Wolf-Rainer Abraham

Terpen-derivate aus Senecio-arten

Zusammenfassung Uberblickt man das jetzt vorliegende Material uber die Gattung Senecio , so bestatigt sich die schon eingangs erwahnte Festellung, das in Eine klare Differenzierung der Gattung Senecio von den Nachbargruppen von der Seite der Inhaltsstoffe her, ist nach wie vor problematisch. Wahrsche

Novel glycine containing glucolipids from the alkane using bacterium Alcanivorax borkumensis.

The polar lipids from the hydrocarbon using and biosurfactant-producing bacterium Alcanivorax borkumensis were isolated and identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. The biosurfactant produced by this species is an anionic glucose lipid with a tetrameric oxyacyl side chain. The glycolipids extracted from the cell wall consist of this biosurfactant N-terminally esterified with glycine. Ten different derivatives of this lipid type were identified and their structures elucidated by MSMS. They vary by the chain length of one or two of the four beta-hydroxy fatty acids (C6, C8 and C10) and by the location of these different fatty acids within the molecule. All compounds are reported here for the first time. In addition to these glycolipids, three different phosphatidylglycerols were identified. While these lipids were found in all strains of A. borkumensis, the relative abundances of the different lipids vary between the strains.

Structural characterization of lichenysin A components by fast atom bombardment tandem mass spectrometry.

The structural characterization of the cyclic lipoheptapeptide surfactant lichenysin A components, produced by Bacillus licheniformis strains via the non-ribosomal pathway on a corresponding peptide synthetase, was carried out using a tandem mass spectrometry (MS/MS) under fast atom bombardment (FAB) conditions. Based on the analysis of the collision-induced fragment-ion spectrum of the single charged molecular ions of both native and partially hydrolyzed forms of lipopeptide, a new general structure of lichenysin A components was elucidated. It varies from previously proposed structure by having in the peptide portion of lipopeptide the L-Gln-1 and L-Asp-5 residues instead of L-Glu-1 and L-Asn-5. The verified chemical structure of lichenysin A was found to be reflected in the structural organization of the corresponding lichenysin A synthetase, LchA, described recently.

Cytochalasins and phytotoxins from the fungus Xylaria obovata

The new metabolites xylobovatin, 19,20-epoxycytochalasin C, deacetyl-19,20-epoxy-cytochalasin C, xylobovide and 4,6,10,12-tridecatetraene-2,8-diol, and the known clonostachydiol and phaseolinon were isolated from the culture broth of the Ethiopian fungus Xylaria obovata. While the cytochalasins are cytotoxins, clonostachydiol is an anthelmintic, and phaseolinon and xylobovide show phytotoxic effects. The formation of these metabolites was studied and the more oxidized cytochalasins were found to be formed late in the fermentation process on moist sterile rice.

Synthesis of galanthamine and related alkaloids - new approaches. I.

Abstract Modifications of protecting groups and of the oxidative coupling conditions lead to pure crystalline intermediates in the synthesis of galanthamine derivatives and gave dienone A in better yields than reported before. The E -configuration of amide 3′ in crystalline state has been determined by X-ray diffraction. Streptomyces affinis 6737 reduces A to the optically active (−)-epigalanthamine derivative C, whose absolute configuration was determined by Bijvoets method. Nematospora corylii CBS 2608 reduces to racemic B. With Ashbya gossypii IFO 1355 a mixture of racemic B and optically active C is obtained. some other microbial transformations are described.

Phospho- and sulfolipids as biomarkers of Caulobacter sensu lato, Brevundimonas and Hyphomonas.

Summary Phospholipids of type strains and isolates of Caulobacter, Brevundimonas, Hyphomonas and Mycoplana bullata were studied by chromatographic and spectroscopic methods. Using tandem mass spectrometry individual phospholipids were analyzed and their structures elucidated. From the 69 strains included in this study 26 new phosphoglucolipids and two new sulfoquinovosyl-diacylglycerols could be identified. While more than 30 different fatty acids were found in the phospholipid fraction of Caulobacter and Brevundimonas only seven different fatty acids occur within the 26 different phosphoglucolipids identified. The distribution of the different types of phospholipids, especially of the sulfoquinovosyl-, glucoronotaurine amide- and phosphatidyl-glucopyranosyl-diacylglycerols, leads to the identification of four different phenotypic groups of these bacteria in agreement with the phylogeny published by Stahl et al. in 1992. One comprises Caulobacter sensu stricto with the type strain C. vibrioides , the second the type strains of Brevundimonas together with a considerable number of Caulobacter species and the third the halophilic Caulobacter spp . around C. maris . The latter group lacks the phosphatidyl-glucopyranosyl-diacylglycerols but contains sulfoquinovosyl- and glucuronotaurine amide diacylgly- cerols. They can be discerned from Hyphomonas by the occurrence of sulfoquinovosyl-diacylglycerols which are absent in strains of the genus Hyphomonas .

Sesquiterpene alcohols with novel skeletons from the fungus ceratocystis piceae (ascomycotina)

Abstract From agar cultures of the ascomycete Ceratocystis piceae Ha 4/82 two sesquiterpene alcohols with novel tricyclic skeletons 1 and 2 have been isolated (cerapicol and ceratopicanol). The biogenesis of the newly identified metabolites is briefly discussed.

Fusalanipyrone, a monoterpenoid from Fusarium solani

Abstract 6-(2′ Z -butenyl)-3-Methyl-α-pyrone was isolated from the fungus Fusarium solani strain DSM 62416 and named fusalanipyrone. This monoterpenoid was not present in F. solani strain DSM 62413.

Neue diterpene und neue dihydrochalkon-derivate sowie weitere inhaltsstoffe aus Helichrysum-arten

Abstract The investigation of 25 further Helichrysum species afforded in addition to known compounds a new diterpene, an oxo-geranyllinalol, a second one, most probably a cembrene derivative, and three dihydrochalkone derivatives. The distribution of the constituents in South African Helichrysum species is discussed briefly.

12, 13-Dihydroxy-fumitremorgin C from Aspergillus fumigatus.

Abstract A new fumitremorgin, 12,13-dihydroxy-fumitremorgin C, was isolated from Aspergillus fumigatus DSM 790 and its structure elucidated. It was only produced under resting cell conditions.