ic301081a_si_001.pdf (220.66 kB)

Oxinobactin and Sulfoxinobactin, Abiotic Siderophore Analogues to Enterobactin Involving 8‑Hydroxyquinoline Subunits: Thermodynamic and Structural Studies

Download (220.66 kB)
journal contribution
posted on 19.11.2012 by Amaury du Moulinet d’Hardemare, Gisèle Gellon, Christian Philouze, Guy Serratrice
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 potentiometric and spectrophotometric titrations in methanol–water 80/20% w/w solvent for oxinobactin and in water for sulfoxinobactin. They reveal the extraordinarily complexing 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).

History

Exports