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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 127 records · Page 7Linked to original sources
PubMed1995

Tetrodecamycin and dihydrotetrodecamycin, new antimicrobial antibiotics against Pasteurella piscicida produced by Streptomyces nashvillensis MJ885-mF8. I. Taxonomy, fermentation, isolation, characterization and biological activities.

The novel antimicrobial antibiotic against Pasteurella piscicida, tetrodecamycin (1) and weakly active dihydrotetrodecamycin (2) were isolated from the fermentation broth of Streptomyces nashvillensis MJ885-mF8. They were purified by adsorption on Diaion HP-20, silica gel column chromatography and crystallization. The MICs of 1 were 6.25 approximately 12.5 micrograms/liter and 1.56 approximately 6.25 micrograms/ml against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and 12 strains of P. piscicida, respectively.

Animals↗
PubMed1995

Tetrodecamycin and dihydrotetrodecamycin, new antimicrobial antibiotics against Pasteurella piscicida produced by Streptomyces nashvillensis MJ885-mF8. II. Structure determination.

Novel antimicrobial antibiotics against Pasteurella piscicida, tetrodecamycin (1) and weakly active dihydrotetrodecamycin (2) were isolated from a culture broth of Streptomyces nashvillensis MJ885-mF8. The planar structure of 1 was determined to be 2-acyl-4-ylidene tetronic acid alkyl ether containing decaline ring by various NMR spectral data of 1 and its acetyl derivative (3). The structure of 2 was elucidated by comparison with the spectral data of 1 and confirmed by catalytic reduction of 1 into 2. The X-ray crystallography of 2 showed the relative stereochemistry. Their absolute configurations were determined by using modified Mosher's method.

Anti-Bacterial Agents↗
PubMed1995

Azicemicins A and B, new antimicrobial agents produced by Amycolatopsis. II. Structure determination.

A new structural class of antibiotics, azicemicins A (1) and B (2) were isolated from the culture broth of Amycolatopsis sp. MJ126-NF4. Their structures were elucidated from their physico-chemical properties, various NMR experiments and chemical transformations and were shown to be 3-(1-methyl-2-aziridinyl)- and 3-(2-aziridinyl)-3,4-dihydro-3,7,8,10,12b-pentahydroxy-9,12-dimeth oxy-benz [a]anthracene-1,6(2H,5H)-dione, respectively.

Actinobacteria↗
PubMed1995

New anthracycline antibiotics 10-epi-oxaunomycin and 10-epi-11-deoxyoxaunomycin.

Two new anthracycline antibiotics, 10-epi-oxaunomycin and 10-epi-11-deoxyoxaunomycin, were photochemically obtained from anthracycline metabolites D788-1 (10-carboxy-13-deoxocarminomy-cin) and D788-3 (10-carboxy-11-deoxy-13-deoxocarminomycin) and were examined for their growth inhibitory activities on cultured L1210 leukemic cells. Effects of the S configuration of C-10 and a hydroxyl group at C-11 on the bioactivity are discussed in comparison with oxaunomycin and 11-deoxyoxaunomycin.

Animals↗
PubMed1995

Derivatives of tetrodecamycin.

The derivatives of tetrodecamycin (1), being introduced acyl, carbamoyl and alkyl groups at 14-hydroxyl group and modified at exo-methylene group, were synthesized and evaluated on their antibacterial activities. Although 14-O-substituted tetrodecamycins (3 approximately 19) showed weak activity against Pasteurella piscicida, they were more active against Gram-positive bacteria than 1. Among them, 15 showed approximately 10-fold higher activity than 1. The derivatives (20 approximately 23) modified at 4 or 5 positions had moderate antibacterial activity. The absolute structure of 4(R),5-dibromotetrodecamycin (23) was determined by X-ray crystallographic analysis.

Anti-Bacterial Agents↗
PubMed1995

Synthesis and protein tyrosine phosphatase inhibitory activity of dephostatin analogs.

We have synthesized derivatives of dephostatin, a protein tyrosine phosphatase (PTPase) inhibitor, to study the structure-activity relationships of this inhibitor. Inactive analogs revealed some insight into structural requirements or PTPase inhibitory activity of dephostatin. Both a nitroso group and phenolic hydroxyl groups were found to be essential for the inhibitory activity. Among the dephostatin derivative synthesized, one of the regioisomers of dephostatin showed PTPase inhibitory activity equivalent to that of dephostatin, and also had increased stability.

Enzyme Inhibitors↗
PubMed1995

Antitumor activity of cytogenin.

