Publications by authors named "Jun Chiba"

Background/aims: Vascular endothelial growth factor (VEGF) is a key molecule in the regulation of both angiogenesis and vascular permeability. However, it is known that overproduction of VEGF induces abnormal blood vessel formation and these vessels cause several disease pathologies, such as diabetic retinopathy. The purpose of this study was to find novel vasoactive compounds which have different properties from VEGF.

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We conducted a screening program for vasoactive compounds and detected a potent activity in the cultured broth of Streptomyces sp. SANK 63697. From the cultured broth, two active compounds, vestaine A and B, were isolated.

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Caramel color is widely used in the food industry, and its many variations are generally considered to be safe. It has been known for a long time that THI (2-acetyl-4-(tetrahydroxybutyl)imidazole), a component of caramel color III, causes lymphopenia in animals through sphingosine 1-phosphate (S1P) lyase (S1PL) inhibition. However, this mechanism of action has not been fully validated because THI does not inhibit S1PL in vitro.

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We have carried out the optimization of substituents at the C-3 or the C-5 position on the pyrrolidine ring of VLA-4 antagonist 3 with 2-(phenylamino)-7-fluorobenzoxazolyl moiety for the purpose of improving in vivo efficacy while maintaining good aqueous solubility. As a result, we successfully increased in vitro activity in the presence of 3% human serum albumin and achieved an exquisite lipophilic and hydrophilic balance of compounds suitable for oral administrative regimen. The modification resulted in the identification of zwitterionic compound 7n with (5S)-[methoxy(methyl)amino]methylpyrrolidine, which significantly alleviated bronchial hyper-responsiveness to acetylcholine chloride at 12.

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This contribution describes a concise synthesis to ethyl trans-[(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylate (2b) as a key intermediate of very late antigen-4 (VLA-4) antagonist trans-4-[1-[[2,5-dichloro-4-(1-methyl-3-indolylcarboxyamide)phenyl]acetyl]-(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylic acid (1). The synthesis employs a reductive etherification as a key reaction using (2S,4S)-1-benzyloxycarbonyl-4-methoxypyrrolidine-2-carboxyaldehyde (12) and trans-4-triethylsilyloxycyclohexanecarboxilic acid ethyl ester (13b). This synthesis provides 2b in 6 steps with 38% overall yield from commercially available starting material.

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For the purpose of obtaining orally potent VLA-4 inhibitors, we have carried out structural modification of the (N'-phenylureido)phenyl group in compound 1, where the group was found to be attributed to poor pharmacokinetic profile in our previous research. Through modification, we have identified several compounds with both potent in vitro activity and improved oral exposure. In particular, compound 7e with 7-fluoro-2-(1-methyl-1H-indol-3-yl)-1,3-benzoxazolyl group as a novel replacement of the (N'-phenylureido)phenyl group significantly inhibited eosinophil infiltration into bronchoalveolar lavage fluid at 15mg/kg in an Ascaris-antigen-induced murine bronchial inflammatory model, and its efficacy was comparable to that of the anti-mouse α(4) antibody (R1-2).

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This contribution describes a novel synthetic approach to very late antigen-4 (VLA-4) antagonist trans-4-[1-[[2,5-dichloro-4-(1-methyl-3-indolylcarboxyamide)phenyl]acetyl]-(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylic acid (1) via tert-butyl trans-[(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylate (2b) as a key intermediate. The synthesis, which includes n-Bu₄NSO₃H that catalyzed basic etherification of 12 and iodine-mediated cyclization to provide the 2,4-disubstituted pyrrolidine frame of 2b, is designed to utilize trans-4-hydroxycyclohexanecarboxylic acid (9) as a commercially available starting material.

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We have focused on optimization of the inadequate pharmacokinetic profile of trans-4-substituted cyclohexanecarboxylic acid 5, which is commonly observed in many small molecule very late antigen-4 (VLA-4) antagonists. We modified the lipophilic moiety in 5 and found that reducing the polar surface area of this moiety results in improvement of the PK profile. Consequently, our efforts have led to the discovery of trans-4-[1-[[2,5-dichloro-4-(1-methyl-3-indolylcarboxamido)phenyl]acetyl]-(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylic acid (14e) with potent activity (IC(50) = 5.

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During the course of our study, it was revealed that the poor pharmacokinetic properties of a series of benzoic acid derivatives such as 1 should be attributed to the diphenylurea moiety. Thus, we replaced the diphenylurea moiety in 1 with a 2-(2-methylphenylamino)benzoxazole moiety which mimics the diphenylurea structure. However, this modification resulted in a significant decrease (3, IC(50)=19 nM) in VLA-4 inhibitory activity compared to 1 (IC(50)=1.

