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Aspercitrininone A (1), a novel polyketide featuring an unprecedented tetracyclic 6/6/6/5 spiral skeleton, was obtained from the rice fermentation cultures of the fungus Aspergillus cristatus together with five known compounds (2 – 6). Their structures were determined by HRESIMS data, 1D and 2D NMR spectroscopic analysis, and electronic circular dichroism (ECD) calculations. Aspercitrininone A was revealed as a new type of C/D cycle spiral structure and an unusual addition product of o-quinoid form citrinin with 2-methylterrefuranone. Compounds 1 , 4 , and 5 exhibited potent antibacterial activities with minimal inhibitory concentration (MIC) values from 13.2 to 67.3 μg/mL against four strains of human pathogenic bacteria in vitro. [Display omitted] • A novel polyketide aspercitrininone A was isolated from rice cultures of Aspergillus cristatus. • Aspercitrininone A possessed an unprecedented tetracyclic 6/6/6/5 spiral skeleton. • It could be formed by o-quinoid form citrinin with 2-methylterrefuranone through Michael addition reaction. • Aspercitrininone A exhibited antibacterial activities. [ABSTRACT FROM AUTHOR]

Two novel fungal polyketides, phometides A (1) and B (2), together with four known compounds (3–6), were isolated from the endophytic fungus Phoma sp. YUD17001 obtained from Gastrodia elata Blume. The structures were elucidated based on spectroscopic analyses, X-ray crystal diffraction, and time-dependent density functional theory/electronic circular dichroism (TDDFT/ECD) calculations. Structurally, phometide A (1) represented the first example of C 12 polyketide characterized by an unusual tetrahydrobenzofuran-3(2 H)-one core with an α , β -unsaturated ketone functionality, while phometide B (2) was an unprecedented molecule containing a 2-pentylcycloheptan-1-one scaffold. In an antimicrobial activity assay, phometide A (1) exhibited significant inhibitory activity against Staphylococcus aureus with MIC value of 4 μg/mL. Phometide B (2) showed moderate antifungal activity against Candida albicans with an MIC value of 16 μg/mL. Furthermore, compounds 1 and 2 were evaluated for their acetylcholinesterase inhibitory and cytotoxic activities. [Display omitted] • Two novel fungal polyketides were identified from the endophytic fungus Phoma sp. YUD17001. • Phometide A possess an unusual tetrahydrobenzofuran-3(2 H)-one functionality. • Phometide B is a novel polyketone containing a 2-pentylcycloheptan-1-one scaffold. • Phometides A and B demonstrated antimicrobial activity against S. aureus and C. albicans , respectively. [ABSTRACT FROM AUTHOR]