Structure of triornicin, a new siderophore.

Spectroscopic analysis of the tumor inhibitory factor triornicin produced by epicoccum purpurascens indicated that it was of similar structure to the known siderophore desferricoprogen, which is also produced by the fungus. The 1H and 13C NMR spectra indicated the replacement of an (E)-5-hydroxy-3-methyl-2-pentenoyl moiety of the desferricoprogen structure with an acetyl function. Cleavage of triornicin with basic methanol produced two fragments. The first was identified as a natural siderophore, dimerumic acid, which was also produced by basic cleavage of desferricoprogen. The second compound was identified as N alpha, N delta-diacetyl-N delta-hydroxyornithine. The structure of these fragments serves to define the structure of triornicin as a new siderophore.