve aqueous solubility and selectivity against drug-metabolizing CYPs while maintaining the CYP4A11- and CYP4F2-inhibitory activities led to the identification of acetylpiperidine compound 11c. Compound 11c inhibited 20-HETE production in both human and rat renal microsomes and exhibited a favorable pharmacokinetic profile. Furthermore, 11c also significantly inhibited renal 20-HETE production in Sprague-Dawley rats after oral dosing at 0.1 mg/kg.

Discovery of Aryloxyphenyl-Heptapeptide Hybrids as Potent and Selective Matrix Metalloproteinase-2 Inhibitors for the Treatment of Idiopathic Pulmonary Fibrosis.

Matrix metalloproteinase-2 (MMP2) is a zinc-dependent endopeptidase that plays important roles in the degradation of extracellular matrix proteins. MMP2 is considered to be an attractive target for the treatment of various diseases such as cancer, arthritis, and fibrosis. In this study, we have developed a novel class of MMP2-selective inhibitors by hybridizing the peptide that binds to a zinc ion and S2-S5 pockets with small molecules that bind to the S1' pocket. Structural modifications based on X-ray crystallography revealed that the introduction of 2,4-diaminobutanoic acid (Dab) at position 4 dramatically enhanced MMP2 selectivity by forming an electrostatic interaction with Glu130. After improving the metabolic and chemical stability, TP0556351 (9) was identified. It exhibited potent MMP2 inhibitory activity (IC50 = 0.20 nM) and extremely high selectivity. It suppressed the accumulation of collagen in a bleomycin-induced idiopathic pulmonary fibrosis model in mice, demonstrating the efficacy of MMP2-selective inhibitors for fibrosis.

Design, synthesis and biological evaluation of novel indole derivatives as gut-selective NaPi2b inhibitors.

Intestinal sodium-dependent phosphate transport protein 2b (SLC34A2, NaPi2b) inhibitors are expected to be potential new candidates for anti-hyperphosphatemia drugs. However, a risk of on-target side effects based on the inhibition of NaPi2b in the lung and testis has been reported.In this article, we report on our identification of novel indole derivatives as gut-selective NaPi2b inhibitors with good activity, low systemic exposure and moderate hydrophobicity.In particular, gut-selective compound 27, with even lower bioavailability and lower systemic exposure as compared to previously reported pyridine derivatives, demonstrated excellent phosphate absorption-inhibitory effect in SD rats. Compound 27 has an ideal profile and appears to offer promise as a candidate drug for the treatment of hyperphosphatemia, with minimal risk of side effects due to systemic exposure.

Design, synthesis and biological evaluation of novel pyridine derivatives as gut-selective NaPi2b inhibitors.

We previously reported thiophene derivatives as gut-selective (minimally systemic) and potent sodium-dependent phosphate transport protein 2b (SLC34A2, NaPi2b) inhibitors. However, these derivatives did not suppress phosphate absorption form the intestinal tract in Sprague-Dawley (SD) rats. The lack of efficacy in vivo could be due to the high hydrophobicity of these compounds. In this report, we identified novel pyridine derivatives as gut-selective NaPi2b inhibitors with good activity in vitro and relatively low hydrophobicity. Especially, gut-selective compound 20b suppressed phosphate absorption in SD rats. These results suggest that physical properties, such as the hydrophobicity of the compounds, might affect the in vivo efficacy.

Design, synthesis and biological evaluation of novel 1H-pyrazole-4-carbonyl-4,5,6,7-tetrahydrobenzo [b]thiophene derivatives as gut-selective NaPi2b inhibitors.

Intestinal sodium-dependent phosphate transport protein 2b (SLC34A2, NaPi2b) inhibitors are expected to be potential new candidates for anti-hyperphosphatemia drugs. However, a risk of on-target side effects based on the inhibition of NaPi2b in the lung and testis has been reported. To identify gut-selective (minimally systemic) NaPi2b inhibitors, we prepared and evaluated 1H-pyrazole-4-carbonyl-4,5,6,7-tetrahydrobenzo[b]thiophene derivatives with highly polar functional groups to reduce systemic exposure. As a result, compounds 36a and 36b showed a good activity in vitro and a low bioavailability in Sprague-Dawley (SD) rats. However, these compounds did not suppress phosphate absorption in SD rats. This lack of in vivo efficacy could be due to the high hydrophobicity of these compounds. The results of further investigations of other classes of compounds with appropriate physical properties will be reported in due course.

