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Biomedical subjects

P Sedmera

Publications and source records attributed to P Sedmera.

11 recordsLinked to original sources
PubMed1991

Macrotetrolide antibiotics produced by Streptomyces globisporus.

Macrotetrolides isolated from a new producer, Streptomyces globisporus, were identified as nonactin, monactin, dinactin and trinactin. Spectroscopic characterization of these compounds was extended by 13NMR spectra. Chemical ionization with ammonia as reactive gas was proposed for mass-spectroscopic characterization of their mixtures. Their biological activity was confirmed by using larvae of the Colorado potato beetle (Leptinotarsa decemlineata) as a new test model.

Animals↗
PubMed1990

2,3'-anhydrosucrose.

Alkaline hydrolysis of alpha-D-glucopyranosyl 3,4-anhydro-beta-D-ribo-hexulofuranoside (1) involves participation of HO-2 and leads to 2,3'-anhydrosucrose (2). The structure of 2 was assigned on the basis of the n.m.r. and mass spectra of its hexa-acetate 3 and confirmed by the formation from 2 of the 6,6'-di-(4) and 6,1',6'-tri-O-trityl (5) derivatives, the 4,6-O-isopropylidene derivative (6), and 2,3':3,4-dianhydro-galacto-sucrose, isolated as the tetra-acetate 7. The structure of 7 was confirmed by its conversion into the 4'-O-tosyl-6,1',6'-O-trityl derivative 14 and by unambiguous synthesis from 6.

Carbohydrate Sequence↗
PubMed1989

Microbial transformation of semisynthetic derivatives of daunomycinone modified in ring A.

Semisynthetic derivatives of daunomycinone with 7,9-isopropylacetal, 7-O-methyl, 7-O-(4-penten-2-yl), and 7-O-(2-hydroxyethyl) substituents were converted by Streptomyces peucetius var. caesius (an adriamycin-blocked mutant) into 7-deoxy-13-dihydrodaunomycinone, while daunomycinone was transformed into 13-dihydrodaunomycinone (predominantly) and 7-deoxy-13-dihydrodaunomycinone. S. coeruleorubidus mutants 24-74 (accumulating aclavinone derivatives instead of daunomycin and related compounds) and 96-85 (producing no anthracycline substances), and S. aureofaciens B-96 (a tetracycline-blocked mutant) transformed the above substrates into the corresponding 13-dihydro derivatives, with the exception of 7,9-isopropylacetal daunomycinone which remained intact. 7-O-Propyn-1-yl daunomycinone was not transformed by any of the strains used under the conditions.

Naphthacenes↗
PubMed1978

Glucose-2-oxidase activity and accumulation of D-arabino-2-hexosulose in cultures of the basidiomycete Oudemansiella mucida.

Submerged cultures of the basidiomycete Oudemansiella mucida, strain III, accumulate D-arabino-2-hexosulose. The maximum yields during cultivations in shaker flasks or in a laboratory fermentor are 6--12 and 15 mg/ml, respectively (20--50% conversion of substrate glucose). The accumulation is transient, the aldoketose being again utilized after glucose exhaustion. Its production is stimulated by fluoride ions. The enzyme responsible for the C(2)-specific oxidation of D-glucose acts as an intracellular oxidase with a maximum activity in the exponential phase of growth. D-arabino-2-Hexosulose was also detected in the cultivation medium of the wood-rotting fungi Pleurotus ostreatus, Laetiporus sulphureus, and Phellinus abietis.

Basidiomycota↗
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↗