New tetrahydroanthraquinones and γ-butenolides from the fungus Auxarthron umbrinum DSM3193

Nine new compounds including seven tetrahydroanthraquinones (auxarthrolones A-G, 1-7), a γ-butenolide glycoside (malfilamentoside E, 26), and a γ-butenolide (auxarthrolide A, 27), along with eighteen known compounds (8-25) were identified from rice-based solid culture of Auxarthron umbrinum DSM3193 by the one strain many compounds (OSMAC) strategy. The structures of these compounds were elucidated by NMR, MS, and NMR calculation as well as DP4 + analysis or MAE_ΔΔδ parameter, and the absolute configurations of new compounds were determined by single-crystal X-ray diffraction, electronic circular dichroism (ECD) spectroscopic data analysis and/or chemical derivatization. Austrocortilutein (10) and auxarthrol H (14) exhibited moderate cytotoxicity against U87 and U251 (IC₅₀: 3.5-12.1 μM). While auxarthrolone A (1), auxarthrol H (14), eupolyphagin B (15), and 7-hydroxy-2-(2-hydroxypropyl)-5-methylchromone (17) showed torsional effects on fibroblast proliferation difficulties caused by oleic acid, thereby exhibited the activity of promoting fibroblast proliferation.