Publications by authors named "Siegfried Draeger"

Two new dihydroisochromenes, named seimisochromenes A and B (1 and 2), were isolated from an endophytic fungus, Seimatosporium sp. The structures of seimisochromenes A and B have been determined from 1D ((1)H and (13)C NMR spectra) and 2D (COSY, HMQC, HMBC, and NOESY) NMR experiments.

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Phytochemical investigation of the endophytic fungus Coniothyrium sp. resulted in the isolation of a new phenoxyphenyl ether, named coniothyren (1), and two known compounds, coniol (2) and (+)-epoxydon (3). The structure of the new compound was elucidated by detailed spectroscopic analysis, namely, (1)H NMR, (13)C NMR, COSY, HMQC, HMBC, and HR-EI-MS.

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Four known hydroxyanthraquinones (1-4) together with four new derivatives having a tetralone moiety, namely coniothyrinones A-D (5-8), were isolated from the culture of Coniothyrium sp., an endophytic fungus isolated from Salsola oppostifolia from Gomera in the Canary Islands. The structures of the new compounds were elucidated by detailed spectroscopic analysis and comparison with reported data.

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Two polyketides, cryptosporiopsin A (1) and hydroxypropan-2',3'-diol orsellinate (3), and a natural cyclic pentapeptide (4), together with two known compounds were isolated from the culture of Cryptosporiopsis sp., an endophytic fungus from leaves and branches of Zanthoxylum leprieurii (Rutaceae). The structures of these metabolites were elucidated on the basis of their spectroscopic and spectrometric data.

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Two new acaranoic acids, named seimatoporic acid A and B (1, and 2), together with six known compounds, R-(-)-mellein (3), cis-4-hydroxymellein (4), trans-4-hydroxymellein (5), 4R-hydroxy-5-methylmellein (6), (-)-5-hydroxymethylmellein (7), and ergosterol (8) were isolated from an endophytic fungus, Seimatosporium sp, by a bioassay-guided procedure. The structures of the new compounds have been assigned from analysis of the 1H and 13C NMR spectra, DEPT, and by 2D COSY, HMQC, HMBC and NOESY experiments. A mixture of compounds 1 and 2 showed strong antifungal activity against Botrytis cinerea, Septoria tritici, and Pyricularia oryzae.

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From the endophytic fungus Phomosis sp., four known phomosines A-D (1-4) and three new phomosines H-J (5-7) have been isolated. The structures of the new compounds were determined on the basis of their spectroscopic data analysis (1H, 13C, 1H-1H COSY, HMQC, and HMBC NMR, as well as mass spectrometry).

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Phomosine K (1), a new phomosine derivative, has been isolated from Phomopsis sp., in addition to six known compounds: phomosine A (2), phenylalanine amide (3), 2-hydroxymethyl-4beta,5alpha,6beta-trihydroxycyclohex-2-en (4), (-)-phyllostine (5), (+)-epiepoxydon (6), and (+)-epoxydon monoacetate (7). Preliminary studies showed that compound 1 had strong antibacterial activity, while compounds 4-7 showed good antifungal, antibacterial, and algicidal properties, except compounds 4 and 6, which lacked antifungal activity.

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Four new pyrenocines, named pyrenocines J-M (1-4), were isolated from an endophytic fungus, Phomopsis sp, by a bioassay-guided method. The structures of the new compound have been assigned from ¹H and ¹³C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. Preliminary studied showed that compounds 1, 2 and 4 showed good antifungal, antibacterial, and algicidal properties, while compound 3 had good antibacterial and algicidal properties.

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Cytospolides F-Q (6-17) and decytospolides A and B (18 and 19), 14 unusual nonanolide derivatives, were isolated from Cytospora sp., an endophytic fungus from Ilex canariensis. The structures were elucidated by means of detailed spectroscopic analysis, chemical interconversion, and X-ray single crystal diffraction.

