New Isocoumarin Derivatives and Meroterpenoids from the Marine Sponge-Associated Fungus Aspergillus similanensis sp nov KUFA 0013


Prompanya, C (Prompanya, Chadaporn)[ 1,2 ] ; Dethoup, T (Dethoup, Tida)[ 3 ] ; Bessa, LJ (Bessa, Lucinda J.)[ 1,2 ] ; Pinto, MMM (Pinto, Madalena M. M.)[ 2,4,5 ] ; Gales, L (Gales, Luis)[ 1,6 ] ; Costa, PM (Costa, Paulo M.)[ 1,2 ] ; Silva, AMS (Silva, Artur M. S.)[ 7,8 ] ; Kijjoa, A (Kijjoa, Anake)[ 1,2 ]
Mar. Drugs 2014, 12, 5160-5173


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).