| Abstract
| - The lipid extract of a Madagascan Lyngbya majuscula has yielded malyngamides Q and R, both amidesof 7-methoxytetradec-4-enoic acid. The isolation of these metabolites was accomplished using preparativeliquid chromatography, with final purification through repetitive reversed-phase HPLC. Structureelucidation was accomplished utilizing 1D and 2D NMR spectroscopic characterization of the naturalproducts and comparisons with malyngamides A and B. DPFGSE 1D NOE data suggested a differentgeometrical stereochemistry at C-6 in malyngamides Q and R from that observed for malyngamide A, aswell as the other known malyngamides. The Z stereochemistry was confirmed for malyngamide R bymeasurement of key diagnostic 3JCH couplings utilizing the HSQMBC pulse sequence. The absolutestereochemistry of C-4‘ ‘ of the pyrrolidone ring was defined by chiral GCMS analysis of serine releasedby ozonolysis and acid hydrolysis.
|
