Thiersinines A and B: novel antiinsectan indole diterpenoids from a new fungicolous Penicillium species (NRRL 28147).

[structure: see text] Two novel antiinsectan indole diterpenoids, thiersinines A (1) and B (2), along with seven known paxilline-type compounds, were isolated from organic extracts of a new Penicillium species (P. thiersii NRRL 28147). The structures of 1 and 2 were determined by analysis of 2D NMR data. Thiersinines A and B possess a unique spirocyclic subunit that is unprecedented in previously known compounds of this class. Both compounds exhibit potent activity against the fall armyworm (Spodoptera frugiperda).