Neoplaether, a new cytotoxic and antifungal endophyte metabolite from Neoplaconema napellum IFB-E016

A new diphenyl ether, named neoplaether, together with five known compounds monomethylsulochrin, physcion, helvolic acid, ergosterol and ergosterol peroxide, was isolated from the culture of Neoplaconema napellum IFB-E016, an endophytic fungus residing in the healthy leaves of Hopea hainanensis. The structure of neoplaether was elucidated by a correlative interpretation of its infrared spectrometry, mass spectroscopy and nuclear magnetic resonance spectra, and confirmed by its single-crystal X-ray diffraction analysis. Neoplaether exhibited significant cytotoxic activity against the human nasopharyngeal epidermoid tumor KB cell line, with an IC(50) value of 13.0 microg mL(-1), comparable to that of 5-fluorouracil (2.5 microg mL(-1)) co-assayed as a positive reference. In addition, it showed antifungal activity against Candida albicans, with a minimal inhibitory concentration value of 6.2 microg mL(-1) (amphotericin as a positive control had a value of 1.5 microg mL(-1)).