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  • Analytical Chemistry and Spectroscopy  (1)
  • Polyketides  (1)
  • 1
    ISSN: 1434-193X
    Keywords: Marine fungi ; Tyrosine kinase ; Natural products ; Macrodiolides ; Polyketides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sponge-derived fungi Ulocladium botrytis and Asteromyces cruciatus, and the algal-derived fungus Varicosporina ramulosa, were isolated and extracts from cultures investigated for their metabolite production. Investigations of the extract of the culture of U. botrytis guided by bioassay yielded the new tyrosine kinase (p56lck) inhibitor ulocladol (1) together with 1-hydroxy-6-methyl-8-(hydroxymethyl)xanthone (3), which showed antifungal activity. The extract of the culture medium of A. cruciatus yielded the new metabolite (+)-2,4-dimethyl-4,5-dihydrofuran-3-carbaldehyde (4) together with the known compounds (3S,5R)-dimethyldihydrofuran-2-one (5) and tri-O-acetyl glycerol. From V. ramulosa the five macrodiolides grahamimycin A1 (6), colletoketol (7), (6R,11R,12R,14R)-colletodiol (8), 9,10-dihydro-(6R,11S,12S,14R)-colletodiol (9) and 9,10-dihydro-(6R,11R,12R,14R)-colletodiol (10) together with ergosterol were obtained, 9 and 10 being new fungal metabolites.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0749-1581
    Keywords: 1H NMR ; 13C NMR ; NOESY ; INADEQUATE ; lanthanide shift reagents ; brown algae ; sesquiterpenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From the marine brown alga Dictyopteris delicatula Lamaouroux, two new (1, 3) and two previously reported sesquiterpenes (2, 4) were isolated and characterized. Compound 1 was identified as 4β,5α-dihydroxycubenol and 2 was found to be a non-racemic mixture of (±)-torreyol. Compound 3 was characterized as cubenol-3-one and 4 was identified as cubenol. For the assignment of the complete relative stereochemistry of compounds 1 and 2, it was necessary to employ extensive 2D NMR methodologies in combination with the lanthanide shift reagent europium(III) tris(1,1,1,2,2,3,3)-heptafluoro-7,7-dimethyl-d6-octane-4,6-dione-d3 [Eu(fod)3]. Anomalous proton shielding effects which occurred on addition of Eu(fod)3 to compound 1 suggested that classical lanthanide-induced shift (LIS) analysis for predicting proton chemical shifts was not applicable. Application of 2D NOESY measurements to NMR samples of 1 and 2 containing Eu(fod)3 clearly demonstrated an alternative to classical methods for interpreting lanthanide-induced shifts. The enhanced value of shift reagnents of this type as an aid to structure determination and as for assignment purposes is demonstrated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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