Structure elucidation of natural products from bacteria of the genus Streptomyces

In der vorliegenden Arbeit werden acht neue Naturstoffe aus vier verschiedenen Bakterienstämmen der Gattung Streptomyces in ihrer chemischen Struktur beschrieben. Zur Strukturaufklärung wurden umfangreiche massenspektrometrische und NMR-spektroskopische Analysemethoden eingesetzt. Bei den Naturstoffen handelt es sich zum einen um sieben Vertreter der Klasse I-Polyketide, zu anderen um einen Vertreter der Aranciamycine, welche aus einem kondensierten, hocharomatischen System der Klasse II-Polyketide bestehen. Die Bakterienstämme sind ausschließlich der Gattung Streptomyces zuzuordnen, wobei diese jedoch aus völlig unterschiedlichen Habitaten isoliert wurden. Während die eine Gruppe von Stämmen aus einem mitteleuropäischen Nadelwald isoliert worden ist, kommt ein weiterer Stamm aus der Atacamawüste, welche mit ihren extremen klimatischen Bedingungen eine der trockensten Orte der Erde darstellt. Im Anschluss an ihre strukturchemische Charakterisierung wurden die Verbindungen in verschiedenen biologischen Testsystemen auf ihre Wirkung hin untersucht. Dabei zeigte sich ein breites Wirkspektrum der unterschiedlichen Substanzen bei antibakteriellen, antitumor- und enzyminhibierenden Testierungen. Die hierbei gewonnen Erkenntnisse tragen zu einem besseren Verständnis über Struktur und Wirkung von Naturstoffen bei.In the present study, eight new natural products from four different strains of bacteria of the genus Streptomyces were described in their chemical structure. The structure elucidation was done on the basis of extensive mass spectrometry and NMR spectroscopic analysis. Among the eight natural products, seven compounds belong to the class I polyketides, and the eighth is a representative of the group of aranciamycins, which consist of a condensed, highly aromatic structure of the class II polyketides. The bacterial strains are exclusively assigned to the genus Streptomyces, which were isolated from completely different habitats. While one group of strains has been isolated from a central European coniferous forest, another strain comes from the Atacama Desert, which is due to their extreme climatic conditions, one of the driest places on earth. Following their structural characterization, the compounds were tested in different biological test systems. Among the different substances, the biological tests revealed a wide spectrum of antibacterial, anticancer and enzyme inhibitory activity. The findings obtained here contribute to a better understanding of the structure and activity of natural substances

Silvalactam, a 24-membered macrolactam antibiotic produced by Streptomyces sp Tu 6392

Streptomycetes were isolated out of a soil sample taken from the rhizosphere of a spruce stand and screened by HPLC-diode array analysis for the production of secondary metabolites. This led to the detection of silvalactam, a novel 24-membered macrolactam antibiotic in extracts of Streptomyces strain Tu 6392. The structure was determined by MS and NMR spectroscopy experiments. Silvalactam shows a potent antiproliferative activity against various cancerous and non-cancerous cell lines. The Journal of Antibiotics (2012) 65, 369-372; doi: 10.1038/ja.2012.33; published online 9 May 201

Two new aurachins from Rhodococcus sp. Acta 2259*

In the course of our HPLC screening program, we investigated freshly isolated actinomycete strains from selected terrestrial and limnetic habitats with the aim of detecting novel drugs for pharmaceutical applications. The strains were grown in submerged culture in different media, and extracts prepared from mycelia and culture filtrates at various fermentation times

Plantazolicin, a Novel Microcin B17/Streptolysin S-Like Natural Product from Bacillus amyloliquefaciens FZB42 ▿

Here we report on a novel thiazole/oxazole-modified microcin (TOMM) from Bacillus amyloliquefaciens FZB42, a Gram-positive soil bacterium. This organism is well known for stimulating plant growth and biosynthesizing complex small molecules that suppress the growth of bacterial and fungal plant pathogens. Like microcin B17 and streptolysin S, the TOMM from B. amyloliquefaciens FZB42 undergoes extensive posttranslational modification to become a bioactive natural product. Our data show that the modified peptide bears a molecular mass of 1,335 Da and displays antibacterial activity toward closely related Gram-positive bacteria. A cluster of 12 genes that covers ∼10 kb is essential for the production, modification, export, and self-immunity of this natural product. We have named this compound plantazolicin (PZN), based on the association of several producing organisms with plants and the incorporation of azole heterocycles, which derive from Cys, Ser, and Thr residues of the precursor peptide

