Nuclear Magnetic Resonance Screening Approach for Discovery of 5‐Hydroxymethylfurfural Derivatives from Marine Fungus <i>Fusarium oxysporum</i> SP7

By tracing the characteristic proton and carbon nuclear magnetic resonance signals of the furan ring and aldehyde group, four novel 5-hydroxymethylfurfural derivatives, fusaroxysporins A-D (1-4), together with 10 known compounds were obtained from the marine fungus Fusarium oxysporum SP7. Their structures were elucidated by comprehensive spectroscopic analysis. The possible biogenic synthesis pathways of these compounds were speculated. Compound 1 showed moderate cytotoxic activity against the human type II alveolar epithelial cell A-549 and the human hepatocarcinoma cell line HepG2 with IC₅₀ values of 48.0 and 92.0 µM, respectively, while the other compounds had no activity (IC₅₀ > 200 µM).