title: Testimony of the correlation between DHEA and bioavailable testosterone using a biochromatographic concept: effect of two salts.
abstract: In a previous paper (C. André et al., submitted to J. Chromatogr. B) a mathematical model based on the Langmuir theory was developed to visualize the competition effect between testosterone and deshydroepiandrosterone (DHEA) for their identical human serum albumin (HSA) binding cavity. In this work, the thermodynamic mechanisms of (i) the binding of two hormones, DHEA and testosterone to HSA and (ii) the testosterone displacement of its HSA binding cavity by DHEA was studied by biochromatography. The Na+ cation effect used as physico-chemical marker of these binding processes was clearly described. The Gibbs free energy value (DeltaGo ) of the displacement equilibrium was always negative demonstrating that DHEA well displaced testosterone of its HSA binding cavity. The thermodynamic data also showed that this displacement equilibrium was enthalpically controlled. Moreover, the effect of (Mg2+) concentration (x') on the two binding mechanisms was analyzed. It appeared that for old men with a deficit of testosterone, Mg(2+) supplementation during treatment with DHEA can increased the free testosterone concentration and its biological effect. All these results must be confirmed by in vivo test.
authors.affiliation: Equipe des Sciences Séparatives et Biopharmaceutiques (2SB), Laboratoire de Chimie Analytique, Faculté de Médecine et de Pharmacie, Place Saint-Jacques, 25030 Besançon cedex, France.
authors.forename: Claire
authors.initials: C
authors.lastname: André
authors.forename: Alain
authors.initials: A
authors.lastname: Berthelot
authors.forename: Jean François
authors.initials: JF
authors.lastname: Robert
authors.forename: Mireille
authors.initials: M
authors.lastname: Thomassin
authors.forename: Yves Claude
authors.initials: YC
authors.lastname: Guillaume
mesh_terms: D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003687:Dehydroepiandrosterone / Q000737:chemistry / Q000493:pharmacokinetics*; D006801:Humans; D008274:Magnesium / Q000737:chemistry; D011485:Protein Binding / Q000502:physiology; D012492:Salts / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry / Q000493:pharmacokinetics*; D012964:Sodium / Q000737:chemistry; D013739:Testosterone / Q000737:chemistry / Q000493:pharmacokinetics*; D013816:Thermodynamics
chemical_list: D012492:Salts; D012709:Serum Albumin; D013739:Testosterone; D003687:Dehydroepiandrosterone; D012964:Sodium; D008274:Magnesium