Synthesis and Structure-Activity Relationship of C-Phenyl D-Glucitol (TP0454614) Derivatives as Selective Sodium-Dependent Glucose Cotransporter 1 (SGLT1) Inhibitors.

Sodium-glucose cotransporter 1 (SGLT1) is the primary transporter for glucose absorption from the gastrointestinal tract. While C-phenyl D-glucitol derivative SGL5213 has been reported to be a potent intestinal SGLT1 inhibitor for use in the treatment of type 2 diabetes, no SGLT1 selectivity was found in vitro (IC50 29 nM for hSGLT1 and 20 nM for hSGLT2). In this study we found a new method of synthesizing key intermediates 12 by a one-pot three-component condensation reaction and discovered C-phenyl D-glucitol 41j (TP0454614), which has >40-fold SGLT1 selectivity in vitro (IC50 26 nM for hSGLT1 and 1101 nM for hSGLT2). The results of our study have provided new insights into the structure-activity relationships (SARs) of the SGLT1 selectivity of C-glucitol derivatives.

Discovery of potent, low-absorbable sodium-dependent glucose cotransporter 1 (SGLT1) inhibitor SGL5213 for type 2 diabetes treatment.

A new series of C-phenyl d-glucitol derivatives was designed and synthesized, and their SGLT1 inhibitory potency and absorbability were evaluated. We also investigated whether kidney drug retention could be avoided by creating molecules with different excretion pathways. To achieve a class of molecules with low absorption and that were excreted in bile, optimized synthesis was performed to bring the ClogP value and the topological polar surface area to within the appropriate ranges. Compounds 34d and 34j were poorly absorbed, but the absorbed compounds were mainly excreted in bile. Thus, smaller amounts of persistent residue in the kidneys were observed. Since 34d exerted a glucose-lowering effect at a dose of 0.3 mg/kg (p.o.) in SD rats, this compound (SGL5213) could be a clinical candidate for the treatment of type 2 diabetes.

Discovery of a potent, low-absorbable sodium-dependent glucose cotransporter 1 (SGLT1) inhibitor (TP0438836) for the treatment of type 2 diabetes.

The design and synthesis of a novel class of low-absorbable SGLT1 inhibitors are described. To achieve low absorption in the new series, we performed an optimization study based on a strategy to increase TPSA. Fortunately, the optimization of an aglycon moiety and a side chain of the distal aglycon moiety led to the identification of compound 30b as a potent and low-absorbable SGLT1 inhibitor. Compound 30b showed a desirable PK profile in Sprague-Dawley (SD) rats and a favorable glucose-lowering effect in diabetic rats.

Discovery of novel 2-[(4-hydroxy-6-oxo-2,3-dihydro-1H-pyridine-5-carbonyl)amino]acetic acid derivatives as HIF prolyl hydroxylase inhibitors for treatment of renal anemia.

Prolyl hydroxylase domain-containing protein (PHD) inhibitors are useful as orally administered agents for the treatment of renal anemia. Based on the common structures of known PHD inhibitors, we found novel PHD inhibitor 1 with a 2-[(4-hydroxy-6-oxo-2,3-dihydro-1H-pyridine-5-carbonyl)amino]acetic acid motif. The PHD2-inhibitory activity, lipophilicity (CLogP), and PK profiles (hepatocyte metabolism, protein binding, and/or elimination half-life) of this inhibitor were used as the evaluation index to optimize the structure and eventually discovered clinical candidate 42 as the suitable compound. Compound 42 was demonstrated to promote the production of erythropoietin (EPO) following oral administration in mice and rats. The predicted half-life of this compound in humans was 1.3-5.6 h, therefore, this drug may be expected to administer once daily with few adverse effects caused by excessive EPO production.

Design, synthesis and biological evaluation of novel 7-azaspiro[3.5]nonane derivatives as GPR119 agonists.

The design and synthesis of a novel class of 7-azaspiro[3.5]nonane GPR119 agonists are described. In this series, optimization of the right piperidine N-capping group (R2) and the left aryl group (R3) led to the identification of compound 54g as a potent GPR119 agonist. Compound 54g showed a desirable PK profile in Sprague-Dawley (SD) rats and a favorable glucose lowering effect in diabetic rats.

