A New Tyrosine Kinase Inhibitor from a Marine Isolate ofUlocladium botrytis and New Metabolites from the Marine FungiAsteromyces cruciatus andVaricosporina ramulosa

Abstract

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.