Bioactive Polyketides From the Mangrove Endophytic Fungus Cytospora Rhizophorae SCNU‐F0054

Mangrove endophytic fungi are recognized as a prolific source of structurally unique and bioactive secondary metabolites. In this study, we aimed to investigate the chemical diversity and biological potential of the mangrove‐derived fungus Cytospora rhizophorae SCNU‐F0054, leading to the isolation of four new polyketides, namely (14 R , 15' R )‐integracin D ( 1 ), cytospyrone B ( 8 ), furanone 2 ( 12 ), 4‐ethyl‐2‐hydroxy‐2,5‐dimethylcyclopent‐4‐ene‐1,3‐dione ( 14 ), together with ten known analogues. Their structures were elucidated based on extensive spectroscopic analyses, TDDFT‐ECD calculations, and comparisons of experimental ECD spectra. In antibacterial assays, compound 7 exhibited potent, broad‐spectrum activity against all tested strains, with MIC ranging from 1.56 to 6.25 µ g/mL. Among the dimeric alkylresorcinols, the sulfated derivative 1 was most active against S. aureus and E. coli . In α ‐glucosidase inhibitory assay, alkylresorcinols 1 , 2 , 4 , and 5 outperformed the positive control (1‐deoxynojirimycin), with IC 50 values of 3.53−12.35 µ M. Overall, the alkylresorcinol subclass demonstrated stronger antibacterial and enzyme inhibitory activities than the other polyketides in this study, highlighting their potential as promising lead compounds for further pharmaceutical development.