Discovery of a novel series of medium-sized cyclic enteropeptidase inhibitors.

Enteropeptidase is located in the duodenum that involved in intestinal protein digestion. We have reported enteropeptidase inhibitors with low systemic exposure. The aim of this study was to discover novel enteropeptidase inhibitors showing more potent in vivo efficacy while retaining low systemic exposure.

Novel Pure αVβ3 Integrin Antagonists That Do Not Induce Receptor Extension, Prime the Receptor, or Enhance Angiogenesis at Low Concentrations.

The integrin αVβ3 receptor has been implicated in several important diseases, but no antagonists are approved for human therapy. One possible limitation of current small-molecule antagonists is their ability to induce a major conformational change in the receptor that induces it to adopt a high-affinity ligand-binding state. In response, we used structural inferences from a pure peptide antagonist to design the small-molecule pure antagonists TDI-4161 and TDI-3761.

Discovery of 1,8-naphthyridin-2-one derivative as a potent and selective sphingomyelin synthase 2 inhibitor.

Sphingomyelin synthase 2 (SMS2) has attracted attention as a drug target for the treatment of various cardiovascular and metabolic diseases. The modification of a high throughput screening hit, 2-quinolone 10, enhanced SMS2 inhibition at nanomolar concentrations with good selectivity against SMS1. To improve the pharmaceutical properties such as passive membrane permeability and aqueous solubility, adjustment of lipophilicity was attempted and 1,8-naphthyridin-2-one 37 was identified as a potent and selective SMS2 inhibitor.

Design and synthesis of 1-(1-benzothiophen-7-yl)-1H-pyrazole, a novel series of G protein-coupled receptor 52 (GPR52) agonists.

G-protein-coupled receptor 52 (GPR52) is classified as an orphan Gs-coupled G-protein-coupled receptor. GPR52 cancels dopamine D2 receptor signaling and activates dopamine D1/N-methyl-d-aspartate receptors via intracellular cAMP accumulation. Therefore, GPR52 agonists are expected to alleviate symptoms of psychotic disorders.

Discovery of novel somatostatin receptor subtype 5 (SSTR5) antagonists: Pharmacological studies and design to improve pharmacokinetic profiles and human Ether-a-go-go-related gene (hERG) inhibition.

Somatostatin (SST) is a peptide hormone comprising 14 or 28 amino acids that inhibits endocrine and exocrine secretion via five distinct G-protein-coupled receptors (SSTR1-5). SSTR5 has an important role in inhibiting the secretion of pancreatic and gastrointestinal hormones (e.g.

Discovery and characterization of selective human sphingomyelin synthase 2 inhibitors.

Sphingomyelin synthase (SMS) is a membrane enzyme that catalyzes the synthesis of sphingomyelin, is required for the maintenance of plasma membrane microdomain fluidity, and has two isoforms: SMS1 and SMS2. Although these isoforms exhibit the same SMS activity, they are different enzymes with distinguishable subcellular localizations. It was reported that SMS2 KO mice displayed lower inflammatory responses and anti-atherosclerotic effects, suggesting that inhibition of SMS2 would be a potential therapeutic approach for controlling inflammatory responses and atherosclerosis.

Design, synthesis, and pharmacological evaluation of 4-azolyl-benzamide derivatives as novel GPR52 agonists.

G protein-coupled receptor 52 (GPR52) agonists are expected to improve the symptoms of psychiatric disorders. During exploration for a novel class of GPR52 agonists with good pharmacokinetic profiles, we synthesized 4-(3-(3-fluoro-5-(trifluoromethyl)benzyl)-5-methyl-1H-1,2,4-triazol-1-yl)-2-methylbenzamide (4u; half maximal effective concentration (EC)=75nM, maximal response (E)=122%) starting from a high-throughput screening hit 3 (EC=470nM, E=56%). The structural features of a reported GPR52 agonist were applied to 3, led to design 4-azolylbenzamides as novel GPR52 agonists.

Enantioselective total synthesis of isishippuric acid B via intramolecular Michael reaction.

The first enantioselective total synthesis of isishippuric acid B bearing a novel 4,5-seco-6-norquadrane skeleton was accomplished from (R)-citronellal with use of a Diels-Alder cycloaddition and an intramolecular Michael addition as the ring-forming steps. Comparison of the optical rotation of the synthetic material with that of the natural product confirmed the absolute configuration of isishippuric acid B to be 1R, 2R, 8R, and 11R.

Total synthesis of pteridic acids A and B.

Pteridic acid A (1) is a spirocyclic octaketide produced by the phytoepiphytic actinomycete Streptomyces hygroscopicus TP-A0451 and possesses potent plant-growth-promoting activity comparable to that of indole-3-acetic acid. The enantioselective total synthesis of this natural product was achieved by employing the Sn(OTf)(2)-mediated Evans aldol reaction and the Fukuyama acetylenic coupling reaction as the key C--C bond-forming steps producing 1 through a 14-step sequence in 22 % overall yield from a known oxazolidinone derivative. MgBr(2)-mediated equilibration of an anomerically favored spirocyclic intermediate used for the synthesis of 1 brought about partial epimerization of the spirocenter to give the corresponding anomerically disfavored epimer, which was converted into pteridic acid B (11-epi-1), another plant-growth promoter of the same microbial origin.

Enantioselective total synthesis of pteridic acid A.

Pteridic acid A, a potent plant growth promoter with auxin-like activity, was synthesized enantioselectively by using the Evans asymmetric aldol reaction as the key C-C bond forming step.

Synthesis of the sex pheromone of the citrus mealybug, Pseudococcus cryptus.

The sex pheromone of the citrus mealybug (Pseudococcus cryptus), [(1R,3R)-3-isopropenyl-2,2-dimethylcyclobutyl]methyl 3-methyl-3-butenoate, was synthesized from (+)-alpha-pinene in five operational steps in a 43% overall yield. The synthetic pheromone was identical with the natural pheromone in (1)H-NMR and mass spectroscopic properties, and showed almost the same pheromonal activity as the natural pheromone.

Identification of a sex pheromone component of Pseudococcus cryptus.

A sex pheromone component of Pseudococcus cryptus has been isolated and identified. The crude pheromone extract obtained by airborne collection was fractionated by liquid chromatography (LC) on Florisil, and further purified by high performance liquid chromatography and preparative Gas Chromatography (GC). The pheromone component was shown to be an ester, the alcohol part of which was identical to the known alcohol moiety of the pheromone of Planococcus citri.