Fractionation of the methanol extract of the fruit bodies of the xylariaceus ascomycete Hypoxylon rubiginosum resulted in the isolation of three new azaphilone derivatives named rubiginosins A-C (1-3) and a new fatty acid named rubiginosic acid (4), together with three known compounds, entonaemin A (5), daldinin C (6), and orsellinic acid. Their structures were elucidated by 2D NMR, MS, IR, and UV spectra and chemical reaction. The absolute configuration of compound 3 was established by CD spectroscopy. The structure of 4 was confirmed by X-ray crystallographic analysis.
