Discovery of 7-Oxo-2,4,5,7-tetrahydro-6 H-pyrazolo[3,4- c]pyridine Derivatives as Potent, Orally Available, and Brain-Penetrating Receptor Interacting Protein 1 (RIP1) Kinase Inhibitors: Analysis of Structure-Kinetic Relationships.

We report the discovery of 7-oxo-2,4,5,7-tetrahydro-6 H-pyrazolo[3,4- c]pyridine derivatives as a novel class of receptor interacting protein 1 (RIP1) kinase inhibitors. On the basis of the overlay study between HTS hit 10 and GSK2982772 (6) in RIP1 kinase, we designed and synthesized a novel class of RIP1 kinase inhibitor 11 possessing moderate RIP1 kinase inhibitory activity and P-gp mediated efflux. The optimization of the core structure and the exploration of appropriate substituents utilizing SBDD approach led to the discovery of 22, a highly potent, orally available, and brain-penetrating RIP1 kinase inhibitor with excellent PK profiles. Compound 22 significantly suppressed necroptotic cell death both in mouse and human cells. Oral administration of 22 (10 mg/kg, bid) attenuated disease progression in the mouse experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). Moreover, analysis of structure-kinetic relationship (SKR) for our novel chemical series was also discussed.

Discovery and pharmacological characterization of a new class of prolyl-tRNA synthetase inhibitor for anti-fibrosis therapy.

Scleroderma has clinical characteristics including skin and other tissue fibrosis, but there is an unmet need for anti-fibrotic therapy. Halofuginone (HF) is a well-known anti-fibrosis agent in preclinical and clinical studies which exerts its effect via inhibition of TGF-ß/Smad3 signaling pathway. Recently, prolyl-tRNA synthetase (PRS) was elucidated as a target protein for HF that binds to the proline binding site of the catalytic domain of PRS. Here, we characterized a new class of PRS inhibitor (T-3833261) that is carefully designed in a way that binds to the ATP site of the catalytic domain and does not disrupt binding of proline. The anti-fibrotic activity and the mechanism of action for T-3833261 on TGF-ß-induced fibrotic assay were compared with those of HF in primary human skin fibroblast. We evaluated in vivo effect of topical application of T-3833261 and HF on TGF-ß-induced fibrotic genes expression in mice. We found that T-3833261 suppressed TGF-ß-induced α-smooth muscle actin (α-SMA) and type I collagen α1 (COL1A1) expression through the Smad3 axis in a similar fashion to HF. In vivo topical application of T-3833261 reduced the increase of fibrotic genes expression such as α-Sma, Col1a1 and Col1a2 by TGF-ß intradermal injection to the ear of a mouse. We revealed that T-3833261 is more effective than HF under the conditions of high proline concentration, as reported in fibrotic tissues. These results suggest the potential of ATP competitive PRS inhibitors for the treatment of fibrotic diseases such as scleroderma.

Synthesis and evaluation of hedgehog signaling inhibitor with novel core system.

As we previously reported, N-methylpyrrolo[3,2-c]pyridine derivatives 1 (TAK-441) was discovered as a clinical candidate of hedgehog (Hh) signaling inhibitor by modification of the upper part. We next focused on modification of the lower part including core skeletons to discover new Hh signaling inhibitors with novel core rings. Efforts to find novel chemotypes by using X-ray single crystal structure analysis led to some potent Hh signaling inhibitors (2c, 2d, 2e, 2f) with novel core ring systems, which had benzamide moiety at the 5-position as a key component for potent activity. The suppression of Gli1 expression with these new Hh signaling inhibitors were weaker than that of compound 1 (TAK-441) because of low pharmacokinetic property. We recognized again TAK-441 is a good compound as clinical candidate with good structural and pharmacokinetic advantages.

Discovery of the investigational drug TAK-441, a pyrrolo[3,2-c]pyridine derivative, as a highly potent and orally active hedgehog signaling inhibitor: modification of the core skeleton for improved solubility.

