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T Rezanka

Publications and source records attributed to T Rezanka.

At least 37 records · Page 2Linked to original sources
PubMed2001

Glycoside esters from lichens of central Asia.

Ten compounds isolated from the extract of the central Asian lichens comprised new glycosides and glycoside esters having 18R-hydroxy-dihydroalloprotolichesterinic, 18S-hydroxy-dihydroprotolichesterinic and 18S-hydroxy-neodihydroprotolichesterinic acids, as the aglycones and a saccharide moiety linked at C-18 and also at C-21 made by glucose, xylose or rhamnose. The structures were elucidated using extensive spectroscopic analysis (1D and 2D NMR, MS, IR, UV and ORD) and by biochemical methods.

Esters↗
PubMed2001

Macrolactone glycosides of three lichen acids from Acarospora gobiensis, a lichen of Central Asia.

The compounds isolated from the extract of Central Asian lichen (Acarospora gobiensis H. Magn.) comprised three new glycosides having 18-hydroxy-dihydroalloprotolichesterinic, 18-hydroxy-neodihydroprotolichesterinic and 18-hydroxy-dihydroprotolichesterinic acids as aglycones and a di- or trisaccharide moiety linked at C-18 and at the carboxylic group. These compounds, called gobienines A-C, were found to be di- or trisacharides forming a macrolactone with the aglycone. The structures were elucidated by using extensive spectroscopic analysis (1D and 2D NMR, MS, IR and ORD) and chemical and enzymatic methods.

Glycolipids↗
PubMed2000

Analysis of very long chain polyunsaturated fatty acids using high-performance liquid chromatography - atmospheric pressure chemical ionization mass spectrometry.

The presence and identity of very long chain polyunsaturated fatty acids from three freshwater crustacean species, Bathynella natans, B. baicalensis and Baicalobathynella magna from Lake Baikal and caves of central Europe were determined by means of liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization (LC-MS with APCI). LC-MS with APCI enabled the identification of more than 50 very long chain polyunsaturated fatty acids. These acids were described in the crustaceans for the first time, predominantly 26:5n6, 28:7n6, 30:7n3 and 40:7n6. A hypothesis for the biosynthesis of these acids is proposed.

Journal Article↗
PubMed2000

Glycosidic compounds of murolic, protoconstipatic and allo-murolic acids from lichens of Central Asia.

Eleven compounds isolated from the extract of the Central Asian lichens comprised eight new glycosides having murolic, protoconstipatic and allo-murolic acids, as the aglycones and a saccharide moiety linked at C-18 made up of one or two sugars (glucose and apiose or rhamnose or xylose or arabinose). The structures were elucidated by using extensive spectroscopic analysis (1D and 2D NMR, MS, IR, UV and CD) and chemical methods.

Asia, Central↗
PubMed1999

Novel brominated lipidic compounds from lichens of central Asia.

The composition of novel brominated aliphatic compounds from lichens collected during summer from stones around the lake Issyk-Kul (Central Asia) is described. The compounds, predominantly fatty acid derivatives with unique groups (bromine, cyclopropane, oxirane) and conjugated double and triple bonds, were identified by means of 1H and 13C-NMR, MS, IR and UV spectra.

Bromine↗
PubMed1996

Unusually high levels of eicosatetraenoic, eicosapentaenoic, and docosahexaenoic fatty acids in Palestinian freshwater sponges.

The fatty acid compositioin of three freshwater sponges-Ephydatia syriaca, Nudospongilla sp., and Cortispongilla barroisi-were studied. Twenty principal fatty acids, and unusually high levels of eicosatetraenoic (5,8,11,14-20:4 up to 10.1% of the total acid mixture), eicosapentaenoic (5,8,11,14,17-20:5 up to 11.6%), and docosahexaenoic acids (4,7,10,13,16,19-22:6 up to 11.8%) were detected. The only demospongic acid found was 5,9,17-hexacosatrienoic acid (1.8-3.7%).

Animals↗
PubMed1992

Influence of inhibitors of lipid biosynthesis on the production of avermectins in Streptomyces avermitilis.

