Secondary metabolites from the endophytic fungi Penicillium polonicum and Aspergillus fumigatus.

Two new compounds, rhodostegone (1) from endophytic fungus Penicillium polonicum and cyclo-(l-Val-l-Leu) (2) from Aspergillus fumigatus, together with six known diketopiperazines (3-8), were isolated. The structures of these compounds were characterized through a combination of extensive IR, MS, NMR, and CD analysis.