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Biomedical subjects

K Isshiki

Publications and source records attributed to K Isshiki.

81 records · Page 5Linked to original sources
PubMed1985

Vanoxonin, a new inhibitor of thymidylate synthetase. II. Structure determination and total synthesis.

Acid hydrolysis of vanoxonin yielded one mol each of 2,3-dihydroxybenzoic acid, L-threonine, L-N omega-hydroxyornithine. Presence of acetyl group in vanoxonin was suggested by the 1H NMR. Periodate oxidation of vanoxonin liberated one mol of acetic acid suggesting that the acetyl group bound to the omega-nitrogen of N omega-hydroxyornithine. The sequence of three components was determined to be L-N-(2,3-dihydroxybenzoyl)threonyl-L-(N omega-acetyl-N omega-hydroxy)ornithine by mass spectrometric analysis. This structure was confirmed by the total synthesis of vanoxonin.

Dipeptides↗
PubMed1985

Vanoxonin, a new inhibitor of thymidylate synthetase. III. Inhibition of thymidylate synthetase by vanoxonin-vanadium complex.

Quinquevalent vanadium complex with two mol of vanoxonin ligated by the two catechols was shown to be the active structure for inhibition of thymidylate synthetase. The catechol group of vanoxonin as the essential moiety for the inhibition of enzyme was further confirmed by studies of structure-activity relationships using the enzyme obtained from Ehrlich ascites carcinoma cells of mice. Vanoxonin-vanadium complex showed competitive inhibition with respect to deoxyuridylic acid but uncompetitive to 5,10-methylenetetrahydrofolate.

Dipeptides↗
PubMed1981

Gas chromatographic determination of propionic acid in bread and cake.

A simple and accurate method is presented for gas-liquid chromatographic (GLC) determination of propionic acid in bakery products. Propionic acid is extracted with a mixture of dichloromethane and formic acid to which isobutyric acid has been added as an internal standard. The extract is injected directly into the GLC system. A glass column packed with 5% SP-1000 is used. The simplicity and convenience of the method make it suitable for routine determination.

Bread↗
PubMed1980

High performance liquid chromatography of thiabendazole residues in banana citrus fruits.

A simple high performance liquid chromatographic (HPLC) method for determining thiabendazole in fruits has been developed. Thiadazole is extracted with methanol and the extract is washed with n-hexane saturated with methanol. The determination is carried out by HPLC with fluorometric detection. LiChrosorb RP-8 is used as stationary phase and methanol-0.28% ammonia water (60+60) as mobile phase; alpha-methylindole is added as an internal standard. The limit of detection of this method is 0.1 microgram thiabendazole/g. Recoveries are more than 92%.

Chromatography, High Pressure Liquid↗
PubMed1978

Residual piperonyl butoxide in agricultural products.

The residual levels of piperolyn butoxide (PB) in agricultural products were investigated for 531 samples of 10 species. For the determination of PB a high speed liquid chromatograph equipped with a fluorometric detector was used. The detection limit of PB was 0.1 ppm. PB was detected from 3 barleys and 3 wheats harvested in U.S.A. ans Australia. It was not detected from the others. The residual range was from 0.2 to 1.4 ppm.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Isolation of a novel tyrosine kinase inhibitor, lavendustin A, from Streptomyces griseolavendus.

A potent tyrosine kinase inhibitor, lavendustin A [1], has been isolated from a butyl acetate extract of Streptomyces griseolavendus culture filtrate. It inhibits epidermal growth factor receptor-associated tyrosine kinase with an IC50 of 4.4 ng/ml, which is about 50 times more inhibitory than erbstatin. It does not inhibit protein kinase A or C. Its structure, determined by spectral data and total synthesis, is novel, having a tertiary amine in the center with substituted benzyl and phenyl groups. Lavendustin A competes with ATP and is noncompetitive with the peptide. Its structure-activity relationship is discussed.

Magnetic Resonance Spectroscopy↗
PubMedDate not supplied

Suppression of type II collagen-induced arthritis by a new isocoumarin, NM-3.

The anti-arthritic effect of NM-3, a new isocoumarin, was examined using a type II collagen-induced arthritis model for human rheumatoid arthritis in DBA/1J mice. NM-3 by oral administration suppressed dose-dependently (2-20 mg/kg/day) not only macroscopic changes such as erythema and swelling of limbs but also histopathologic changes and radiographic changes such as bone lesions. The efficacy of NM-3 was greater than those of disease-modifying anti-rheumatoid drugs (DMARDs), auranofin (40 mg/kg/day) and bucillamine (10 mg/kg/day). NM-3 failed to suppress carageenan-induced edema and to inhibit the activities of inflammation-related enzymes including cyclooxygenase-1 and -2, 5-lipoxygenase and phospholipase A2, suggesting that the mode of anti-arthritic action of NM-3 may be different from those of non-steroidal anti-inflammatory agents (NSAIDs). Since NM-3 inhibits angiogenesis in a mouse dorsal air-sac model, the observed anti-arthritic effect of NM-3 might be partly attributed to the antiangiogenic activity. Thus, NM-3 is a potential orally active therapeutic agent for the treatment of human rheumatoid arthritis.

Animals↗