1,721,145 research outputs found
Endophenazines A similar to D, new phenazine antibiotics from the athropod associated endosymbiont Streptomyces anulatus II. Structure elucidation
No full textA detailed screening of the secondary metabolite pattern produced by different athropod associated strains of the species Streptomyces anulatus resulted in the isolation and structure elucidation of the endophenazines Asimilar toD (2, 4similar to6). The structures were assigned by spectroscopic methods and chemical transformations. 4 represents a chromophoric system based on a phenazin-7-one, 5 and 6 are new 5, 10-dihydrophenazine derivatives
Endophenazines A similar to D, new phenazine antibiotics from the athropod associated endosymbiont Streptomyces anulatus II. Structure elucidation
No full textA detailed screening of the secondary metabolite pattern produced by different athropod associated strains of the species Streptomyces anulatus resulted in the isolation and structure elucidation of the endophenazines Asimilar toD (2, 4similar to6). The structures were assigned by spectroscopic methods and chemical transformations. 4 represents a chromophoric system based on a phenazin-7-one, 5 and 6 are new 5, 10-dihydrophenazine derivatives
Cytotoxic compounds from a marine actinomycete, Streptomyces albovinaceus var. baredar AUBN(10)/2
No full textMarine sediment samples from Machilipatnam (Krishna District, A. P) coast off Bay of Bengal, India were investigated as a source of actinomycetes to screen for the production of novel bioactive compounds. More than 10,000 bioactive compounds have been described from marine actinomycetes, with many different properties, ranging from colour pigments to cytotoxic compounds. The search for cytotoxic compounds is continuing due to the demand for new anticancer drugs. In this work, compound I was isolated from the marine derived actinomycete strain AUBN(10)/2, obtained from marine sediment samples of Bay of Bengal, India. This was obtained by solvent extraction followed by chromatographic purification. The pure compound I was identified from spectroscopic data which was related to the actinomycin D, it showed a potent cytotoxic activity against cell lines HMO2 (gastric adenocarcinoma) and HePG2 (hepatic carcinoma) in vitro. It also exhibited antimicrobial activities against gram positive and negative bacteria
The medical potential of natural products
No full textNatural products and their derivatives are well established in clinical research and for medical applications. There are excellent drugs available from various plants and microorganisms. Recent developments in the different screening techniques have accelerated the discovery of new compounds. Furthermore,the investigation of compounds of marine origin, which have been more difficult to obtain, has become possible. With the help of combinatorial methods, natural products can be modified to optimize their use for medical applications. Due to the enormous medical potential, modern research on natural products will also be important in the next century
New biologically active rubiginones from Streptomyces sp.
No full textFour new polyketides, named rubiginone D-2 (2), 4-O-acetyl-rubiginone D-2 (3), rubiginone H (6) and rubiginone I (7) were isolated from the cultures of Streptomyces sp. (strain Go N1/5). Their structures were established by a detailed spectroscopic analysis. The absolute configuration of 3 was determined by derivatization with chiral acids (Helmchen's method). The rubiginones inhibit the growth of some Gram-positive bacteria and are cytostatically active against different tumor cell lines
sp.
No full textStreptomyces sp. strain GoM1 was found to produce seven novel glycosides (2-8) containing the rare deoxysugar 6-deoxy-alpha-L-talose. The aglycones are small phenols, isovaleric acid or aromatic carboxylic acids. By precursor-directed biosynthesis, the yields of the compounds could be increased significantly. Feeding of 4-hydroxybenzoic acid led to the production of both acyl and aryl glycosides, and of compound 9 with both structural elements. Pyrrol-2-ylcarbonyl 6-deoxy-alpha-L-talopyranoside (6) shows remarkable growth inhibition of some parasites. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006
Studies of precursor-directed biosynthesis with streptomyces, part 4. Novel alpha-L-rhamnopyranosides from a single strain of Streptomyces by supplement-induced biosynthetic steps
No full textVarious acyl and phenyl alpha-L-rhamnopyranosides were produced by Streptomyces griseoviridis (strain Tu 3634) in the presence of different supplements. Some of the added aromatic compounds underwent structural transformations prior to rhamnosylation (1, 3, 5, 8, 9). Especially remarkable was the formation of an indole (9) when 3,5-diaminobenzoic acid was added, Other precursors were not accepted by the strain, but did induce or enhance the biosynthesis of aromatic carboxylic acids from the shikimate pathway. These acids were then transformed into the acyl alpha-L-rhamnopyranosides 10-13. This can be seen as a new strategy of pathway engineering. With derivatives 4 and 14-17 we gained further in-sight into the substrate specificity of the rhamnosyltransferase, in particular concerning the competition for rhamnosylation between a carboxylic acid and a phenol or aliphatic hydroxyl group. All isolated metabolites were detected by chemical screening and characterized by spectroscopic methods. The biosynthetic abilities of the strain result in a remarkable structural diversity within the family Of alpha-L-rhamnopyranosides. The strain exemplifies the one strain/ many compounds (OSMAC) approach. ((C) Wiley-VCH Verlag GnibH, 69451 Weinheim, Germany, 2002)
Studies of precursor-directed biosynthesis with streptomyces, 3 - Structural diversity of 1-O-acyl alpha-L-rhamnopyranosides by precursor-directed biosynthesis with Streptomyces griseoviridis
No full textThe ability of Streptomyces griseoviridis (strain Tu 3634) to glycosylate various carboxylic acids with I-rhamnose was investigated by feeding mainly heteroaromatic and aromatic carboxylic acids to growing cultures. The special application of the precursor-directed biosynthesis (PDB) gave rise to a wide variety of acyl alpha-L-rhamnopyranosides as novel metabolites. The experiments resulted in furanyl, pyrrolyl, thienyl, indolyl, and pyridyl derivatives (1-8), the analogues 9-24 were generated by feeding fluoro-, hydroxy- or aminobenzoic acids or cinnamic acids. All results are discussed with respect to the substrate specificity of the corresponding enzyme system
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