Graduate Thesis Or Dissertation
 

Novel secondary metabolites from a Madagascar collection of Lyngbya majuscula

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8g84mp278

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  • Marine organisms produce a variety of secondary metabolites for defense, communication, and reproduction. While these uses are essential for the organisms' survival, marine natural products have demonstrated their value to human society as well. Asian countries used algae for centuries to treat or prevent illnesses as wide-ranging as cough, gout, gallstones, goiter, hypertension, and diarrhea. The Chinese created elixirs from the red alga Digenea simplex as a remedy for parasite infections of the intestine. The recognition of their potential as pharmaceuticals has led to extensive investigations. Recently, algae have been screened for anticancer compounds, with several cyanobacteria providing many potential candidates. A Madagascar collection of the marine cyanobacterium Lyngbya majuscula yielded two new cyclopropyl-containing fatty acid metabolites, lyngbyamides B and C. The isolation of the lyngbyamides was guided by the brine shrimp (Artemia sauna) toxicity assay. The structures were established using spectroscopic methods. Semisynthesis of the lyngbyamides was achieved by coupling the acid chloride derivative of the natural C-13 cyclopropyl fatty acid (3-(2-heptyl-cyclopropyl)-propionic acid), and the respective free amines. Bioactivity profiling was conducted for the natural and semisynthetic products using the brine shrimp toxicity assay. A novel heterocyclic sulfur-containing compound was isolated from a Madagascar collection of Lyngbya majuscula using an antifungal (Candida albicans) bioassay-guided fractionation. The structure was established using spectroscopic methods consisting primarily of 1D and 2D NMR experiments. Comparisons are made with other related natural and synthetic products.
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