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Biomedical subjects

H Imanaka

Publications and source records attributed to H Imanaka.

At least 109 records · Page 6Linked to original sources
PubMed1985

Lavendomycin, a new antibiotic. I. Taxonomy, isolation and characterization.

Lavendomycin, a new basic peptide antibiotic containing novel amino acids, has been isolated from the culture broth of a streptomyces designated as Streptomyces lavendulae subsp. brasilicus. The antibiotic obtained as colorless crystals (C29H50N10O8, MW 666) is active against Gram-positive bacteria in vitro and in vivo, however, inactive against Gram-negative bacteria and fungi. An acute toxicity of the antibiotic in mice was LD50 greater than 2 g/kg by subcutaneous injection.

Animals↗
PubMed1985

New antitumor antibiotics, FR-900405 and FR-900406. I. Taxonomy of the producing strain.

An actinomycete which was isolated from a soil sample produces new antitumor substances. The morphological and cultural characteristics of the strain resemble those of the genera Streptomyces Waksman and Henrici 1943 and Actinomadura Lechevalier and Lechevalier 1970. Cell wall composition analysis showed that strain No. 6049 contained meso-2,6-diaminopimelic acid in its cell wall, and madurose in whole-cell sugars. No sporangia, zoospores or fragmentations of vegetative mycelium are observed. From these results, strain No. 6049 is designated as Actinomadura pulveracea sp. nov.

Actinomycetales↗
PubMed1985

New antitumor antibiotics, FR-900405 and FR-900406. II. Production, isolation, characterization and antitumor activity.

The new antitumor antibiotics, FR-900405 and FR-900406, were isolated from the culture broth of Actinomadura pulveracea sp. nov. No. 6049. These compounds which contain sulfur in the molecule, represent a novel class of antitumor agents. FR-900405 and FR-900406 are highly active in mice against experimental tumors and exhibit antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi.

Actinomycetales↗
PubMed1985

Studies of an immunomodulator, swainsonine. I. Enhancement of immune response by swainsonine in vitro.

Swainsonine isolated from Metarhizium sp., was found to enhance the activities of the mouse immune system in vitro. Concanavalin A stimulated lymphocyte proliferation and proliferative response in mixed lymphocytes culture, which were suppressed by immunosuppressive factor obtained from serum of sarcoma 180 tumor bearing mouse, were restored to normal levels by the addition of swainsonine. Furthermore, the concanavalin A induced incorporation of [3H]thymidine into mouse spleen cells was remarkably increased by treatment with swainsonine over a wide dose range, From studies using fluorescence activated cell sorting, swainsonine was shown to enhance the expression of concanavalin A receptors of spleen cells.

Adjuvants, Immunologic↗
PubMed1985

Studies of an immunomodulator, swainsonine. II. Effect of swainsonine on mouse immunodeficient system and experimental murine tumor.

We examined the effect of swainsonine on antibody response to sheep red blood cells (SRBC) in immunodeficient mice which were treated with immunosuppressive factor or antitumor drugs, or inoculated with sarcoma 180 ascites tumor. The administration of swainsonine restored the capacities of the immunodeficient mice to produce antibody against SRBC. Furthermore, swainsonine inhibited completely the growth of sarcoma 180 ascites tumor in mice. Swainsonine also reduced lung metastases of B16 melanoma in mice. These results suggest that swainsonine has potential as an immunomodulator for the treatment of immunocompromised hosts.

Adjuvants, Immunologic↗
PubMed1985

Activation of tumoricidal properties in macrophages and inhibition of experimentally-induced murine metastases by a new synthetic acyltripeptide, FK-565.

The effect of FK-565, a novel low molecular weight (MW) acyltripeptide, on tumoricidal properties of murine macrophages is reported here. Peritoneal macrophages (PMs) harvested from C57BL/6 mice and beige mice were rendered cytotoxic to syngeneic B16 melanoma cells following their interaction in vitro with FK-565. Maximal and reproducible activation of tumoricidal properties in PM were obtained by interaction in vitro with 25 micrograms/ml of FK-565 for a 24 h period, and as little as 0.5 microgram/ml of FK-565 was sufficient to induce significant cytotoxicity. Murine PMs activated by FK-565 in vitro were cytotoxic to syngeneic and xenogeneic tumor cells, but did not affect allogeneic nontumor cells. The PMs were also activated to kill B16 melanoma cells by intraperitoneal injections of FK-565 (10 mg/kg). Multiple injections of FK-565 into mice also slightly but significantly inhibited lung metastases. These results suggest that FK-565 has potential as an effective immunopotentiator in immunotherapy.

Adjuvants, Immunologic↗
PubMed1984

Studies on new antiplatelet agents, WS-30581 A and B.

WS-30581 A and B are antiplatelet agents produced by a strain of Streptoverticillium waksmanii. The compounds were purified by solvent extraction and column chromatography, and identified as new pimprinine analogs on the basis of their physico-chemical properties. The producing organism produced pimprinine along with these compounds. Pimprinine and the two new analogs have potent inhibitory effects on platelet aggregation.

