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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 1,531 records · Page 85Linked to original sources
PubMed1987

New tylosin analogs produced by mutants of Streptomyces fradiae.

2'''-Demethoxytylosin (component IIIc), 2'''-demethoxy-4'''-epi-tylosin (component IIId) and 2'''-O-demethyltylosin (component Vb) were produced by blocked mutant strains of Streptomyces fradiae. Fermentation, isolation, structure determination and biosynthetic considerations of these tylosin analogs are described.

Chemical Phenomena↗
PubMed1987

New antibiotic napyradiomycins A2 and B4 and stereochemistry of napyradiomycins.

Napyradiomycins A2 and B4, new members of the napyradiomycins, have been isolated from the culture broth of Chainia rubra MG802-AF1. The structure of napyradiomycin A2 was elucidated as 16-hydroxy-17-methylenenapyradiomycin A1 by NMR studies. The absolute structure of napyradiomycin B4 was determined as 13-hydroxy-13-methylnapyradiomycin B1 by X-ray crystallography and therefore the configuration of C(4a) in other napyradiomycins is assumed as the R configuration. The geometrical isomerism of napyradiomycin C1 was estimated as 12E and 16E by nuclear Overhauser effect experiments.

Anti-Bacterial Agents↗
PubMed1987

Synthesis and antitumor activity of spergualin analogues. II. Chemical modification of the spermidine moiety.

Chemical modifications of the spermidine moiety of an antitumor antibiotic, spergualin (Ia), and the structure-activity relationship are described. Replacement of spermidine with other polyamines decreased the antitumor activity against mouse leukemia L1210. Analogues containing an oxidized spermidine moiety that probably formed during oxidation with amine oxidase were inactive. Spermidine is indispensable for the antitumor activity. A facile method for the synthesis of glyoxyloyl polyamine, a key intermediate of spergualin-related compounds, is also reported.

Animals↗
PubMed1987

Synthesis and antitumor activity of spergualin analogues. III. Novel method for synthesis of optically active 15-deoxyspergualin and 15-deoxy-11-O-methylspergualin.

Optically active 15-deoxyspergualin (II) and 15-deoxy-11-O-methylspergualin (IIa) were synthesized, and their antitumor activities were examined. The (-)-enantiomers of both II and IIa were active against mouse leukemia L1210, while the (+)-enantiomers were almost inactive. The optical resolution of the key intermediate, (+/-)-N-(7-guanidinoheptanoyl)-alpha-alkoxyglycine (VI) was achieved by use of an exopeptidase, serine (acid) carboxypeptidase [EC 3.4.16.1] and (+/-)-N-(7-guanidinoheptanoyl)-alpha-alkoxyglycyl-L-amino acid (VIII) as the substrate. Considering the enzymatic susceptibility of the substrate (VIII), we deduced that the absolute configuration of the carbon at 11 (C-11) of the bioactive (-)-enantiomer, and so that of natural spergualin (I), is S. This is, to our knowledge, the first report of the use of carboxypeptidase for the resolution of N-acyl amino acid.

Animals↗
PubMed1987

Effect of spergualin in autoimmune disease mice.

We investigated the effect of spergualin (SGL) upon the development of spontaneous systemic lupus erythematosus-like lesions in male MRL/MpJ-lpr/lpr mice. SGL was administered ip at doses of 2.5, 5 and 10 mg/kg to two groups of mice. One group received SGL prophylactically from 7 to 21 weeks of age. The other group received SGL curatively from 13 to 27 weeks of age. The occurrence of lupus lesions was characterized by enlarged lymphoid organs, high anti-DNA titer and blood urea nitrogen, and severe glomerular nephritis. In both groups these characteristics were significantly suppressed by SGL in a dose-dependent manner. This inhibitory activity was greatest at a dose of 10 mg/kg. These findings suggest that SGL has prophylactic and curative effects against lupus lesions in autoimmune disease in mice.

Animals↗
PubMed1987

Immunosuppressive activity of 15-deoxyspergualin and its effect on skin allografts in rats.

The immunosuppressive activity of spergualin analogues, 15-deoxyspergualin and N-30, is presented. These compounds suppressed antibody formation and establishment of delayed-type hypersensitivity to sheep red blood cells (SRBC) in mice. Among spergualin, 15-deoxyspergualin, and N-30, 15-deoxyspergualin was most effective in suppressing immune responses. It suppressed antibody formation against SRBC by spleen cell cultures in a dose-dependent fashion without reducing cell viability. The spergualins also suppressed the mixed lymphocyte culture reaction. Peritoneal exudate cells taken from mice given immunosuppressive doses of 15-deoxyspergualin were not reduced in their functions measured: Release of lysosomal enzymes and production of superoxide anions. 15-Deoxyspergualin and N-30 were markedly effective in prolonging skin graft in rats.

Animals↗