title: Biospeciation of various antidiabetic V(IV)O compounds in serum.
abstract: The interactions of various insulin mimetic oxovanadium(IV) compounds with serum proteins were studied in model systems and in ex vivo samples. For the modeling study, an earlier in situ method was extended and applied to the formation of ternary complexes of apotransferrin (apoTf)-V(IV)O-maltol (mal) and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone (dhp). Both systems were evaluated via simultaneous CD and EPR measurements. Determination of the formation constants of the ternary complexes allowed the calculation of more accurate stability constants for the V(IV)O-apoTf parent complexes and establishment of a better model for drug speciation in serum. It was found that dhp and the synergistic carbonate are non-competitive binders. Based on the stability constants obtained for V(IV)O-apoTf complexes and estimated for V(IV)O-HSA (= human serum albumin), modeling calculations were performed on the distribution of V(IV)O among the components of blood serum. The results were confirmed by HPLC-ICP-MS (liquid chromatography-inductively coupled plasma spectroscopy-mass spectrometry) measurements. The ex vivo interactions of the V(IV)O complexes formed with mal, picolinic acid (pic) and dhp with serum protein standards and also with human serum samples were evaluated. The proteins were firstly separated by (HPLC), and the V content of each fraction was determined by ICP-MS. All the studied V(IV)O compounds displayed similar chromatographic profiles, associated almost exclusively with apotransferrin as predicted by the modeling calculations. Under physiological conditions, the interactions with HSA of all of the species under study were negligible. Therefore Tf seems to be the main V(IV)O transporter in the serum under in vitro conditions, and this association is practically independent of the chemical form in which V(IV)O is administered.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged, H-6701, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Jakusch
authors.forename: Dominik
authors.initials: D
authors.lastname: Hollender
authors.forename: Eva Anna
authors.initials: EA
authors.lastname: Enyedy
authors.forename: Cristina Sánchez
authors.initials: CS
authors.lastname: González
authors.forename: Maria
authors.initials: M
authors.lastname: Montes-Bayón
authors.forename: Alfredo
authors.initials: A
authors.lastname: Sanz-Medel
authors.forename: João
authors.initials: J
authors.lastname: Costa Pessoa
authors.forename: Isabel
authors.initials: I
authors.lastname: Tomaz
authors.forename: Tamás
authors.initials: T
authors.lastname: Kiss
mesh_terms: D001059:Apoproteins / Q000097:blood* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D000077543:Deferiprone; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood* / Q000737:chemistry; D013058:Mass Spectrometry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000097:blood* / Q000737:chemistry; D011728:Pyridones / Q000737:chemistry; D011753:Pyrones / Q000097:blood* / Q000737:chemistry; D012709:Serum Albumin / Q000737:chemistry; D013816:Thermodynamics; D013997:Time Factors; D014168:Transferrin / Q000737:chemistry; D014462:Ultrafiltration; D014639:Vanadium / Q000097:blood* / Q000737:chemistry
chemical_list: D001059:Apoproteins; D007004:Hypoglycemic Agents; D009942:Organometallic Compounds; D011728:Pyridones; D011753:Pyrones; D012709:Serum Albumin; D014168:Transferrin; C028284:apotransferrin; D014639:Vanadium; D000077543:Deferiprone; C008316:maltol