Protoilludene and Alkenoic Acid Derivatives from the European Polypore Fomitiporia hartigii

Chemical investigation of the solid-state rice culture of the endangered European polypore Fomitiporia hartigii (Hymenochaetaceae) afforded a previously undescribed protoilludene derivative (1) in addition to six known compounds (2-7). Chemical structures of the isolated compounds were established based on HR-ESI-MS, comprehensive 1D/2D NMR spectroscopic analyses, and comparisons with the literature. All isolated compounds were assessed for their cytotoxic and antimicrobial activities. Among the tested compounds, hymeglusin (3) revealed potent cytotoxic activity against all tested cell lines with IC₅₀ values between 0.3 and 6.8 μM. Compound 3 and fusaridioic acid A (4) revealed weak to moderate antimicrobial activities with its most potent effect against Candida albicans (minimum inhibitory concentration of 4.2 μg/mL).