Viridistratins A−C, Antimicrobial and Cytotoxic Benzo[j]fluoranthenes from Stromata of Annulohypoxylon viridistratum (Hypoxylaceae, Ascomycota)

During the course of our search for novel biologically active metabolites from tropical fungi, we are using chemotaxonomic and taxonomic methodology for the preselection of interesting materials. Recently, three previously undescribed benzo[j]fluoranthenes (1−3) together with the known derivatives truncatones A and C (4, 5) were isolated from the stromata of the recently described species Annulohypoxylon viridistratum collected in Thailand. Their chemical structures were elucidated by means of spectral methods, including nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HR-MS). The new compounds, for which we propose the trivial names viridistratins A−C, exhibited weak-to-moderate antimicrobial and cytotoxic activities in cell-based assays.