Bioactive natural products from selected freshwater aquatic isolates and fungicolous Penicillium species.

摘要

Fungi have proven to be prolific sources of new bioactive compounds, and a variety of important pharmaceuticals and agrochemicals have been discovered through studies of fungal chemistry. In contrast to random screening approaches utilized in industry, our research applies ecological rationale to the selection of fungi for chemical investigation. The research described here involves chemical investigations of mycoparasitic and freshwater aquatic fungi as potential producers of novel metabolites with practical value.; Mycoparasitic fungi parasitize other fungi and often cause damage to the host species, presumably due to the production of antifungal agents by the mycoparasites. Based on this observation, we have initiated studies of fungi that attack and colonize long-lived fungal bodies (e.g., stromata) as part of our search for new antifungal natural products. Bioassay-guided fractionation of organic extracts from cultures of some selected species afforded over thirty-five secondary metabolites representing a variety of structural types. Representative compounds include indole diterpenoids, pyridine-containing terpenoid alkaloids possessing unusual polycyclic ring systems, polyketides with an azaphilone core structure, and new quinazolone alkaloids. Most of the compounds show antiinsectan and/or antifungal activity, and some of the new compounds possess novel structures.; Freshwater aquatic fungi comprise another fungal niche group that is chemically underexplored. Our previous work in this area has resulted in the isolation of a variety of new, structurally interesting natural products. During these ongoing studies, over a dozen bioactive secondary metabolites were isolated from two newly discovered aquatic fungal species. Most of these fungal metabolites represent new structures, and some possess antibacterial and/or antifungal activities.; The structures of the new secondary metabolites isolated during these studies were established by analysis of MS, NMR, chemical transformation results, and/or X-ray diffraction data. Details of the isolation, structure elucidation, and biological activity of these compounds are presented in this thesis.