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The synthesis of two new iron chelators built on the tris-L-serine trilactone scaffold of enterobactin and bearing a 8-hydroxyquinoline (oxinobactin) or 8-hydroxyquinoline-5-sulfonate (sulfoxinobactin) unit has been described. The X-ray structure of the ferric oxinobactin has been determined, exhibiting a slightly distorted octahedral environment for Fe(Ⅲ) and a Δ configuration. The Fe(Ⅲ) chelating properties have been examined by Potentiometrie and spectrophotometric titrations in methanol--water 80/20% w/w solvent for oxinobactin and in water for sulfoxinobactin. They reveal the extraordinarily completing ability (pFeⅢ values) of oxinobactin over the p[H] range 2--9, the pFe value at p[H] 7.4 being 32.8. This was supported by spectrophotometric competition showing that oxinobactin removes Fe (Ⅲ) from ferric enterobactin at p[H] 7.4. In contrast, the Fe (III) affinity of sulfoxinobactin was largely lower as compared to oxinobactin but similar to that of the ligand O-TRENSOX having a TREN backbone. These results are discussed in relation to the predisposition by the trilactone scaffold of the chelating units. Some comparisons are also made with other quinoline-based ligands and hydroxypyridinonate ligand (hopobactin). [ABSTRACT FROM AUTHOR]

Abstract: The story of the highly selective iron(III) chelating agent O-TRENSOX is presented. The promising (and somewhat unexpected in regard to partition coefficients) properties of this molecule induced the development of several tools for iron metabolism studies. The tuning of the properties of O-TRENSOX by chemical modifications of the parent molecules is also developed. Finally, fascinating perspectives are opened by amphiphilic derivatives which mimic marine siderophores from phytoplankton. The self-assembling properties of amphiphilic abiotic chelators and their iron derivatives, as well as the first results concerning iron nutrition of Erwinia chrysanthemi and some mutants, have been studied. [Copyright &y& Elsevier]

Abstract: Oxinobactin, a siderophore analogue to enterobactin but possessing 8-hydroxyquinoline instead of catechol complexing subunits, has been synthesized starting from l-serine and 8-hydroxyquinoline. Comparative iron binding studies showed that oxinobactin is as effective as enterobactin for the complexation of FeIII at physiological pH but with improved complexing ability at acidic pH. [Copyright &y& Elsevier]