Antitumor effect of cytogenin against IMC carcinoma in mice was investigated. Since cytogenin did not show cytotoxicity against tumor cells in vitro at 50 micrograms/ml and toxicity at more than 2,000 mg/kg i.p., it was considered that the antitumor effect is due to host mediated events. Cytogenin showed antitumor activity against a syngeneic murine transplantable tumor, IMC carcinoma by oral administration depending upon schedule of administration. The optimum effect was observed by the administration starting day 8 after transplantation of tumor cells, every other day for 10 times or every 2nd day for 7 times. The antitumor effect was reduced in immunosuppressed mice given anti-asialo GM1 serum and in athymic mice, but not in mice irradiated with X ray. The antitumor effector cells activated by cytogenin were determined to be macrophages and T cells.

Animals↗
PubMed1995

Azicemicins A and B, a new antimicrobial agent produced by Amycolatopsis. I. Taxonomy, fermentation, isolation, characterization and biological activities.

A new structural class of the antibiotic, azicemicins A (1) and B (2) were isolated from the culture broth of the strain MJ126-NF4, which was closely related to Amycolatopsis sulphurea. They were purified by adsorption on Diaion HP-20, silica gel column chromatography and preparative TLC. The molecular formulas of 1 and 2 were determined to be C23H25O9N and C22H23O9N by HRFAB-MS, respectively. Azicemicins A and B have moderate growth inhibiting activity against Gram-positive bacteria and mycobacteria.

Actinobacteria↗
PubMed1995

Improvement of efficacy of antitumor agents by conagenin.

The antitumor efficacy of antitumor agents at sublethal doses was investigated in combination with conagenin (CNG) against murine leukemias. Mice were inoculated with 1 x 10(3) L1210 cells i.v. and given 300 mg/kg of cyclophosphamide (CY) i.p. on days 1 and 2 or on days 1, 5 and 9 after the tumor inoculation, and 5 mg/kg of CNG daily for 10 days. The administration of CNG was effective in increasing the number of cured mice and in prolonging the survival period of mice significantly, on both schedules of CY treatment. Moreover, the antitumor effect of CY against EL-4 was enhanced by CNG in increasing the number of cured mice, in CY treatment on days 1 and 2, and on days 1, 5 and 9. The effect of CNG was examined with mitomycin C (MMC) and adriamycin (ADM) at sublethal doses against leukemias. The antitumor effects of MMC at 10 mg/kg against L1210, and ADM at 15 mg/kg against P388 administered on days 1 and 5 were enhanced by CNG. Although mice treated with ADM at 15 mg/kg died earlier than non-treated controls on days 1 and 2 against L1210, P388 and EL-4, CNG with ADM was effective in prolonging the survival period.

Adjuvants, Immunologic↗
PubMed1995

Action of cytogenin on lymphoid cells and their cytokine production.

Action of cytogenin on macrophages and T cells was investigated. Phagocytosis of yeast and production of PMA-elicited superoxide anion by macrophages taken from mice given cytogenin po were augmented. Cytogenin enhanced productions of IL-1 alpha by macrophages and IFN gamma and GM-CSF by spleen cells although it did not enhanced production of TNF alpha by macrophages and IL-6 by macrophages and spleen cells. Macrophages stimulated with cytogenin caused to stimulate proliferation of purified T cells in Intercell cultures in which each cell population was cultured without contact. Results suggest that cytogenin primarily activates macrophages to produce monokines such as IL-1 alpha and it causes to stimulate proliferation and differentiation of T cells resulting in production of lymphokines such as IFN gamma and GM-CSF.

Animals↗
PubMed1995

Modulation of macrophage activity in tumor bearing mice by cytogenin.

Cytogenin recovered the reduced mitogenic response to Con A of spleen cells of tumor bearing mice in vitro. The suppressive factor(s) was detected in adherent cell population in spleen cells. The reduced antitumor effector activity of spleen cells taken from tumor bearing mice was also augmented by the treatment with cytogenin in vitro. The effect of cytogenin was neutralized by the treatment with anti-Mac 1 serum. Administration of cytogenin inhibited the production of nitric oxide by macrophages which is known as one of suppressor factors. Results indicate that one possible action of cytogenin exhibiting antitumor activity in tumor bearing mice may be due to modulation of Mac 1 positive cells.

Animals↗
PubMed1995

Thiazinotrienomycins, new ansamycin group antibiotics.

New triene-ansamycins designated thiazinotrienomycins A, B, C, D and E were isolated from culture broth of Streptomyces sp. MJ672-m3 for their activities against cervical cancer cell lines. The structures and some biological and biochemical properties of the antibiotics were determined.

Animals↗