Sucurchalasins A and B, Sulfur-Containing Heterodimers of a Cytochalasan and a Macrolide from the Endophytic Fungus Aspergillus spelaeus GDGJ-286

Two sulfur-containing heterodimers of a cytochalasan and a Macrolide, sucurchalasins A and B (1 and 2), and four known cytochalasan monomers (3-6), as well as four known Macrolide derivatives (7-10), were obtained from the endophytic fungus Aspergillus spelaeus GDGJ-286. Sucurchalasins A and B (1 and 2) are the first cytochalasan heterodimers formed via a thioether bridge between cytochalasan and curvularin Macrolide units. Their structures were elucidated by detailed analysis of NMR, LC-MS/MS, and X-ray crystallography. In bioassays, 1 and 2 exhibited cytotoxic effects on A2780 cells, with IC₅₀ values of 3.9 and 8.3 μM, respectively. They also showed Antibacterial activities against E. faecalis and B. subtilis with MIC values of 3.1 and 6.3 μg/mL, respectively.