Discovery of MK8383s with Antifungal Activity from Mangrove Endophytic Fungi Medicopsis sp. SCSIO 40440 Against Fusarium Wilt of Banana

Fusarium wilt of banana (FWB), caused by <i>Fusarium oxysporum</i> f. sp. <i>cubense</i> (<i>Foc</i>) tropical race 4 (TR4), poses a severe threat to the global banana industry. The screening of endophytic fungi from the mangrove plant led to the identification of <i>Medicopsis</i> sp. SCSIO 40440, which exhibited potent antifungal activity against Fusarium. The further fraction of the extract yielded ten compounds, including MK8383 (<b>1</b>) and nine new analogues, MK8383s B-J (<b>2</b>-<b>10</b>). The structures of <b>1</b>-<b>10</b> were elucidated using extensive spectroscopic data and single-crystal X-ray diffraction analysis. In vitro antifungal assays revealed that <b>1</b> showed strongly antifungal activities against Foc TR4, with an EC₅₀ of 0.28 μg/mL, surpassing nystatin and hygromycin B (32 and 16 μg/mL, respectively). Pot experiments showed that <b>1</b> or spores of SCSIO 40440 could significantly reduce the virulence of <i>Foc</i> TR4 on Cavendish banana.