Design, synthesis, and pharmacological evaluation of N-(3-carbamoyl-1H-pyrazol-4-yl)-1,3-oxazole-4-carboxamide derivatives as interleukin-1 receptor-associated kinase 4 inhibitors with reduced potential for cytochrome P450 1A2 induction.

Interleukin-1 receptor-associated kinase 4 (IRAK4) is a critical molecule in Toll-like receptor/interleukin-1 receptor signaling and an attractive therapeutic target for a wide range of inflammatory and autoimmune diseases as well as cancers. In our search for novel IRAK4 inhibitors, we conducted structural modification of a thiazolecarboxamide derivative 1, a lead compound derived from high-throughput screening hits, to elucidate structure-activity relationship and improve drug metabolism and pharmacokinetic (DMPK) properties. First, conversion of the thiazole ring of 1 to an oxazole ring along with introduction of a methyl group at the 2-position of the pyridine ring aimed at reducing cytochrome P450 (CYP) inhibition were conducted to afford 16. Next, modification of the alkyl substituent at the 1-position of the pyrazole ring of 16 aimed at improving CYP1A2 induction properties revealed that branched alkyl and analogous substituents such as isobutyl (18) and (oxolan-3-yl)methyl (21), as well as six-membered saturated heterocyclic groups such as oxan-4-yl (2), piperidin-4-yl (24, 25), and dioxothian-4-y (26), are effective for reducing induction potential. Representative compound AS2444697 (2) exhibited potent IRAK4 inhibitory activity with an IC50 value of 20 nM and favorable DMPK properties such as low risk of drug-drug interactions mediated by CYPs as well as excellent metabolic stability and oral bioavailability.

Full-length in meso structure and mechanism of rat kynurenine 3-monooxygenase inhibition.

The structural mechanisms of single-pass transmembrane enzymes remain elusive. Kynurenine 3-monooxygenase (KMO) is a mitochondrial protein involved in the eukaryotic tryptophan catabolic pathway and is linked to various diseases. Here, we report the mammalian full-length structure of KMO in its membrane-embedded form, complexed with compound 3 (identified internally) and compound 4 (identified via DNA-encoded chemical library screening) at 3.0 Å resolution. Despite predictions suggesting that KMO has two transmembrane domains, we show that KMO is actually a single-pass transmembrane protein, with the other transmembrane domain lying laterally along the membrane, where it forms part of the ligand-binding pocket. Further exploration of compound 3 led to identification of the brain-penetrant compound, 5. We show that KMO is dimeric, and that mutations at the dimeric interface abolish its activity. These results will provide insight for the drug discovery of additional blood-brain-barrier molecules, and help illuminate the complex biology behind single-pass transmembrane enzymes.

Identifying the origin of nitrous oxide dissolved in deep ocean by concentration and isotopocule analyses.

Nitrous oxide (N2O) contributes to global warming and stratospheric ozone depletion. Although its major sources are regarded as bacterial or archaeal nitrification and denitrification in soil and water, the origins of ubiquitous marine N2O maximum at depths of 100-800 m and N2O dissolved in deeper seawater have not been identified. We examined N2O production processes in the middle and deep sea by analyzing vertical profiles of N2O concentration and isotopocule ratios, abundance ratios of molecules substituted with rare stable isotopes 15N or 18O to common molecules 14N14N16O, in the Atlantic, Pacific, Indian, and Southern oceans. Isotopocule ratios suggest that the N2O concentration maxima is generated by in situ microbial processes rather than lateral advection or diffusion from biologically active sea areas such as the eastern tropical North Pacific. Major production process is nitrification by ammonia-oxidizing archaea (AOA) in the North Pacific although other processes such as bacterial nitrification/denitrification and nitrifier-denitrification also significantly contribute in the equatorial Pacific, eastern South Pacific, Southern Ocean/southeastern Indian Ocean, and tropical South Atlantic. Concentrations of N2O below 2000 m show significant correlation with the water mass age, which supports an earlier report suggesting production of N2O during deep water circulation. Furthermore, the isotopocule ratios suggest that AOA produce N2O in deep waters. These facts indicate that AOA have a more important role in marine N2O production than bacteria and that change in global deep water circulation could affect concentration and isotopocule ratios of atmospheric N2O in a millennium time scale.

Discovery of tricyclic dipyrrolopyridine derivatives as novel JAK inhibitors.

Janus kinases (JAKs) play a crucial role in cytokine mediated signal transduction. JAK inhibitors have emerged as effective immunomodulative agents for the prevention of transplant rejection. We previously reported that the tricyclic imidazo-pyrrolopyridinone 2 is a potent JAK inhibitor; however, it had poor oral absorption due to low membrane permeability. Here, we report the structural modification of compound 2 into the tricyclic dipyrrolopyridine 18a focusing on reduction of polar surface area (PSA), which exhibits potent in vitro activity, improved membrane permeability and good oral bioavailability. Compound 18a showed efficacy in rat heterotopic cardiac transplants model.

Protic Ruthenium Tris(pyrazol-3-ylmethyl)amine Complexes Featuring a Hydrogen-Bonding Network in the Second Coordination Sphere.

We synthesized ruthenium complexes bearing a tris(pyrazol-3-ylmethyl)amine ligand LH3 and revealed that this tripodal ligand allows predictable accumulation of three proton-delivering NH groups around a coordination site. The Brønsted acidity of the NH groups in LH3 led to the formation of multiple hydrogen bonds with the substrate ligand and deprotonation. The chlorido complex ligated by LH3 catalyzed disproportionation of 1,2-diphenylhydrazine.

Discovery of 3,6-dihydroimidazo[4,5-d]pyrrolo[2,3-b]pyridin-2(1H)-one derivatives as novel JAK inhibitors.

Because Janus kinases (JAKs) play a crucial role in cytokine-mediated signal transduction, JAKs are an attractive target for the treatment of organ transplant rejection and autoimmune diseases such as rheumatoid arthritis (RA). To identify JAK inhibitors, we focused on the 1H-pyrrolo[2,3-b]pyridine derivative 3, which exhibited moderate JAK3 and JAK1 inhibitory activities. Optimization of 3 identified the tricyclic imidazo-pyrrolopyridinone derivative 19, which exhibited potent JAK3 and JAK1 inhibitory activities (IC50=1.1 nM, 1.5 nM, respectively) with favorable metabolic stability.

Prevalence of Corynebacterium ulcerans in dogs in Osaka, Japan.

Diphtheria-like human illness caused by Corynebacterium ulcerans is an emerging threat in developed countries, with incidence sometimes higher than that of diphtheria caused by Corynebacterium diphtheriae. Companion animals are considered a potential source of human infections. In order to determine the prevalence of C. ulcerans among dogs, we performed a screening for the bacterium in 583 dogs in the custody of the Osaka Prefectural government. Forty-four dogs (7.5 %) were positive for the bacterium, although they did not show any clinical symptoms. All bacterial isolates showed resistance or decreased sensitivity to clindamycin, and some showed decreased sensitivity to levofloxacin. Comparative analysis of isolates using PFGE, toxin gene typing and antibiotic sensitivities suggests that transmission between asymptomatic dogs might have occurred.

Synthesis of eudistomin C and E: improved preparation of the indole unit.

An improved synthesis of the indole unit, a key intermediate for eudistomin C, was established utilizing Makosza's indole synthesis. A concise total synthesis of eudistomin E was achieved on the basis of the improved synthesis.