Amino-acids and peptides. Part X. Characterisation of the monamycins, members of a new family of cyclodepsipeptide antibiotics
Monamycin, a crystalline antibacterial preparation isolated from cultures of Streptomyces jamaicensis, consists of a mixture of fifteen cyclohexadepsipeptides, six of which contain chlorine. Each molecular species consists of one residue of α-hydroxy-acid (either L-2-hydroxy-3-methylbutanoic acid or L-2-hydroxy-3-methylpentanoic acid) and five residues of α-amino-or imino-acid. The latter consist of N-methyl-D-leucine, L-proline (or trans-4-methyl L-proline), D-isoleucine (or D-valine), (3R)-piperazic acid [or (3R,5S)-5-chloropiperazic acid, or (3R)-4,5 (or 5,6)-dehydropiperazic acid], and (3S,5S)-5-hydroxypiperazic acid. The name piperazic acid is assigned to hexahydropyridazine-3-carboxylic acid.