Dibenzofurans from the marine sponge-derived ascomycete Super1F1-09

Three dibenzofurans hitherto undescribed from nature and one known butyrolactone were isolated from the extract of the ascomycete Super1F1-09 isolated from the Fijian marine sponge Acanthella cavernosa. The isolated compounds were identified as 3,9-dimethyldibenzo[b,d]furan-1,7-diol (1), 3-(hydroxymethyl)-9-methyldibenzo[b,d]furan-1,7-diol (2), 1,7-dihydroxy-9-methyldibenzo[b,d]furan-3-carboxylic acid (3), and the known butyrolactone I (4) using different NMR spectroscopic techniques and accurate mass spectrometric analysis. 1 was synthesized together with structurally related dibenzofurans 6-8. 1 and 4 had moderate antibacterial activity toward Mycobacterium marinum and Staphylococcus aureus, whereas 2 and 3 proved inactive. In addition, all compounds had moderate inhibitory properties against epidermal growth factor receptor tyrosine kinase.