Diphenyl ethers and depsidones from the endophytic fungus Aspergillus unguis BCC54176

Abstract

Four new diphenyl ethers, aspergillusethers G−J (1–4), and one new depsidone, emeguisin D (7), together with eighteen known compounds have been isolated and characterized from the endophytic fungus Aspergillus unguis BCC54176. The chemical structures were established based on spectroscopic evidence in conjunction with a chemical transformation. Furthermore, the chemical structure of compound 7 was verified by single-crystal X-ray diffraction data. The isolated compounds were evaluated for biological activity. Compound 7, emeguisin C (10), and nidulin (14) showed antibacterial activity against Bacillus cereus with an equal MIC value of 1.56 μg/mL, while emeguisin A (8), nornidulin (13), 2-chlorounguinol (16), and aspergillusidone C (21) displayed anti-phytopathogenic activity against Colletotrichum acutatum with the equal MIC value of 3.13 μg/mL. Compound 7 was also active against Staphylococcus aureus with an MIC value of 1.56 μg/mL. However, none of the tested compounds had cytotoxicity against cancerous (MCF-7 and NCI–H187) and non-cancerous (Vero) cells.