Structure of Majusculamide C, a Cyclic Depsipeptide from Lyngbya majuscula

Article abstract of DOI:10.1021/jo00176a004

Majusculamide C, a novel cyclic depsipeptide that inhibits the growth of a number of fungal plant pathogens, has been shown to consist of seven α-amino acid units, one β-amino acid unit, and one hydroxy acid unit.The structures of the units have been determined by acid hydrolysis of the fungicide to glycine, L-alanine, L-N-methylpivaline, L-N,O-dimethyltyrosine, racemic 2-amino-4-methylpentanone, 3-amino-2-methylpentanoic acid of undefined stereochemistry, and N-<2(S)-hydroxy-3(S)-methylpentanoyl>glycine.Sequencing of the units implied from the structures of the hydrolysis products has been achieved by mass spectral and proton NOE studies.