Cytotoxic and Antibacterial Compounds from the Coral-Derived Fungus Aspergillus tritici SP2-8-1

Three novel compounds, 4-methyl-candidusin A (1), aspetritone A (2) and aspetritone B (3), were obtained from the culture of a coral-derived fungus Aspergillus tritici SP2-8-1, together with fifteen known compounds (4-18). Their structures, including absolute configurations, were assigned based on NMR, MS, and time-dependent density functional theory (TD-DFT) ECD calculations. Compounds 2 and 5 exhibited better activities against methicillin-resistant strains of S. aureus (MRSA) ATCC 43300 and MRSA CGMCC 1.12409 than the positive control chloramphenicol. Compound 5 displayed stronger anti-MRSA and lower cytotoxic activities than 2, and showed stronger antibacterial activities against strains of Vibrio vulnificus, Vibrio rotiferianus, and Vibrio campbellii than the other compounds. Compounds 2 and 10 exhibited significantly stronger cytotoxic activities against human cancer cell lines HeLa, A549, and Hep G2 than the other compounds. Preliminary structure-activity relationship studies indicated that prenylation of terphenyllin or candidusin and the tetrahydrobenzene moiety in anthraquinone derivatives may influence their bioactivity.