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Raju R.,German Center for Infection Research Association | Mohr K.I.,German Center for Infection Research Association | Mohr K.I.,Helmholtz Center for Infection Research | Bernecker S.,Helmholtz Center for Infection Research | And 2 more authors.
Journal of Antibiotics | Year: 2015

Myxobacteria are Gram-negative bacteria that are sources of a large number of compounds with unique structures that possess varying biological activities. They are known to produce secondary metabolites that have more novel structures with those produced by other microbes such as, actinomycetes and fungi. In our search for novel secondary metabolites, Cystobacter ferrugineus strain Cbfe23, which was isolated from a soil sample in China, garnered our attention based on our in-house LC-MS analysis. Specifically, a peak identified with an m/z of 352 did not produce any hits in our mass spectral library of compounds, prompting us to further investigate the strain in detail in order to determine the structural profile of the unknown metabolite. Source


Surup F.,Helmholtz Center for Infection Research | Surup F.,German Center for Infection Research Association | Wiebach V.,Helmholtz Center for Infection Research | Wiebach V.,TU Berlin | And 4 more authors.
Tetrahedron Letters | Year: 2016

Stromata (fruiting bodies) from the xylariaceous fungus Annulohypoxylon truncatum collected in Texas were analyzed for novel secondary metabolites. Two asterriquinone-type pigments named truncaquinones A (1) and B (2) were obtained by preparative HPLC in addition to the known truncatone. Their structures were elucidated by HRESIMS and NMR data. 4J correlations were crucial to assign a methoxy signal in 1; these were observed in HMBC spectra with extended long range evolution delay (Δ) times. The pigments exhibited cytotoxic effects besides weak activity against Gram positive bacteria. © 2016 Elsevier Ltd. All rights reserved. Source


Kuhnert E.,Helmholtz Center for Infection Research | Kuhnert E.,German Center for Infection Research Association | Surup F.,Helmholtz Center for Infection Research | Surup F.,German Center for Infection Research Association | And 7 more authors.
Phytochemistry | Year: 2015

Our screening efforts for new natural products with interesting bioactivity have revealed the neotropical ascomycete Hypoxylon rickii as a prolific source. We isolated five secondary metabolites with a p-terphenyl backbone from the mycelial extract of a fermentation of this fungus in 70. l scale by using RP-HPLC, which were named rickenyls A-E (1-5). Their structures were elucidated by X-ray crystallography and NMR spectroscopy, complemented by HRESIMS. Two of the compounds contained a quinone core structure in ortho (2) and para-position (5), respectively. We obtained 2 spontaneously and by lead tetraacetate oxidation from 1. All compounds were screened for antimicrobial, antioxidative and cytotoxic activities. Rickenyl A (1) exhibited strong antioxidative effects and moderate cytotoxic activity against various cancer cell lines. © 2015 Elsevier Ltd. Source


Kuhnert E.,Helmholtz Center for Infection Research | Kuhnert E.,German Center for Infection Research Association | Surup F.,Helmholtz Center for Infection Research | Surup F.,German Center for Infection Research Association | And 6 more authors.
Phytochemistry | Year: 2015

In the course of our screening for new bioactive natural products, a culture of Hypoxylon rickii, a xylariaceous ascomycete collected from the Caribbean island Martinique, was identified as extraordinary prolific producer of secondary metabolites. Ten metabolites of terpenoid origin were isolated from submerged cultures of this species by preparative HPLC. Their structures were elucidated using spectral techniques including 2D NMR and HRESIMS. Three of the compounds were elucidated as new botryanes (1-3) along with three known ones, i.e. (3aS)-3a,5,5,8-tetramethyl-3,3a,4,5-tetrahydro-1H-cyclopenta[de]isochromen-1-one (4), (3aS,8R)-3a,5,5,8-tetramethyl-3,3a,4,5,7,8-hexahydro-1H-cyclopenta[de]isochromen-1-one (5) and botryenanol (6). Further three new sesquiterpenoids featured a 14-noreudesmane-type skeleton and were named hypoxylan A-C (7-9); the diterpenoid rickitin A (10) contains an abietane-type backbone. Compounds 1, 2, 3, 7, and 10 showed cytotoxic effects against murine cells. © 2015 Elsevier Ltd. All rights reserved. Source

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