Crepenynate-derived specialized natural products

Michael Ronald Shepard Jr., Purdue University


Lipophilic specialized natural products in eukaryotes, as represented by the linear polyacetylenes, can be produced through the modification of primary metabolic fatty acids by the addition of various functional groups, fatty acid elongation, or by chain shortening, each of which adds to the array of biologically active metabolites. Increasing our fundamental understanding of the lipid metabolic pathways and the specialized enzymes required for the formation of these natural products may allow for the future development of transgenic organisms with commercially sufficient yields of high-value products, either pharmaceuticals or basic chemical building blocks. In the current work, three studies of crepenynate-derived lipophilic natural products from representative plant and fungal species were undertaken. To gain insight into the mechanism of the diverged desaturase reactions, kinetic isotope effect studies upon of FAD2-related enzymes that convert the natural product crepenynic acid to dehydrocrepenynic acid, a compound with cis-enyne functionality, were undertaken. Second, an extensive study of the specialized metabolic processes leading to the alkamides of Echinacea purpurea laid a foundation for a model integrating lipid and amino acid metabolism in this widely used natural remedy. Finally, a study was carried out on the difficulties of synthesizing enantiospecifically hydroxylated lipophilic natural products (i.e., falcarindiol). Collectively, the studies described in this thesis further the knowledge of metabolic pathways for the formation of specialized acetylenic natural products.




Minto, Purdue University.

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