Amichalasines A–C: Three Cytochalasan Heterotrimers from Aspergillus micronesiensis PG-1

Amichalasines A–C (1–3), which represent a new type of cytochalasan heterotrimers, were isolated from Aspergillus micronesiensis PG-1. Compounds 1 and 2 possess an undecacyclic 5/6/11/5/5/6/6/5/11/6/5 ring system, and 3 has an additional furan ring with a dodecacyclic 5/6/11/5/5/6/6/5/5/11/6/5 ring system. 1 and 2 exhibited potent cytotoxic activities through apoptosis induction mediated by caspase-3 activation and PARP degradation, and their IC50 values against HL60 cells were 1.71 and 3.74 μM, respectively.