Novel 3H-[1,2,3]triazolo[4,5-c]pyridine derivatives as GPR119 agonists: Synthesis and structure-activity/solubility relationships.

We previously reported a novel series of 1H-pyrazolo[3,4-c]pyridine derivatives and the identification of compound 4b as a highly potent GPR119 agonist. However, the advancement of preclinical evaluations of compound 4b is expected to be difficult because of the compound's significantly poor aqueous solubility (0.71µM at pH6.8). In this article, we describe the further optimization of compound 4b focusing on the improvement of its aqueous solubility. Optimization of the central spacer, left-hand aryl group and right-hand piperidine N-capping group led to the identification of a potent GPR119 agonist, 3H-[1,2,3]triazolo[4,5-c]pyridine derivative 32o, with improved solubility (15.9µM at pH6.8).

Design and synthesis of 1H-pyrazolo[3,4-c]pyridine derivatives as a novel structural class of potent GPR119 agonists.

Design and synthesis of a novel class of 1H-pyrazolo[3,4-c]pyridine GPR119 receptor agonists are described. Lead compound 4 was identified through the ligand-based drug design approach. Modification of the left-hand aryl group (R(1)) and right-hand piperidine N-capping group (R(2)) led to the identification of compound 24 as a single-digit nanomolar GPR119 agonist.

(1S)-1,5-anhydro-1-[5-(4-ethoxybenzyl)-2-methoxy-4-methylphenyl]-1-thio-D-glucitol (TS-071) is a potent, selective sodium-dependent glucose cotransporter 2 (SGLT2) inhibitor for type 2 diabetes treatment.

Derivatives of a novel scaffold, C-phenyl 1-thio-D-glucitol, were prepared and evaluated for sodium-dependent glucose cotransporter (SGLT) 2 and SGLT1 inhibition activities. Optimization of substituents on the aromatic rings afforded five compounds with potent and selective SGLT2 inhibition activities. The compounds were evaluated for in vitro human metabolic stability, human serum protein binding (SPB), and Caco-2 permeability. Of them, (1S)-1,5-anhydro-1-[5-(4-ethoxybenzyl)-2-methoxy-4-methylphenyl]-1-thio-D-glucitol (3p) exhibited potent SGLT2 inhibition activity (IC(50) = 2.26 nM), with 1650-fold selectivity over SGLT1. Compound 3p showed good metabolic stability toward cryo-preserved human hepatic clearance, lower SPB, and moderate Caco-2 permeability. Since 3p should have acceptable human pharmacokinetics (PK) properties, it could be a clinical candidate for treating type 2 diabetes. We observed that compound 3p exhibits a blood glucose lowering effect, excellent urinary glucose excretion properties, and promising PK profiles in animals. Phase II clinical trials of 3p (TS-071) are currently ongoing.

An anatomical basis for blocking of the deep cervical plexus and cervical sympathetic tract using an ultrasound-guided technique.

BACKGROUND: A selective blocking method for the cervical plexus and the cervical sympathetic trunk has not yet been established. METHODS: We performed a detailed examination of the neck anatomy using 28 cadavers. The pattern of local anesthetic distribution after injection in 2 healthy volunteers was imaged using computed tomographic scan. RESULTS: The deep cervical plexus was located in the groove between the longus capitis and scalenus medius muscles. The cervical sympathetic trunk was located on the anteromedial surface of the longus capitis. Although anesthetic injected into the longus capitis was confined to the muscle, it infiltrated into neighboring structures including the C2 to C5 roots and sympathetic trunk. CONCLUSIONS: The longus capitis muscle is a suitable landmark for blocking the cervical plexus and trunk.

CW transillumination imaging by extracting weakly scattered light from strongly diffused light.

Transmitted light through a diffuse scattering medium includes strongly diffused light (SDL) and weakly scattered light (WSL). To realize clear transillumination imaging through thick body tissue, which is typically more than 10 mm, we developed a technique to extract the WSL component from diffused light. In experiments using a 15-mm-thick scattering medium (mu(s)' = 1.0/mm), the cross-section of the light propagation area at the center of the medium was confined to a 50% area. This method's usefulness was demonstrated by transillumination imaging through a 40-mm-thick piece of chicken meat. The possibility of depth evaluation was also verified.