| Interspecies competition (antagonism) is thought to play an important role in the pattern of colonization within fungal ecosystems. Such competitive interactions among fungi can be useful in the selection of species for chemical investigation in search of new bioactive natural products. Certain types of coprophilous (dung-colonizing) fungi have been observed to display antagonistic activity against competing fungal species. Previous bioassay-guided studies conducted by our group have led to the isolation of a variety of new metabolites with activity against competitor fungi and the medically relevant yeast, Candida albicans. As part of this ongoing project, ethyl acetate extracts from cultures of Ascodesmis sphaerospora, Sporormiella pilosa, Preussia fimicola, and Bombardioidea anartia were investigated. These extracts contained a variety of biologically active metabolites, including bombardolides, new antifungal γ-lactones; preussicyclin, a compound with a novel tetracyclic ring system; ascodesmins A–F, a series of aromatic polyketides, and several other new natural products showing antibacterial and/or antifungal effects.; Our continuing interest in the search for antfinsectan compounds led us to the investigation of Collybia dryophila, a basidiomycete. This mushroom species is anecdotally recognized as being typically free of mycetophilous insects and this became a candidate for chemical investigation. Preliminary screening of this organism indicated potent activity against the fall armyworm Spodoptera frugiperda. Subsequent chemical studies led to the isolation of three active metabolites, including a new pyridine derivative.; Extensive 1D and 2D NMR and mass spectrometric methods were used to determine the structures of these compounds. In some cases, chemical derivatization techniques were employed. Details of the isolation and structure elucidation of metabolites from these species will be presented. |
