Unusual chaetoglobosins and a new type of ferroptosis inducer from an endophytic fungus Chaetomium sp. UJN-EF006

Seven unreported chaetoglobosin-type alkaloids, namely brachaetoglobosin A ( 1 ), chaetochalasins B F ( 2 – 6 ) and armochaeglobine C ( 7 ), together with the formerly described cytoglobosin C ( 8 ) and chaetoglobosin E ( 9 ), were obtained from an endophytic fungus Chaetomium sp. UJN-EF006 isolated from the leaves of Vaccinium bracteatum . Their structures were characterized through various spectral techniques including MS, NMR, X-ray crystallography and electronic circular dichroism. Also, this is only the second record of novel chaetochalasin and armochaeglobine skeletons of the cytochalasin super family, after 27 and 10 years of the first report, respectively. Compound 9 showed significant cytotoxic effect against two human tumor cell lines (MDA-MB231 and A549) and was identified as a new type of ferroptosis inducer (toward A549 cells) that could be used as a molecular tool in future related research.