Georgamide, a new cyclic depsipeptide with an alkynoic acid residue from an Australian cyanobacterium
1Carlson School of Chemistry, Clark University, Worcester, Massachusetts 01610, USA.
Abstract:
A cyclic depsipeptide, georgamide (1), was isolated from an Australian cyanobacterium and characterized by spectroscopic means. The constituent units were five amino acid residues, one each of L-Thr, L-Pro, L-Val, N-Me-L-Val, and N-Me-L-Phe, and two hydroxy carboxylic acids, 2(S)-hydroxy-3(R)-methylpentanoic acid and the unusual 2,2-dimethyl-3-hydroxy-7-octynoic acid. The stereochemistry was determined by hydrolysis of the peptide followed by derivatization and HPLC comparison with standard samples.
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