Discovery of a Novel Highly Selective Histamine H4 Receptor Antagonist for the Treatment of Atopic Dermatitis.

The histamine H4 receptor (H4R), a member of the G-protein coupled receptor family, has been considered as a potential therapeutic target for treating atopic dermatitis (AD). A large number of H4R antagonists have been disclosed, but no efficient agents controlling both pruritus and inflammation in AD have been developed yet. Here, we have discovered a novel class of orally available H4R antagonists showing strong anti-itching and anti-inflammation activity as well as excellent selectivity against off-targets. A pharmacophore-based virtual screening system constructed in-house successfully identified initial hit compound 9, and the subsequent homology model-guided optimization efficiently led us to discover pyrido[2,3- e]tetrazolo[1,5- a]pyrazine analogue 48 as a novel chemotype of a potent and highly selective H4R antagonist. Importantly, orally administered compound 48 exhibits remarkable efficacy on antipruritus and anti-inflammation with a favorable pharmacokinetic (PK) profile in several mouse models of AD. Thus, these data strongly suggest that our compound 48 is a promising clinical candidate for treatment of AD.

Acetazolamide-based [18F]-PET tracer: In vivo validation of carbonic anhydrase IX as a sole target for imaging of CA-IX expressing hypoxic solid tumors.

Carbonic anhydrase IX is overexpressed in many solid tumors including hypoxic tumors and is a potential target for cancer therapy and diagnosis. Reported imaging agents targeting CA-IX are successful mostly in clear cell renal carcinoma as SKRC-52 and no candidate was approved yet in clinical trials for imaging of CA-IX. To validate CA-IX as a valid target for imaging of hypoxic tumor, we designed and synthesized novel [18F]-PET tracer (1) based on acetazolamide which is one of the well-known CA-IX inhibitors and performed imaging study in CA-IX expressing hypoxic tumor model as 4T1 and HT-29 in vivo models other than SKRC-52. [18F]-acetazolamide (1) was found to be insufficient for the specific accumulation in CA-IX expressing tumor. This study might be useful to understand in vivo behavior of acetazolamide PET tracer and can contribute to the development of successful PET imaging agents targeting CA-IX in future. Additional study is needed to understand the mechanism of poor targeting of CA-IX, as if CA-IX is not reliable as a sole target for imaging of CA-IX expressing hypoxic solid tumors.

Discovery of 6-benzyloxyquinolines as c-Met selective kinase inhibitors.

A novel quinoline derivative that selectively inhibits c-Met kinase was identified. The molecular design is based on a result of the analysis of a PF-2341066 (1)/c-Met cocrystal structure (PDB code: 2wgj). The kinase selectivity of the derivatives is discussed from the view point of the sequence homology of the kinases, the key interactions found in X-ray cocrystal structures, and the structure-activity relationship (SAR) obtained in this work.

Sacral intraspinal bronchogenic cyst: a case report.

Intraspinal bronchogenic cysts are rare congenital cystic lesions. In all the reported cases, the cysts have been located in the cervical, upper thoracic or thoracolumbar segments. We report the case of an intraspinal bronchogenic cyst in the sacral location. We present the case of a 5-month-old female with a skin dimple in the midline over the sacral vertebra. Magnetic resonance image of the lumbar and sacral vertebra revealed a dermal sinus tract and an epidural cystic mass at the S2 level. The patient underwent the removal of the dermal sinus tract and the cyst. The cystic mass was shown to be connected to the subarachnoid space through a slender pedicle from the dura. The cyst was diagnosed to be a bronchogenic cyst based on the results of the histopathological examination. We conclude that intraspinal bronchogenic cysts may appear in the sacral location.

Quantitative structure-activity relationship of spirosuccinimide type aldose reductase inhibitors diminishing sorbitol accumulation in vivo.

Racemate physicochemical descriptors are employed to probe the quantitative structure-activity relationship of spirosuccinimide type aldose reductase inhibitors and the in vivo inhibitory activity of sorbitol accumulation. The in vivo activity data include the percent inhibition and ED50 assay results on the literature. The derived QSAR equations show that the hydrophobic character of aldose reductase inhibitor is the major contributing factor to enhance in vivo activity. As the hydrophobicity of compounds is related to both the membrane permeability and the binding affinity to the aldose reductase, its contribution to the pharmacokinetic behavior is further scrutinized by evaluating pKa and the Caco-2 cell permeability. The high correlation between ED50 and the Caco-2 cell permeability of in vitro active compounds indicates that the membrane permeability is essential for in vivo efficacy.

The tumor suppressor p16(INK4a) prevents cell transformation through inhibition of c-Jun phosphorylation and AP-1 activity.

Inactivation of the p16(INK4a) tumor suppressor protein is critical for the development of human cancers, including human melanoma. However, the molecular basis of the protein's inhibitory effect on cancer development is not clear. Here we investigated a possible mechanism for p16(INK4a) inhibition of neoplastic transformation and UV-induced skin cancer. We show that p16(INK4a) suppresses the activity of c-Jun N-terminal kinases (JNKs) and that it binds to the glycine-rich loop of the N-terminal domain of JNK3. Although p16(INK4a) does not affect the phosphorylation of JNKs, its interaction with JNK inhibits c-Jun phosphorylation induced by UV exposure. This, in turn, interferes with cell transformation promoted by the H-Ras-JNK-c-Jun-AP-1 signaling axis.

Quantitative structure and aldose reductase inhibitory activity relationship of 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazine-4-spiro-3'-pyrrolidine-1,2',3,5'-tetrone derivatives.

We investigate the quantitative structure-activity relationship of spirosuccinimide-fused tetrahydropyrrolo[1,2-a]pyrazine-1,3-dione derivatives acting as aldose reductase inhibitors, which contain a chiral center. The published assay data of 30 training compounds are not for optically pure enantiomer preparations but for racemic mixtures. As the physicochemical descriptors for the QSAR analysis must be evaluated for either (R)-enantiomer or (S)-enantiomer, we devise a new 'racemic' descriptor as the arithmetic mean of the (R)-enantiomer descriptor and the (S)-enantiomer descriptor. The resultant QSAR model derived from the racemic descriptors outperforms the original QSAR models. The racemic QSAR model shows that the hydrophobic character of the benzyl moiety is the major contributing factor to the aldose reductase inhibitory activity and the polar surface area descriptors modulate the inhibitory activity.

Syntheses of sphingosine-1-phosphate analogues and their interaction with EDG/S1P receptors.

Sphingosine-1-phosphate (S1P) is an important regulator of a wide variety of biological processes acting as an endogenous ligand to EDG/S1P receptors. In an effort to establish structure-activity relationship between EDG/S1P and ligands, we report herein homology modeling study of EDG-1/S1P(1), syntheses of S1P analogues, and cell based binding affinity study for EDG/S1P receptors.