Antimicrobial Polyketides from the Marine-Derived Fungus sp. SCSIO F190.

Three diphenyl ethers (-) and a cyclopentenone (), together with seven known compounds (-), were isolated from the fermentation broth of the marine sediment-derived fungus sp. SCSIO F190. Compounds and were found to exist as a pair of atropisomers (, ) and racemates (, ), respectively. The planar structures of compounds - were elucidated on the basis of NMR and HRESIMS data sets. The absolute configurations of and were determined by spectroscopic and single-crystal X-ray diffraction analyses, whereas the configuration of was determined by spectroscopic and chiral analyses. All compounds, except for and , displayed activities against various pathogenic bacteria. Notably, compounds -, especially , exhibited strong activity against Gram-positive bacteria, including methicillin-resistant bacterial strains of (MRSA), ATCC 29212, and BS01, with MIC values ranging from 0.5 to 4 μg/mL. Moreover, the structure-activity relationship analyses of the active compounds and their analogues revealed the critical structural features correlating to the observed antimicrobial activities, herein providing insights for antimicrobial drug development.