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Biomedical subjects

J Vokoun

Publications and source records attributed to J Vokoun.

14 recordsLinked to original sources
PubMed1989

Production of thermozymocidin (myriocin) by the pyrenomycete Melanconis flavovirens.

Submerged culture of the pyrenomycete Melanconis flavovirens produces a strongly active antifungal antibiotic. The antibiotic was isolated from the culture mash. In purified compound the physico-chemical characteristics, including 1H NMR spectrum, were estimated. The antibiotic was found to be identical with thermozymocidin (myriocin) as confirmed by comparison with synthetically prepared thermozymocidin.

Amino Alcohols↗
PubMed1984

[Anthracycline antibiotics from genetically modified streptomycetes. The isolation, spectroscopic structural elucidation and biologic effects of beta-rhodomycin I].

By mutagenic treatment and selection procedures the mutant ZIMET 43678 was obtained from a population of the interspecific recombinant Streptomyces violaceus subsp. iremyceticus ZIMET 43615, which showed a changed spectrum of secondary metabolites. The main component isolated from the fermentation broth was a pure anthracycline evidenced by TLC. By means of acid hydrolysis, identification of the degradation products and also by spectroscopic UV/VIS-, IR-, MS-, 1H/13C-NMR- and CD-investigations with intact anthracycline the structure 7-(alpha-L- rhodosaminyl )-beta- rhodomycinon with the absolute configuration 7S, 9R , 10R was found. The anthracycline called beta- rhodomycin -1 (1) exhibits antimicrobial and cytostatic activity in vitro and is also effective on tumour cells in tumour bearing animals.

Anthracyclines↗
PubMed1980

Isolation, characterization and biological activities of verotetrone from a mutant strain of Streptomyces aureofaciens.

A new metabolite denoted as verotetrone was isolated from the mycelium of the mutant strain Streptomyces aureofaciens NMG-2. Interpretations of physical data concerning verotetrone and its triacetate and, the determination of its degradation product indicate that verotetrone belongs to pretetramide-type metabolites. Verotetrone exhibits neither antibacterial nor antifungal activity. In vitro it inhibits the synthesis of nucleic acids as well as proteins in Ehrlich ascites carcinoma cells. Both verotetrone and its triacetate interfere in vivo with the metabolism of tumour and lymphoid cells, exhibiting antitumour or immunosuppressive activity. This activity, which is more intense with verotetrone than with its triacetate, is detectable in a dose which is already toxic in some animals.

Animals↗
PubMed1980

Mass spectrometry of ring D hydroxylated 3-methoxy-1,3,5(10)-estratrienes.

Mass spectra and fragmentation patterns of the epimeric 17-, 16-, 15- and 14-hydroxy derivatives of 3-methoxy-1,3,5(10)-estratriene are compared. The main fragmentation pathways are differently influenced, depending on the position of the hydroxy group. The different configuration of the hydroxy groups is reflected only in the spectra of the epimeric 15- and 14-hydroxy compounds. Possibilities of mass spectrometric differentiation between the hydroxy-estratrienes are discussed.

Chemical Phenomena↗
PubMed1978

Eurotium (Aspergillus) repens metabolites and their biological activity.

Eurotium repens mycelium cultivated under static conditions was used to isolate and identify metabolities--echinulin, physcion, erythroglaucin, flavoglaucin and asperentin; the filtrate of the culture yielded asperentin 8-methylether. The broadest biological activity spectrum was displayed by asperentin which had antibacterial and antifungal effects and, at a concentration of 86 microgram/ml, caused 50% mor7 tality in Artemia saline larvae. The highest cytotoxicity towards HeLa cells was found in physcion which caused 50% growth inhibition at a concentration of 0.1 microgram/ml.

Animals↗
PubMed1978

The structure of ekatetrone, a metabolite of strains of Streptomyces aureofaciens.

The structure of ekatetrone has been determined from physico-chemical data obtained using the natural compound, its derivatives and products of degradation reactions. Ekatetrone was found to be the lactone of 1,8-dihydroxy-2-(1'-hydroxy-2'-carbamoyl)ethyl-9,10-anthraquinone-3-acetic acid (I). It is proposed that ekatetrone is related, biogenetically, to protetrone.

Anthraquinones↗
PubMed1977

Anthracyclines.

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Aminoglycosides↗
PubMed1976

Microbial transformation of daunomycinone by Streptomyces aureofaciens B-96.

Daunomycinone, aglycone of the anthracycline antibiotic daunomycin, was transformed by a washed mycelia of Streptomyces aureofaciens B-96 in a buffer solution containing sucrose; the obtained product, dihydrodaunomycinone (9-(1-hydroxyethyl)-7,8,9,10-tetrahydro-6,7,9,11-tetrahydroxy-4-methoxy-5,12-naphthacenequinone), was identified by measuring basic physicochemical characteristics (IR, UV and visible spectra, mass spectra and NMR, optical rotation and m.p.).

Biotransformation↗