Lanthanide(III) complexes of some natural siderophores: A thermodynamic, kinetic and relaxometric study

Gyula Tircsó, Zoltán Garda, Ferenc K. Kálmán, Zsolt Baranyai, István Pócsi, György Balla, Imre Tóth

Research output: Contribution to journalArticle

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Abstract

Stability constants of the complexes formed between the natural trihydroxamic acids desferrioxamine B (DFB) and desferricoprogen (DFC) with NdIII, GdIII and YbIII ions were determined using pH-potentiometry. The equilibrium in these systems can be described by models containing mononuclear protonated (Ln(HL), Ln(H2L) and Ln(H3L)), deprotonated (LnL) and ternary hydroxo Ln(H- 1L) complexes, but for both ligands dinuclear complexes of low stability were also detected. The stability constants for the Ln(HDFB)+ complexes are 11.95 (NdIII), 13.16 (GdIII) and 14.67 (YbIII), while these values of the Ln(DFC) complexes are considerably higher (14.42 (NdIII), 15.14 (GdIII) and 16.49 (YbIII)). The stability constants of the complexes of DFB and DFC are much lower than those of the Ln(L)3 complexes formed with some aromatic hydroxamic acids indicating that the relatively long spacer between the hydroxamic acid moieties in DFB and DFC is unfavorable for LnIII complexation. The relaxometric study conducted for the Gd(HDFB)+ species revealed an interesting pH dependence of the relaxivity associated with a large hydration number (bishydrated complex) and fast water exchange (kex = (29.9 ± 0.4) × 106 s- 1), which would be favorable for CA use. However the dissociation of Gd(HDFB)+ is fairly fast (<2 ms) under all conditions employed in the present work thus the kinetically labile Gd(HDFB)+ is not suitable for in vivo CA applications. Some low stability ternary complexes were also detected with K(Gd(HDFB)(HCO3)) = 17.5 ± 1.9 and K(Gd(HDFB)(Lactate)) = 8.4 ± 3.2 but in the presence of citrate and phosphate ions the Gd(HDFB) + complex was found to dissociate.

Original languageEnglish
Pages (from-to)53-61
Number of pages9
JournalJournal of Inorganic Biochemistry
Volume127
DOIs
Publication statusPublished - 2013

Fingerprint

Siderophores
Lanthanoid Series Elements
Thermodynamics
Deferoxamine
Hydroxamic Acids
Kinetics
Potentiometry
Ions
Citric Acid
Lactic Acid
Complexation
Carboxylic acids
Hydration
Phosphates
Ligands
Ion exchange
Acids
desferricoprogen
Water

Keywords

  • Equilibrium
  • Kinetic inertness
  • Ln(III) complexes
  • Natural siderophores
  • Relaxivity
  • Water exchange rate

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

Cite this

Lanthanide(III) complexes of some natural siderophores : A thermodynamic, kinetic and relaxometric study. / Tircsó, Gyula; Garda, Zoltán; Kálmán, Ferenc K.; Baranyai, Zsolt; Pócsi, István; Balla, György; Tóth, Imre.

In: Journal of Inorganic Biochemistry, Vol. 127, 2013, p. 53-61.

Research output: Contribution to journalArticle

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T1 - Lanthanide(III) complexes of some natural siderophores

T2 - A thermodynamic, kinetic and relaxometric study

AU - Tircsó, Gyula

AU - Garda, Zoltán

AU - Kálmán, Ferenc K.

AU - Baranyai, Zsolt

AU - Pócsi, István

AU - Balla, György

AU - Tóth, Imre

PY - 2013

Y1 - 2013

N2 - Stability constants of the complexes formed between the natural trihydroxamic acids desferrioxamine B (DFB) and desferricoprogen (DFC) with NdIII, GdIII and YbIII ions were determined using pH-potentiometry. The equilibrium in these systems can be described by models containing mononuclear protonated (Ln(HL), Ln(H2L) and Ln(H3L)), deprotonated (LnL) and ternary hydroxo Ln(H- 1L) complexes, but for both ligands dinuclear complexes of low stability were also detected. The stability constants for the Ln(HDFB)+ complexes are 11.95 (NdIII), 13.16 (GdIII) and 14.67 (YbIII), while these values of the Ln(DFC) complexes are considerably higher (14.42 (NdIII), 15.14 (GdIII) and 16.49 (YbIII)). The stability constants of the complexes of DFB and DFC are much lower than those of the Ln(L)3 complexes formed with some aromatic hydroxamic acids indicating that the relatively long spacer between the hydroxamic acid moieties in DFB and DFC is unfavorable for LnIII complexation. The relaxometric study conducted for the Gd(HDFB)+ species revealed an interesting pH dependence of the relaxivity associated with a large hydration number (bishydrated complex) and fast water exchange (kex = (29.9 ± 0.4) × 106 s- 1), which would be favorable for CA use. However the dissociation of Gd(HDFB)+ is fairly fast (<2 ms) under all conditions employed in the present work thus the kinetically labile Gd(HDFB)+ is not suitable for in vivo CA applications. Some low stability ternary complexes were also detected with K(Gd(HDFB)(HCO3)) = 17.5 ± 1.9 and K(Gd(HDFB)(Lactate)) = 8.4 ± 3.2 but in the presence of citrate and phosphate ions the Gd(HDFB) + complex was found to dissociate.

AB - Stability constants of the complexes formed between the natural trihydroxamic acids desferrioxamine B (DFB) and desferricoprogen (DFC) with NdIII, GdIII and YbIII ions were determined using pH-potentiometry. The equilibrium in these systems can be described by models containing mononuclear protonated (Ln(HL), Ln(H2L) and Ln(H3L)), deprotonated (LnL) and ternary hydroxo Ln(H- 1L) complexes, but for both ligands dinuclear complexes of low stability were also detected. The stability constants for the Ln(HDFB)+ complexes are 11.95 (NdIII), 13.16 (GdIII) and 14.67 (YbIII), while these values of the Ln(DFC) complexes are considerably higher (14.42 (NdIII), 15.14 (GdIII) and 16.49 (YbIII)). The stability constants of the complexes of DFB and DFC are much lower than those of the Ln(L)3 complexes formed with some aromatic hydroxamic acids indicating that the relatively long spacer between the hydroxamic acid moieties in DFB and DFC is unfavorable for LnIII complexation. The relaxometric study conducted for the Gd(HDFB)+ species revealed an interesting pH dependence of the relaxivity associated with a large hydration number (bishydrated complex) and fast water exchange (kex = (29.9 ± 0.4) × 106 s- 1), which would be favorable for CA use. However the dissociation of Gd(HDFB)+ is fairly fast (<2 ms) under all conditions employed in the present work thus the kinetically labile Gd(HDFB)+ is not suitable for in vivo CA applications. Some low stability ternary complexes were also detected with K(Gd(HDFB)(HCO3)) = 17.5 ± 1.9 and K(Gd(HDFB)(Lactate)) = 8.4 ± 3.2 but in the presence of citrate and phosphate ions the Gd(HDFB) + complex was found to dissociate.

KW - Equilibrium

KW - Kinetic inertness

KW - Ln(III) complexes

KW - Natural siderophores

KW - Relaxivity

KW - Water exchange rate

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