Studies on fungal products. Part 10. Isolation and structures of novel bicoumarins, desertorins A, B, and C, from Emericella desertorum
Together with silvaticol (11), nidulol (12), ergosterol, paxilline (10), and mannitol, three new bicoumarins designated as desertorin A (1)(C22H18O8), B (2)(C23H20O8), and C (3)(C26H22O8) have been isolated from Emericella desertorum, strain CBS 653.73. The structures of desertorins A (1), B (2), and C (3) were determined on the basis of the spectroscopic and chemical investigations of these compounds and their derivatives i.e., as 7,7′-dihydroxy-4,4′-dimethoxy-5,5′-dimethyl-6,8′-bicoumarin, 5,5′-dimethyl-6,8′-bicoumarin, 5,5′-dimethyl-7-hydroxy-4,4′,7′-trimethoxy-6,8′-bicoumarin and 5,5′-dimethyl-4,4′,7,7′-tetramethoxy-6,8′-bicoumarin, respectively. It is interesting to note that silvaticol (11) and nidulol (12), both of the known metabolites of Aspergillus silvaticus, were isolated from the same extracts.