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 IC(50) values ranging from 10.45 to 30.42 μM.