Antimicrobial Dolabellanes and Atranones from a Marine-Derived Strain of the Toxigenic Fungus .

Three new dolabellane-type diterpenoids (-) and three new atranones (-) were isolated and identified from a marine-derived strain of the toxigenic fungus . The planar and relative structures of - were elucidated using extensive spectroscopic methods, and their absolute configurations were fully confirmed via single-crystal X-ray diffraction analysis. Structurally, compounds and have a 1,14- dolabellane-type diterpenoid skeleton; compound is the first C atranone featuring a propan-2-one motif linked to a dolabellane-type diterpenoid by a carbon-carbon bond; compound represents the first example of a C atranone with a 2-methyltetrahydrofuran-3-carboxylate motif fused to a dolabellane-type diterpenoid at C-5-C-6. In an in vitro antimicrobial activity assay, compound was active against and with MIC values of 16 and 32 μg/mL, respectively, while compound exhibited significant inhibitory activities against , , and methicillin-resistant (MRSA) with MIC values of 8, 16, and 32 μg/mL, respectively.