Animals↗
PubMed1984

Chryscandin, a novel peptidyl nucleoside antibiotic. I. Taxonomy, fermentation, isolation and characterization.

A novel antifungal antibiotic, chryscandin was found in the culture broth of a strain of fungi. The producing organism was subsequently identified as Chrysosporium pannorum. The antibiotic obtained as colorless needle crystals (C20H23N7O6, MW 457) is active against Candida albicans and Gram-positive bacteria, but it is ineffective against filamentous fungi and Gram-negative bacteria. Acute toxicity is very low in mice.

Animals↗
PubMed1984

Chryscandin, a novel peptidyl nucleoside antibiotic. II. Structure determination and synthesis.

The structure of chryscandin, a novel antifungal antibiotic, produced by Chrysosporium pannorum No. 4629 was deduced to be 1 from spectroscopic and chemical evidences. In order to confirm the structure and to determine the absolute configuration, the total synthesis of chryscandin was performed. D-Xylose was transformed into 10 in ten steps. After beta-glycosidation of silylated benzoyl adenine with 10, the resulting 11 was converted into 4, which was identical with the product obtained from chryscandin by alkaline hydrolysis. From the key intermediate 13, chryscandin was synthesized via peptide formation followed by removal of the protecting groups. Chryscandin (1) is the first naturally occurring nucleoside antibiotic possessing a 3-aminoribofuranuronic acid in the molecule.

Antifungal Agents↗
PubMed1984

Amauromine, a new vasodilator. Taxonomy, isolation and characterization.

Amauromine is a new alkaloid with vasodilating activity obtained from the culture broth of Amauroascus sp. No. 6237. Its molecular formula was determined to be C32H36N4O2 on the basis of elementary analysis and high resolution mass spectroscopic measurement. It has low toxicity in mice.

Alkaloids↗
PubMed1984

Studies on WF-5239, a new potent platelet aggregation inhibitor.

WF-5239 was produced by a fungal strain identified as Aspergillus fumigatus Fresenius. The substance was purified by solvent extraction followed by chromatography on silica gel and then crystallized (C9H9NO2, mp 142 approximately 145 degrees C). The chemical structure was determined from its physico-chemical properties as N-[2-cis(4-hydroxyphenyl)ethenyl]formamide. WF-5239 has inhibitory activity against rabbit platelet aggregation induced by arachidonic acid and collagen, with IC50 values of 1.25 and 5.0 micrograms/ml, respectively. Arachidonic acid induced mortality in mice was reduced by a single intraperitoneal dose of WF-5239 (30 mg/kg). These biological properties have been compared with those of aspirin.

Animals↗
PubMed1983

Studies on a new antibiotic FR-900109. 1. Taxonomy, isolation and characterization.

FR-900109 is a new antibiotic obtained from fermentation broth of a streptomyces which was identified as Streptomyces prunicolor. Its elementary analysis and mass spectroscopic measurement suggest that the molecular formula is C27H32O9. It has an ultraviolet absorption maximum at 254 nm. The antibiotic is active against Gram-positive bacteria. Acute toxicity in mice is very low.

Anti-Bacterial Agents↗
PubMed1983

Studies on WF-3161, a new antitumor antibiotic.

WF-3161 is an antitumor antibiotic produced by a strain of fungus, Petriella guttulata. The antibiotic was purified by solvent extraction and a combination of silica gel and reverse phase column chromatography. The chemical structure of the antibiotic (C31H44N4O6, mp 181-183 degrees C) was found to be a cyclic tetrapeptide consisting of phenylalanine, leucine, pipecolinic acid and 2-amino-8-oxo-9,10-epoxydecanoic acid. WF-3161 inhibited the growth of Trichophyton asteroides. It prolonged survival period of mice bearing leukemia P-388 with a high therapeutic index.

Animals↗
PubMed1983

Antitumor effects of novel immunoactive peptides, FK-156 and its synthetic derivatives.

Effects produced by intratumor or systemic application of FK-156 and its synthetic derivatives on the syngeneic P388-DBA/2 mouse system were investigated. Among 21 compounds tested, FK-156, FK-565, FR-46758, FR-48217, FR-46091 and FR-47920 substantially suppressed tumor growth when directly injected into a tumor mass and further experiments showed that FK-156, FK-565 and FR-46758 were effective even when administered subcutaneously into site remote from tumor. The mechanisms of growth inhibition are strongly suggested to be host mediated, because these three compounds have remarkably low cytotoxicity against P388 cells in vitro. A single dose of FK-565, however, markedly decreased body weight in healthy DBA/2 mice, whereas FK-156 and FR-46758 did not. These results indicate the superiority of FK-156 and FR-46758 as immunotherapeutic agents over FK-565 with respect to their safety for treatment of cancer. Although significant life-span prolongation could not be seen in the two-injection regimen of six compounds in either system, systemic multiple injections of FK-156 and FR-46758 provided a statistically significant increase in the median survival time of P388 tumor bearing mice.

Adjuvants, Immunologic↗