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Chromatographic purification of the extract of an endophytic fungal culture yielded depsitinuside (1), a new phenolic ester together with ergosterol (2) and (22E,24S)-24-methyl-5-α-cholesta-7,22-diene-3β,5,6β-triol (3). The structure of 1 was elucidated based on 1D, 2D NMR spectroscopy and high-resolution mass spectrometry, whereas the known compounds (2 and 3) were identified by (1)H NMR, mass spectrometry, and in comparison with the literature values. Compound 1 was evaluated for its enzyme inhibitory potential against acetylcholinesterase, butyrylcholinesterase and lipoxygenase, and was found inactive (10%-40% inhibition at a concentration of 2 mg/ml).

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Massarigenin A (1) and papyracillic acids A (2) and B (3) were isolated from the endophytic fungus Microsphaeropsis sp. Their structures were elucidated by multidimensional nuclear magnetic resonance spectroscopy; the structure of massarigenin A (1) was also confirmed by X-ray crystallography. The absolute configuration of massarigenin A (1) was established by means of circular dichroism (CD) spectroscopy and time-dependent density functional theory (TDDFT) calculations.

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Two new benzyl gamma-butyrolactone analogues, (R)-5-((S)-hydroxy(phenyl)-methyl)dihydrofuran-2(3H)-one (1) and its 6-acetate (2), and a new naphthalenone derivative (8), together with eight additional known aromatic derivatives, (S)-5-((S)-hydroxy(phenyl)-methyl)dihydrofuran-2(3H)-one (3), (S)-5-benzyl-dihydrofuran-2(3H)-one (4), 5-phenyl-4-oxopentanoic acid (5), gamma-oxo-benzenepentanoic acid methyl ester (6), 3-(2,5-dihydro-4-hydroxy-5-oxo-3-phenyl-2-furyl)propionic acid (7), (3R)-5-methylmellein (9), integracins A (10) and B (11) were isolated from Cytospora sp., an endophytic fungus isolated from Ilex canariensis from Gomera. The structures of these compounds were elucidated by detailed spectroscopic analysis, comparison with reported data, and chemical interconversion.

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Chemical investigation of the fungal strain Microdiplodia sp. isolated from the shrub Lycium intricatum led to the isolation of four new compounds: a hexahydroxanthone (2), a 2,3-dihydrochroman-4-one (3), a 7-oxoxanthone derivative (4), and a 1,4-oxazepan-7-one (5). The relative configurations of the new compounds were determined by intensive NMR investigations, notably NOESY experiments at different temperatures.

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The new (22E,24R)-3-acetoxy-19(10-->6)-abeo-ergosta-5,7,9,22-tetraen-3beta-ol (1) and the known (22E,24R)-19(10-->6)-abeo-ergosta-5,7,9,22-tetraen-3beta-ol (2), two interesting ergosteroids with rare aromatized ring B, together with seven known derivatives, namely (22E,24R)-ergosta-5,7,22-trien-3beta-ol (3), (22E,24R)-ergosta-4,7,22-trien-3-one (4), (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (5), (22E,24R)-5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol (6), (22E,24R)-ergosta-7,22-dien-3beta,5alpha,6beta-triol (7), (22E,24R)-6-acetoxy-ergosta-7,22-dien-3beta,5alpha,6beta-triol (8), and (22E,24R)-3,6-diacetoxy-ergosta-7,22-dien-3beta,5alpha,6beta-triol (9), were isolated from Colletotrichum sp., an endophytic fungus isolated from Ilex canariensis from Gomera. The structures of these compounds were elucidated by detailed spectroscopic analysis, comparison with reported data, and chemical interconversion.

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Seven new drimane sesquiterpenoids (1-3, 6-9), along with the known compounds deoxyuvidin B (4), strobilactone B (5), and RES-1149-2 (10), were obtained from cultures of the fungus Aspergillus ustus, which was isolated from the marine sponge Suberites domuncula. Their structures were established by means of spectroscopic analyses including one- and two-dimensional NMR spectroscopy and high-resolution MS. Compounds 6, 7, and 10 showed cytotoxic activity against a panel of tumor cell lines, including L5178Y, HeLa, and PC12 cells, with 7 being the most active (EC(50) against L5178Y cell line: 0.