Fast Filtration of Bacterial or Mammalian Suspension Cell Cultures for Optimal Metabolomics Results - Fig 5

<p>A. Comparison of metabolite levels for centrifuged (no washing) in contrast to MxP® FastQuench (with washing) samples of NS0 cells. Impact of sampling on metabolite levels for selected metabolites with especially misleading results for centrifuged (no washing) in contrast to MxP^® FastQuench (with washing) samples. B Extracellular levels of glucose and lactate as well as cell viability and total cell number for comparisons</p

Efficient Cluster-Based Catalysts for Asymmetric Hydrogenation of α-Unsaturated Carboxylic Acids.

The new clusters [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)], [H(4) Ru(4) (CO)(10) (1,1-P-P)] and [H(4) Ru(4) (CO)(11) (P-P)] (P-P=chiral diphosphine of the ferrocene-based Josiphos or Walphos ligand families) have been synthesised and characterised. The crystal and molecular structures of eleven clusters reveal that the coordination modes of the diphosphine in the [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)] clusters are different for the Josiphos and the Walphos ligands. The Josiphos ligands bridge a metal-metal bond of the ruthenium tetrahedron in the "conventional" manner, that is, with both phosphine moieties coordinated in equatorial positions relative to a triangular face of the tetrahedron, whereas the phosphine moieties of the Walphos ligands coordinate in one axial and one equatorial position. The differences in the ligand size and the coordination mode between the two types of ligands appear to be reflected in a relative propensity for isomerisation; in solution, the [H(4) Ru(4) (CO)(10) (1,1-Walphos)] clusters isomerise to the corresponding [H(4) Ru(4) (CO)(10) (μ-1,2-Walphos)] clusters, whereas the Josiphos-containing clusters show no tendency to isomerisation in solution. The clusters have been tested as catalysts for asymmetric hydrogenation of four prochiral α-unsaturated carboxylic acids and the prochiral methyl ester (E)-methyl 2-methylbut-2-enoate. High conversion rates (>94 %) and selectivities of product formation were observed for almost all catalysts/catalyst precursors. The observed enantioselectivities were low or nonexistent for the Josiphos-containing clusters and catalyst (cluster) recovery was low, suggesting that cluster fragmentation takes place. On the other hand, excellent conversion rates (99-100 %), product selectivities (99-100 % in most cases) and good enantioselectivities, reaching 90 % enantiomeric excess (ee) in certain cases, were observed for the Walphos-containing clusters, and the clusters could be recovered in good yield after completed catalysis. Results from high-pressure NMR and IR studies, catalyst poisoning tests and comparison of catalytic properties of two [H(4) Ru(4) (CO)(10) (μ-1,2-P-P)] clusters (P-P=Walphos ligands) with the analogous mononuclear catalysts [Ru(P-P)(carboxylato)(2) ] suggest that these clusters may be the active catalytic species, or direct precursors of an active catalytic cluster species

Comparison of metabolite profiles of NS0 cells following sampling with MxP^® FastQuench (FQ) versus centrifugation (C) without washing.

<p>A: PCA of all samples showing very high difference in metabolite levels between both sampling methods. B: Volcano-plot of ANOVA comparison (all C samples versus all FQ, corrected for culture duration) demonstrating that most metabolites had significantly higher levels in centrifuged samples than in filtered. Pluses mark supplemented metabolites and crosses essential supplemented metabolites.</p

Impact of vacuum strength on glutamate, ATP and AMP levels in CHO cells, in filtrate or in washing solution was low (5 replicates, all scales are logarithmic).

<p>All other quantified metabolites (GSH, NAD, ADP, G6P) exhibited similar curves and are not shown for the sake of clarity. The example metabolites were selected due to their biological interest, size difference, cell culture medium content (e.g. glutamate) or in literature described possible leakage [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159389#pone.0159389.ref025" target="_blank">25</a>]. Metabolite level changes compared to 35 mbar were not statistically significant (Student’s t-test, all p values above 0.05).</p

Overview of the steps from sample to peak naming the most critical factors for each step

<p>Overview of the steps from sample to peak naming the most critical factors for each step</p