Formation of Amides Citrate-Based Siderophores and Other Compounds

9 Formation of Amides Citrate-Based Siderophores and Other Compounds 

First works related to the citric acid amides started already in 1852 by Pebal [545] who synthesized citranilic cid (N-phenylcitric acid imide). Further investigations, in the 1872-1905 period, with various amides and rather sporadic, are these of 

These and similar syntheses made possible preparation, isolation, identification and characterization of various citrate-based siderophores [478,557-589, and many references therein]. However, this group of compounds is only to a certain extent linked with the ordinary citric acid chemistry. Siderophores are more connected with biochemical aspects of the iron-transport in living organisms Considering their biological importance, clinical applications and potential use in agriculture, a huge literature is devoted to various siderophores, but here, it is possible to pres- 

There is a large number of naturally produced terrestrial and marine siderophores but only a small group of them are derivatives of citric acid. The marine siderophores containing citrate skeleton , when coordinated with the Fe(III) chelate are photoreactive in natnral sunlight conditions of seawater [582, 586-588, 590], The photolysis of ferric chelate generates an oxidized ligand and an acceptable by cells iron in the ferrous Fe(II) form. Most of citrate-based siderophores are coming from biosynthetic procedures, but few of them were chemically synthesized and isolated in pure state [475, 564, 565, 567, 568, 573, 574, 579, 580, 591-594], 

There is no doubt that increased interest in citrate-based siderophores, with mai possibihties to synthesize them with different combinations of organic groups, will have a stimulating effect on the ordinary chemistiy of citric acid and its derivatives. Certainly, various modem experimental techniques which were applied for identification and characterization of siderophores, will also be used in the case of other organic and inorganic citrate-based compounds. 

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