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Three new metabolites, microsphaeropsones A-C (1-3) with a unique oxepino[2,3-b]chromen-6-one (ring-enlarged xanthone) skeleton, were isolated from the endophytic fungus Microsphaeropsis species, co-occurring with their putative biogenetic anthraquinoide precursors citreorosein (4) and emodin (5). From another Microsphaeropsis species, large amounts of fusidienol A (8 a), smaller amounts of emodin (5), the known aromatic xanthones 9 a and 9 b, the new 3,4-dihydrofusidienol A (8 b), and the new aromatic xanthone 9 c were isolated. The endophyte Seimatosporium species produced a new aromatic xanthone, seimatoxanthone A (10), and 3,4-dihydroglobosuxanthone A (12), closely related to alpha-diversolonic ester (13) from Microdiplodia sp.

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Three new isocoumarin derivatives ( 2- 4) were isolated together with monocerin ( 1) from Microdochium bolleyi, an endophytic fungus from Fagonia cretica, a herbaceous plant of the semiarid coastal regions of Gomera. Compounds 2 and 3 are both 12-oxo epimers of 1, and 4 is a ring-opened derivative of 1. The structures were elucidated by detailed spectroscopic analysis and comparison with reported data.

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Blennolides A-G (2-8), seven unusual chromanones, were isolated together with secalonic acid B (1) from Blennoria sp., an endophytic fungus from Carpobrotus edulis. This is the first reported isolation of the blennolides 2 and 3 (hemisecalonic acids B and E), the existence of which as the monomeric units of the dimeric secalonic acids had long been postulated.

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The filamentous fungi associated with healthy and decaying Fucus serratus thalli were studied over a 1-year period using isolation methods and molecular techniques such as 28S rRNA gene PCR-denaturing gradient gel electrophoresis (DGGE) and phylogenetic and real-time PCR analyses. The predominant DGGE bands obtained from healthy algal thalli belonged to the Lindra, Lulworthia, Engyodontium, Sigmoidea/Corollospora complex, and Emericellopsis/Acremonium-like ribotypes. In the culture-based analysis the incidence of recovery was highest for Sigmoidea marina isolates.

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Three new massarilactones E-G (1-3) and the massarilactone acetonide (4) were isolated from the ethyl acetate extract of the endophytic fungus Coniothyrium sp., associated with the plant Artimisia maritima. Their structures were determined by analysis of the 1D and 2D NMR and mass spectroscopic data.

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The composition and relative abundance of endophytic fungi in roots of field-grown transgenic T4-lysozyme producing potatoes and the parental line were assessed by classical isolation from root segments and cultivation-independent techniques to test the hypothesis that endophytic fungi are affected by T4-lysozyme. Fungi were isolated from the majority of root segments of both lines and at least 63 morphological groups were obtained with Verticillium dahliae, Cylindrocarpon destructans, Colletotrichum coccodes and Plectosporium tabacinum as the most frequently isolated species. Dominant bands in the fungal fingerprints obtained by denaturing gradient gel electrophoresis analysis of 18S rRNA gene fragments amplified from total community DNA corresponded to the electrophoretic mobility of the 18S rRNA gene fragments of the three most abundant fungal isolates, V.

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Aspochalamins A-D, a family of new cytochalasan antibiotics have been isolated from Aspergillus niveus, an endosymbiotic fungus isolated from the gut of a woodlouse belonging to the family Trichoniscidae. Besides aspochalamins, aspochalasin Z, a new member of the aspochalasin family, as well as the known mycotoxins aspochalasin D and citreoviridins A/C and B were isolated from the mycelium. Aspochalamins showed cytostatic effects towards various tumor cell lines and a weak antibacterial activity against Gram-positive bacteria.

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Six known metabolites, two new isocoumarins 4 and 8, and one new highly substituted benzoic acid derivative 9 were isolated from the ethyl acetate culture extract of a fungal endophyte, Scytalidium sp. In addition, another new benzoic acid 10 with an unusual 1,2-dicarbonyl side chain was indirectly identified from its methylated derivatives 10a-10d.

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8-alpha-Acetoxyverrol (4), the first open chain example of the trichothecenes with oxygenation at C-8, was isolated from cultures of Aphanocladium spectabile. The compound doses the biosynthetic gap to the macrocyclic verrucarins.

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