Spectaterpenoids A–G, Sesterterpenoids with Unprecedented Polycyclic Ring System from <i>Aspergillus spectabilis</i>

Spectaterpenoids A–G ( 1 – 7 ), seven novel sesterterpenoids with five distinct skeleton types, along with one known analogue ( 8 ), were characterized from Aspergillus spectabilis . Notably, compound 1 was a nitrogenous sesterterpenoid possessing an unprecedented 5/3/8/6/5-fused pentacyclic system, while compounds 2 and 3 feature a novel 5/5/8/6/6/5-fused hexacyclic scaffold. Compounds 4 and 5 represent the first examples possessing a five-membered lactam bridge connecting C-5 and C-20 in variecolin derivatives. Plausible biosynthetic pathways for 1 – 8 were proposed.