(±)-Brevianamides Z and Z1, New Diketopiperazine alkaloids from the marine-derived fungus Aspergillus versicolor

(±)-brevianamide Z [(±)-1] and (±)-brevianamide Z1 [(±)-2], two new pairs of diketopiperazine alkaloids, along with nine known analogues [(±)-3, (±)-4, (±)-5, 6, 7, and 8], were isolated from the marine-derived fungus Aspergillus versicolor. The structures of 1–8 including their absolute configurations were assigned based on extensive spectroscopic analysis, and calculated NMR, ECD, ORD and DP4+ methods. All the obtained compounds were evaluated for their cytotoxic, antibacterial, and antifungal activities. Among them, 7 exhibited potent cytotoxic activity against the HGC-27 cell line with an IC50 value of 4.54 µM, stronger than that of cisplatin (IC50, 8.63 µM).