We recently reported the discovery of the novel pyrrolo[3,2-c]quinoline-4-one derivative 1 as a potent inhibitor of Hedgehog (Hh) pathway signaling. However, the PK evaluation of 1 at high dosage (100 mg/kg) revealed the C(max) value 3.63 µg/mL, likely due to poor solubility of this compound. Efforts to improve solubility by reducing the aromatic ring count of the core system led to N-methylpyrrolo[3,2-c]pyridine derivative 11. Further optimization of the 3-alkoxy group led to compound 11d with acceptable solubility and potent Hh inhibitory activity. Compound 11d suppressed transcription factor Gli1 mRNA expression in tumor-associated stromal tissue and inhibited tumor growth (treatment/control ratio, 3%) in a mouse medulloblastoma allograft model owing to the improved PK profile based on increased solubility. Compound 11d (TAK-441) is currently in clinical trials for the treatment of advanced solid tumors.

Discovery of pyrrolo[3,2-c]quinoline-4-one derivatives as novel hedgehog signaling inhibitors.

The Hedgehog (Hh) signaling pathway plays a significant role in the regulation of cell growth and differentiation during embryonic development. Since activation of the Hh signaling pathway is implicated in several types of human cancers, inhibitors of this pathway could be promising anticancer agents. Using high throughput screening, thieno[3,2-c]quinoline-4-one derivative 9a was identified as a compound of interest with potent in vitro activity but poor metabolic stability. Our efforts focused on enhancement of in vitro inhibitory activity and metabolic stability, including core ring conversion and side chain optimization. This led to the discovery of pyrrolo[3,2-c]quinoline-4-one derivative 12b, which has a structure distinct from previously reported Hh signaling inhibitors. Compound 12b suppressed stromal Gli1 mRNA expression in a murine model and demonstrated antitumor activity in a murine medulloblastoma allograft model.

Effect of roasting on properties of the zinc-chelating substance in coffee brews.

ApV is a brownish polymer with zinc-chelating activity in brewed coffee. We investigated in this study the effects of roasting on the zinc-chelating, reducing, and antioxidative activities of ApV from light-, medium-, and dark-roasted coffee. We also discuss the effect on the zinc-chelating activity of adding milk to the brewed coffee. The chelating activities of ApVs were evaluated by the tetramethyl murexide method. As the intensity of roasting increased, the yield of ApV increased, and the brown color and molecular weight of ApV respectively became darker and higher. Increasing the degree of roasting also decreased the zinc-chelating activity of ApV. The reducing activities of ApVs estimated by the indophenol method were stronger than those of ascorbic acid. Both the antioxidative activity estimated by the ABTS assay and the reducing activity of ApV increased with roasting. When milk was added to instant coffee and its ApV was prepared, the zinc-chelating activity of ApV was not changed.

The Formin family protein, formin homolog overexpressed in spleen, interacts with the insulin-responsive aminopeptidase and profilin IIa.

Insulin stimulates translocation of glucose transporter isoform type 4 (GLUT4) and the insulin-responsive aminopeptidase (IRAP) from an intracellular storage pool to the plasma membrane in muscle and fat cells. A role for the cytoskeleton in insulin action has been postulated, and the insulin signaling pathway has been well investigated; however, the molecular mechanism by which GLUT4/IRAP-containing vesicles move from an interior location to the cell surface in response to insulin is incompletely understood. Here, we have screened for IRAP-binding proteins using a yeast two-hybrid system and have found that the C-terminal domain of FHOS (formin homolog overexpressed in spleen) interacts with the N-terminal cytoplasmic domain of IRAP. FHOS is a member of the Formin/Diaphanous family of proteins that is expressed most abundantly in skeletal muscle. In addition, there are two novel types of FHOS transcripts generated by alternative mRNA splicing. FHOS78 has a 78-bp insertion and it is expressed mainly in skeletal muscle where it may be the most abundant isoform in humans. The ubiquitously expressed FHOS24 has a 24-bp insertion encoding an in-frame stop codon that results in a truncated polypeptide. It is known that some formin family proteins interact with the actin-binding profilin proteins. Both FHOS and FHOS78 bound to profilin IIa via their formin homology 1 domains, but neither bound profilin I or IIb. Overexpression of FHOS and FHOS78 resulted in enhanced insulin-stimulated glucose uptake in L6 cells to similar levels. However, overexpression of FHOS24, lacking the IRAP-binding domain, did not affect insulin-stimulated glucose uptake. These findings suggest that FHOS mediates an interaction between GLUT4/IRAP-containing vesicles and the cytoskeleton and may participate in exocytosis and/or retention of this membrane compartment.