Indole Diketopiperazine Alkaloids Isolated From the Marine-Derived Fungus Aspergillus chevalieri MCCC M23426

Two new indole diketopiperazines (1-2) obtained from the fermentation culture of a deep-sea-derived fungus Aspergillus chevalieri MCCC M23426, were characterized, together with nine biogenetic related compounds (3-11). The structures of 1-2 were assigned based on NMR, MS, NMR calculation, DP4+ analysis, and ECD calculation. The bioactive assay showed that compounds 1, 5-7 significantly inhibited the growth of Staphylococcus aureus. Meanwhile, compound 8 potently reduced the cell viability of gastric cancer cell MKN1 with an IC50 value of 4.6 mu M.