New Polyketide and Sesquiterpenoid Derivatives from the Magellan Seamount‐Derived Fungus Penicillium rubens AS‐130

Rubenpolyketone A (1), a polyketide featuring a new carbon skeleton having cyclohexenone condensed with a methyl octenone chain and a new linear sesquiterpenoid, chermesiterpenoid D (2), together with seven known secondary metabolites (3–9) were isolated and identified from the Magellan Seamount‐derived fungus Penicillium rubens AS‐130. Their structures were determined based on detailed analysis of NMR and mass spectroscopic data and the absolute configurations of these two new compounds were elucidated by the combination of quantum mechanical (QM)‐NMR and time‐dependent density functional (TDDFT) ECD calculation approaches. Chermesiterpenoids B (3) and C (4) showed potent inhibitory activities against the aquatic pathogen Vibrio anguillarum with MIC values of 0.5 and 1 μg/mL, respectively, while chermesin F (6) exhibited activity against Escherichia coli with MIC value of 1 μg/mL.