Spectasterols, Aromatic Ergosterols with 6/6/6/5/5, 6/6/6/6, and 6/6/6/5 Ring Systems from Aspergillus spectabilis

Spectasterols A–E (1–5), aromatic ergosterols with unique ring systems, were isolated from Aspergillus spectabilis. Compounds 1 and 2 possess a 6/6/6/5/5 ring system with an additional cyclopentene, while 3 and 4 have an uncommon 6/6/6/6 ring system generated by the D-ring expansion via 1,2-alkyl shifts. Compound 3 exhibited cytotoxic activity (IC50 6.9 μM) and induced cell cycle arrest and apoptosis in HL60 cells. Compound 3 was anti-inflammatory; it decreased COX-2 levels at the transcription and protein levels and inhibited the nuclear translocation of NF-κB p65.