Cytotoxic Secondary Metabolites from the Ascomycetous Fungus Pseudogymnoascus roseus

Background: Fungi found in unique and competitive environments are abundant in bioactive compounds. Objective: The objective of this study is to isolate and identify secondary metabolites from fungi of unique ecological niches and evaluate their cytotoxicity. Methods: The compounds were isolated and purified using silica gel column chromatography, Sephadex LH-20 gel chromatography, and semi-preparative high-performance liquid chromatography (HPLC). The structures of the isolated compounds were determined using NMR and MS. The cytotoxic activities of these compounds were tested by the MTS assay. Results: Three diphenyl ethers, dechlorodihydromaldoxin (1), violaceol-I (2) and violaceol-II (3), one quinolinone compound, 2-(2-heptenyl)-3-methyl-4(1H)-quinolinone (4), and one α-pyrone nafuredin (5) were isolated from the fermented extracts of Pseudogymnoascus roseus S161. Compound 1 showed modest cytotoxicity against two human tumor cell lines A549 and MCF-7, with IC50 values of 87.12 and 51.07 µM, respectively. Conclusion: Five compounds were isolated from the fungus P. roseus S161. Compound 1 showed moderate cytotoxicity. This study provided a basis for the development of antitumor drugs.