Chaephilones A and B, Two New Azaphilone Derivatives Isolated from Chaetomium globosum

Two new azaphilone derivatives, chaephilones A (1) and B (2), were isolated from the fungus Chaetomium globosum, together with four structurally related analogs 3 – 6. The structures of 1 and 2 were elucidated by comprehensive spectroscopic analyses including HR‐ESI‐MS and NMR. The known compounds were identified as chaetomugilin Q (3), chaetomugilin D (4), 11‐epichaetomugilin A (5), and chaetomugilin S (6) by comparing their NMR data and optical rotation values with those reported. Compound 2 represents the first example of azaphilone with an open furan ring. Compounds 1 and 2 were evaluated for cytotoxic activities against five human cancer cell lines (HL‐60, SMMC‐7721, A‐549, MCF‐7, and SW480) by the MTS method.