New isocoumarin derivatives and meroterpenoids from the marine sponge-associated fungus Aspergillus similanensis sp. nov. KUFA 0013

• Published in: Marine drugs Vol. 12; no. 10; pp. 5160 - 5173
• Main Authors: Prompanya, Chadaporn, Dethoup, Tida, Bessa, Lucinda J, Pinto, Madalena M M, Gales, Luís, Costa, Paulo M, Silva, Artur M S, Kijjoa, Anake
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 14.10.2014; MDPI
• Subjects: Animals; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Aspergillus; Aspergillus - chemistry; Aspergillus similanensis; Bacteria - drug effects; Biological Products - chemistry; Biological Products - pharmacology; Candida albicans; Candida albicans - drug effects; Candida albicans - metabolism; Carbon - metabolism; chevalones; Fungi - chemistry; isocoumarins; Isocoumarins - chemistry; Isocoumarins - pharmacology; Marine; meroditerpenes; Methicillin-Resistant Staphylococcus aureus - drug effects; Porifera - microbiology; pyripyropenes; similanpyrones; Staphylococcus aureus; Terpenes - chemistry; Terpenes - pharmacology
• ISSN: 1660-3397; 1660-3397
• DOI: 10.3390/md12105160

Two new isocoumarin derivatives, including a new 5-hydroxy-8-methyl-2H, 6H-pyrano[3,4-g]chromen-2,6-dione (1) and 6,8-dihydroxy-3,7-dimethylisocoumarin (2b), a new chevalone derivative, named chevalone E (3), and a new natural product pyripyropene S (6) were isolated together with 6, 8-dihydroxy-3-methylisocoumarin (2a), reticulol (2c), p-hydroxybenzaldehyde, chevalone B, chevalone C, S14-95 (4), and pyripyropene E (5) from the ethyl acetate extract of the undescribed marine sponge-associated fungus Aspergillus similanensis KUFA 0013. The structures of the new compounds were established based on 1D and 2D NMR spectral analysis, and in the case of compound 3, X-ray analysis was used to confirm its structure and the absolute configuration of its stereogenic carbons. Compounds 1, 2a-c and 3-6 were evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria, Candida albicans ATCC 10231, and multidrug-resistant isolates from the environment. Chevalone E (3) was found to show synergism with the antibiotic oxacillin against methicillin-resistant Staphylococcus aureus (MRSA).