Vanadate complexes in serum: a speciation modeling study.
Tamás Jakusch1, Annalisa Dean, Tamás Oncsik
1Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary.
Dalton Transactions (Cambridge, England : 2003)
|December 22, 2009
Summary
Vanadate (V(V)) forms stable complexes with drug candidates like 2-hydroxypyridine-N-oxide (Hhpno). Apotransferrin (apoTf) is identified as the primary V(V) binder in serum, with human serum albumin (HSA) playing a minor role.
Area of Science:
- Inorganic Chemistry
- Medicinal Chemistry
- Biochemistry
Background:
- Vanadate (V(V)) compounds are investigated for therapeutic potential.
- Understanding V(V) speciation and binding in biological systems is crucial for drug development.
Purpose of the Study:
- To determine the speciation of vanadate with drug candidate ligands 2-hydroxypyridine-N-oxide (Hhpno) and 2-mercaptopyridine-N-oxide (Hmpno).
- To compare the stability of V(V) complexes with various ligands.
- To investigate the binding of V(V) to apotransferrin (apoTf) and human serum albumin (HSA) under physiological conditions.
Main Methods:
- pH-metric and (51)V-NMR spectroscopy were used to determine V(V) speciation.
- X-ray diffraction was employed to determine the crystal structure of a V(V) complex.
- (51)V-NMR spectroscopy and ultrafiltration were used for stability studies with apoTf.
- Fluorimetry was used to assess V(V) interaction with HSA.
Main Results:
- The predominant V(V) species with Hhpno and Hmpno at pH 7.4 were VO(2)L(2) and VO(2)L(OH).
- The stability sequence of V(V) complexes was determined as hpno > maltol ≈ hdp >> mpno > picolinic acid.
- High stability constants for V(V)-apoTf binding were determined, indicating no competition with bicarbonate.
- No significant interaction was detected between V(V) and HSA.
Conclusions:
- Apotransferrin (apoTf) is likely the primary V(V) binder in serum.
- Even with stable V(V) ligands like Hhpno and maltol, apoTf remains the dominant binder.
- Human serum albumin (HSA) plays a negligible role in V(V) binding under physiological conditions.
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