Comparison of the Secondary Metabolism of the Basidiomycetes Armillaria mellea and Desarmillaria ectypa.

During the course of our ongoing studies on the secondary metabolism of cultures of Basidiomycota, a new meroterpenoid named 10, 15-dihydroxydihydromelleolide (1) was isolated along with the known armillaridin (2) and arnamiol (3) from cultures of the rare saprotrophic species, Desarmillaria ectypa. These are the first secondary metabolites that were ever isolated from the latter species. A concurrently studied strain of the common pathogenic A. mellea yielded other melleolides, with 5'-O-methylmelledonal (4), melledonal C (5), 10 α-hydroxydihydromelleolide (6) and melledonal (7). The chemical structures were elucidated using 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). All compounds were studied for their antimicrobial and cytotoxic effects against a panel of microbes and mammalian cell lines, and the results are also reported.