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The synthesis and evaluation of new analogues of thieno[2,3-d]pyrimidin-4-yl hydrazones are described. 2-Pyrdinecarboxaldehyde [6-(tert-butyl)thieno[2,3-d]pyrimidine-4-yl]hydrazone derivatives have been identified as cyclin-dependent kinase 4 (CDK4) inhibitors. The potency, selectivity profile, and structure-activity relationship of this series of compounds are discussed.

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Optimization of benzoic acid derivatives by introducing substituents into the diphenyl urea moiety led to the identification of compound 20l as a potent VLA-4 antagonist. Compound 20l inhibited eosinophil infiltration into bronchial alveolar lavage fluid in a murine asthma model by oral dosing and its efficacy was comparable to anti-mouse alpha4 antibody (R1-2). Furthermore, this compound significantly blocked bronchial hyper-responsiveness in the model.

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A series of benzoic acid derivatives was synthesized as VLA-4 antagonists. Introduction of chlorine or bromine into the 3-position on the central benzene of the diphenylurea portion as in lead compound 2 led to improvement in the pharmacokinetic properties. In particular, 12l demonstrated an acceptable plasma clearance and bioavailability in mice and rats as well as dogs (mice, CL=18.

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A novel series of benzoic acid derivatives as VLA-4 antagonists were synthesized. Optimization, focusing on activity and lipophilicity needed for cell permeability, resulted in the identification of 15b and 15e with good activity (IC50 = 1.6 nM each) and moderate lipophilicity (Log D = 2.

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The isolate from a canine disseminated protothecosis was identified to be Prototheca wickerhamii by its morphological and biochemical characteristics. The isolate was grouped into a cluster identical to the type strain of P. wickerhamii, ATCC 16529(T) in phylogenetic trees based on the small subunit (SSU) and the 5' end of the large subunit (LSU) ribosomal DNA (rDNA); the cluster was close to that including the other Prototheca species.

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The formation reaction and the intercalation of adenosine triphosphate (ATP) were studied for hydrotalcite (HT), a layered double hydroxide (LDH) of magnesium and aluminum. Hydrotalcite with nitrate ions in the interlayer (HT-NO(3)) was formed (A) by dropwise addition of a solution of magnesium and aluminum nitrates (pH ca. 3) to a sodium hydroxide solution (pH ca.

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A series of prolyl-1-piperazinylacetic acid and prolyl-4-piperidinylacetic acid derivatives were synthesized and evaluated for their activity as VLA-4 antagonists. Of 22 compounds synthesized, 19 compounds showed potent activity with low nanomolar IC50 values. In addition, the representative compounds 11o and 11p with a hydroxy group in the pyrrolidine ring showed moderate plasma clearance in rats (11o, 30 ml/min/kg and 11p, 21 ml/min/kg) and in dogs (11o, 12 ml/min/kg and 11p, 9 ml/min/kg).

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An investigation into the structure-activity relationship of a lead compound, prolyl-5-aminopentanoic acid 4, led to the identification of a novel series of 4-piperidinylacetic acid, 1-piperazinylacetic acid, and 4-aminobenzoic acid derivatives as potent VLA-4 antagonists with low nanomolar IC(50) values. A representative compound morpholinyl-4-piperidinylacetic acid derivative (13d: IC(50)=4.4 nM) showed efficacy in the Ascaris-antigen sensitized murine airway inflammation model by oral administration.

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It was shown that a new taxane analogue 3, which exhibited both in vitro antitumor activity and in vivo efficacy by both i.v. and p.

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We synthesized novel water-soluble and orally active taxane analogues, 7-deoxy-9beta-dihydro-9,10-O-acetal taxanes. Cytotoxicities of the synthetic compounds were greater than those of paclitaxel and docetaxel, especially against resistant cancer cell lines expressing P-glycoprotein. In addition, some compounds showed potent antitumor effects against B16 melanoma BL6 in vivo by both iv and po administration.

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Article Synopsis
  • The study focused on understanding how modifications to the 7-hydroxyl groups of certain taxoid compounds affect their activity.
  • Different modifications were tested, including deoxy, methoxy, alpha-fluorine, and a unique methano group.
  • The 7-deoxy analogue was found to be the most potent, with stronger effects against specific cancer cell lines compared to related compounds.
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