Nalpha-acetylfusarinines: isolation, characterization, and properties.

The isolation, purification, and structural elucidation of a new group of naturally occurring hydroxamic acids are described. These compounds are produced by an unidentified species of Penicillium when grown on iron deficient medium. They are closely related structurally to the fusarinines, whose basic structure contains Ndelta-(cis-5-hydroxy-3-methylpent-2-enoyl)-Ndelta-hydroxy-L-ornithine, but the alpha-amino groups in the new compounds are protected by Nalpha acetyl groups. The most complex of the compounds is N,N',N"-triacetylfusarinine C, or N,N'N"-triacetylfusigen, a cyclic triester composed of three molecules on Nalpha-acetylfusarinine. The trimer has growth factor activity for Arthrobacter JG-9 about equal to fusarinine C itself. The monohydroxamate, Nalpha-acetylfusarinine, is more active than the trimer. The greater chemical stability of these compounds compared to the unacetylated fusarinines reconciles the utilization of otherwise unstable amino acid esters as iron transport agents.