Nine new cytochalasan alkaloids from Chaetomium globosum TW1-1 (Ascomycota, Sordariales)

Chemical investigation on the methanol extract of Chaetomium globosum TW1-1, a fungus isolated from the common pillbug (Armadillidium vulgare), has resulted in the isolation of nine new highly oxygenated cytochalasan alkaloids, armochaetoglobins S-Z (1 and 3-9) and 7-O-acetylarmochaetoglobin S (2), together with eight structurally related known analogues (10-17). Their structures and absolute configurations were elucidated by spectroscopic analyses. Among them, compound 2 presents to be the first member of chaetoglobosin family with an acetyl group, and compounds 3 represents the first chaetoglobosin characterized by an 2',3'-epoxy-indole moiety. The discovery of these new compounds revealed the largely untapped chemical diversity of cytochalasans and enriched their chemical research. Compounds 1-9 were evaluated for their cytotoxic activities against five human cancer cell lines, and compounds 8 and 9 exhibited significant cytotoxic activities with IC50 values ranging from 10.45 to 30.42 μM.