Streptomyces avermitilis was grown in the presence of four inhibitors of fatty acid biosynthesis (p-chlorophenoxyacetic, DL-2-(p-chlorophenoxy)-propionic, 2-(p-chlorophenoxy)-2-methyl-propionic and p-fluorophenoxyacetic acids). The production of total lipids was inhibited and the cellular content of individual types of fatty acids was altered by these compounds. The anteiso-acid content decreased by up to one-half, whereas the content of iso-odd acids increased 10-fold in the presence of inhibitors. The decrease in anteiso-acids was accompanied by increased production of avermectins having a s-butyl group in the side chain (type 'a' avermectins). It was concluded that the common precursor, 2-methylbutyryl-CoA, was diverted from the biosynthetic pathway of fatty acids to that of avermectins.

Hypolipidemic Agents↗
PubMed1992

Analysis of sterol esters from alga and yeast by high-performance liquid chromatography and capillary gas chromatography-mass spectrometry with chemical ionization.

Sterol esters from the green alga Chlorella kessleri and the yeast Saccharomyces cerevisiae were analysed by tandem high-performance liquid chromatography (HPLC-HPLC). Non-polar lipids were separated by normal-phase HPLC into individual classes and the fraction of sterol esters was subsequently separated by reversed-phase HPLC into intact molecular species. Further separation and identification of the fractions after HPLC were effected by capillary gas chromatography-mass spectrometry (cGC-MS) with positive and/or negative chemical ionization. A technique consisting of direct injection of the sample after its passage through the detector into the on-column injector of the gas chromatograph was used to transfer the sample from HPLC-HPLC to cGC-MS. By means of this method it was possible to demonstrate more than 30 sterols in both the alga and the yeast, and more than 20 new sterol esters were detected.

Chlorophyta↗
PubMed1992

Nitrogen regulation of fatty acids and avermectins biosynthesis in Streptomyces avermitilis.

Fatty acid composition was analysed in the producer of avermectins, Streptomyces avermitilis C-18 grown in chemically defined medium with different nitrogen sources. Significant differences in nitrogen regulation of fatty acid biosynthesis were found in this strain in comparison with other streptomycetes studied so far. This finding could be explained at the level of regulation of branched-chain amino acid metabolism.

Amino Acids, Branched-Chain↗
PubMed1992

Taxonomic studies of Streptomyces virginiae mutants overproducing virginiamycin M1.

By using both the traditional International Streptomycetes Project methods and chemical approaches followed by a hierarchical cluster analysis, Streptomyces virginiae mutants A-1 and B-43 (yielding higher amounts of the M1 component of virginiamycin complex), their wild ancestor ATCC 13161, and another virginiamycin producer, S. pristinaespiralis NRRL 2958, were subjected to taxonomic studies to find kinship or differences among the strains. Of the methods used, only the test of carbon utilization, investigation of spore surface and analysis of sugar constituents of cell walls proved to be reliable enough to demonstrate the species identity of S. virginiae strains and to distinguish them from S. pristinaespiralis. L,L-2,6-Diaminopimelic acid was present in all strains. Analysis of fatty acids and total proteins as well as investigations of morphology and pigmentation of agar cultures led to confusing results.

Electrophoresis, Polyacrylamide Gel↗
PubMed1991

Isobutyrate as a precursor of n-butyrate in the biosynthesis of tylosine and fatty acids.

Labelled sodium isobutyrate [(CD3)2-CHCOONa] was added to the culture medium of Streptomyces fradiae and up to 14 atoms of deuterium were found to be incorporated into a molecule of tylosin aglycone (tylactone). This observation is in accordance with the data in the literature. When fatty acids were analyzed, as much as 34% of the isobutyrate incorporated into the cell was formed to be transformed into butyrate that was used for the synthesis of even, straight-chain fatty acids; 57% of the labelled isobutyrate was incorporated into the even isoacids, whereas 9% was degraded to propionate and further used for the synthesis of the odd acids.

