Cytotoxic Nitrogenated Azaphilones from the Deep-Sea-Derived Fungus Chaetomium globosum MP4-S01‑7

Eight new nitrogenated azaphilones (1–8) and two known compounds (chaetoviridin A and chaetoviridin E, 9, 10) were isolated from the culture of the deep-sea-derived fungus Chaetomium globosum MP4-S01-7. The absolute configurations of new compounds were elucidated by HSQC-HECADE NMR data, J-based configuration analysis, and modified Mosher’s method and finally verified by comparison of recorded and computed NMR chemical shifts from quantum chemical calculations coupled with a statistical procedure (DP4+). All of the compounds were evaluated for their in vitro cytotoxicities against the gastric cancer cell lines MGC803 and AGS, and most of them showed significant inhibition on cancer cell viability at 10 μM. Among them, compounds 1, 2, and 5 exerted the most potent cytotoxic activities, with IC50 values less than 1 μM. Further studies showed that compound 2 inhibited cell cycle progression, and both compounds 1 and 2 induced apoptosis of gastric cancer cells in a concentration-dependent manner.