Depsidones, Aromatase Inhibitors and Radical Scavenging Agents from the Marine-Derived Fungus Aspergillus unguis CRI282-03

Three new depsidones (1, 3, and 4), a new diaryl ether (5), and a new natural pyrone (9) (synthetically known), together with three known depsidones, nidulin (6), nornidulin (7), and 2-chlorounguinol (8), were isolated from the marine-derived fungus Aspergillus unguis CRI282-03. Aspergillusidone C (4) showed the most potent aromatase inhibitory activity with the IC50 value of 0.74 mu M, while depsidones 1, 3, 6-8 inhibited aromatase with IC50 values of 1.2-11.2 mu M. It was found that the structural feature of depsidones, not their corresponding diaryl ether derivatives (e. g. 5), was important for aromatase inhibitory activity. Aspergillusidones A (1) and B (3) showed radical scavenging activity in the XXO assay with IC50 values of 16.0 and < 15.6 mu M, respectively. Compounds 1 and 3-7 were mostly inactive or showed only weak cytotoxic activity against HuC-CA-1, HepG2, A549, and MOLT-3 cancer cell lines.