Cytotoxic Naphtho- γ-pyrones from the Mangrove Endophytic Fungus Aspergillus tubingensis (GX1-5E).

Four new dimeric naphtho- γ-pyrones, named rubasperone D ( 1), rubasperone E ( 2), rubasperone F ( 3), and its atropisomer rubasperone G ( 4), together with four known monomeric naphtho- γ-pyrones, TMC 256 A1 ( 5), rubrofusarin B ( 6), fonsecin ( 7), and flavasperone ( 8), were isolated from the mangrove endophytic fungus Aspergillus tubingensis (GX1-5E) cultivated in solid rice medium. Their structures were elucidated by spectroscopic methods, including IR, 1D- and 2D-NMR, and MS. In the in vitro cytotoxicity assays, 5 displayed inhibitory activities against tumor cell lines of MCF-7, MDA-MB-435, Hep3B, Huh7, SNB19, and U87 MG with IC50 values between 19.92 and 47.98 μ M. Compounds 1, 6, and 8 also showed mild cytotoxic activity. [ABSTRACT FROM AUTHOR]