New Diketopiperazines from a Marine-Derived Fungus Strain Aspergillus versicolor MF180151

Six new diketopiperazines, (+/-)-7,8-epoxy-brevianamide Q ((+/-)-1), (+/-)-8-hydroxy-brevianamide R ((+/-)-2), and (+/-)-8-epihydroxy-brevianamide R ((+/-)-3), together with four known compounds, (+/-)-brevianamide R ((+/-)-4), versicolorin B (5) and averufin (6), were isolated from a marine-derived fungus strain Aspergillus versicolor MF180151, which was recovered from a sediment sample collected from the Bohai Sea, China. The chemical structures were established by 1D- and 2D-NMR spectra and HR-ESI-MS. 1 is the first sample of brevianamides with an epoxy moiety. Their bioactivities were evaluated against Candida albicans, Bacillus subtilis, Staphylococcus aureus, methicillin-resistant S. aureus, Pseudomonas aeruginosa, and Bacillus Calmette-Guerin. Compounds 1-4 showed no activities against the pathogens, and compounds 5 and 6 showed moderate activities against S. aureus and methicillin-resistant S. aureus.