Butyrates↗
PubMed1991

Analysis of human blood plasma triacylglycerols using capillary gas chromatography, silver ion thin-layer chromatographic fractionation and desorption chemical ionization mass spectrometry.

The identification and quantitation from pooled human plasma of over 50 molecular species of triacylglycerols, including 22 not previously reported, are reported. The triacylglycerols were first resolved by silver ion thin-layer chromatography into seven fractions, which were independently analysed by polarizable capillary gas chromatography and desorption chemical ionization mass spectrometry in the presence of an internal standard. The two methods gave similar values for the estimates of oligoenoic species, but the former method underestimated the polyenes (due mainly to significant losses caused by thermal degradation), and the latter method overestimated the saturates. The results show that an effective analysis of molecular species of plasma triacylglycerols cannot be obtained by either technique alone.

Chromatography, Gas↗
PubMed1990

Preparative separation of sphingolipids and of individual molecular species by high-performance liquid chromatography and their identification by gas chromatography-mass spectrometry.

Six fractions containing tri- to pentaglycosylceramides were isolated from the green, fresh water alga Chlorella kessleri, grown heterotrophically, by using preparative high-performance liquid chromatography (HPLC). Up to twelve fractions were obtained by further reversed-phase HPLC of each glycosylceramide. The use of a polar capillary column with Supelcowax 10 as the stationary phase allowed an excellent separation of the individual molecular species of ceramides, even though the separation did not occur when the ceramides differed only in the position of the amide bond. The individual molecular species (even if present in mixtures) were identified by gas chromatography-chemical ionization mass spectrometry. The evidence for a complete structure was obtained by enzyme splitting with alpha- and beta-galactosidases (the sequence of monosaccharides) and by negative ionization fast atom bombardment mass spectrometry. More than 400 molecular species of glycosylceramides were identified.

Ceramides↗
PubMed1989

Quantitative analysis of fatty acid methyl esters by capillary gas chromatography with flame-ionization detection: quadrupole and sector mass spectrometer.

The response of a flame-ionization detector and of two mass detectors, viz. a quadrupole mass spectrometer and a sector mass spectrometer, is described. A relationship between the amount of a fatty acid methyl ester and the relative response in the three detectors was found. The detectors were compared and their possible use for biological samples was discussed.

Carboxylic Acids↗
PubMed1988

Identification of very-long-chain fatty acids in rat and mouse harderian gland lipids by capillary gas chromatography-mass spectrometry.

Lipids of Harderian ophthalmic gland were separated by means of thin-layer chromatography with flame ionization detection in an latroscan apparatus. Wax ester and polar lipids (phosphatidylethanolamine and phosphatidylcholine) were detected as the main lipids in rats and glyceryl ether diester and both polar lipids were the main lipids in mice. Fatty acids were determined in individual lipid classes by means of gas chromatography and gas chromatography-mass spectrometry on capillary columns. The content of fatty acids, the positional isomers of monoenoic acids being predominantly C18, C20 and C22, is most interesting. Very-long-chain fatty acids, saturated fatty acids up to C30 and even monoenoic acids up to C28 were detected. Branched-chain fatty acids, predominantly iso and anteiso, are minority components, although their chain length distribution (C15-C27) is broad.

Animals↗
PubMed1988

Effect of clomiphene on fatty acids, sterols and membrane fluidity in clavine producing Claviceps purpurea strains.

Clomiphene depressed the growth and enhanced clavine production of Claviceps purpurea strains 129,35 and 59. Mycelial content of 18:2 and 16:0 fatty acids decreased, whereas that of 18:1 and 18:0 acids increased. In the mutant strain 59 clomiphene, triadimefon and ergosterol stimulated the impaired function of chanoclavine cyclase. Their effect was counteracted by plant oil. Clomiphene decreased the content of total lipids (44%), triglycerides (32%), sterols (22%) and sterol/phospholipid molar ratio. The PC/PE ratio was 9X increased. Clomiphene and triadimefon enhanced membrane fluidity of protoplasts, ergosterol and oil reverted their effect.

Claviceps↗