Cytotoxic Chaetoglobosins From a Soil‐derived <i>Chaetomium</i> sp.

Ten chaetoglobosin alkaloids were isolated from the fermentation culture of a soil-derived fungus, Chaetomium sp., and their structures with absolute configurations were characterized by spectroscopic methods including high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), X-ray diffraction analysis, and electronic circular dichroism, as well as comparison with literature data. Among them, three compounds (1-3) have not been described previously, and compound 8 is reported for the first time as a new natural product. A preliminary cytostatic screening revealed good inhibitory activity for 1, 6, and 8 against the A549 cell line (lung), and for 1, 2, 4, 6, and 8 against the MDA-MB231 cell line (breast). Further exploration demonstrated that compound 8 exerted in vitro antitumor activity by inducing significant apoptosis and S-phase cycle arrest, as well as blocking the migration and invasion of MDA-MB231 cells.