Subject(s)
Antithyroid Agents/chemical synthesis , Symporters/antagonists & inhibitors , Aniline Compounds/chemical synthesis , Aniline Compounds/chemistry , Aniline Compounds/pharmacology , Animals , Antithyroid Agents/chemistry , Antithyroid Agents/pharmacology , Biological Transport/drug effects , Cells, Cultured , Drug Design , Inhibitory Concentration 50 , Rats , Structure-Activity Relationship , Symporters/metabolismABSTRACT
The standard assay for sodium iodide symporter (NIS) function is based on the measurement of radioiodide uptake ((125)I) in NIS-expressing cells. However, cost and safety issues have limited the method from being used widely. Here we describe a simple spectrophotometric assay for the determination of iodide accumulation in rat thyroid-derived cells (FRTL5) based on the catalytic effect of iodide on the reduction of yellow cerium(IV) to colorless cerium(III) in the presence of arsenious acid (Sandell-Kolthoff reaction). The assay is fast and highly reproducible with a Z' factor of 0.70. This procedure allows the screening of more than 800 samples per day and can easily be adapted to robotic systems for high-throughput screening of NIS function modulators. Using this method, the potency of several known inhibitors of NIS function was evaluated in a single day with high accuracy and reliability. Measured IC(50) values were essentially identical to those determined using Na(125)I.
Subject(s)
Biological Assay/methods , Iodides/metabolism , Symporters/metabolism , Animals , Anions/pharmacology , Biological Assay/standards , Biological Transport/drug effects , Catalysis/drug effects , Cell Line , Inhibitory Concentration 50 , Iodine Radioisotopes , Rats , Reference Standards , Reproducibility of Results , TitrimetryABSTRACT
The synthesis of ligand H3 based on a disymmetrically substituted terpyridine core functionalised by a carboxylic acid in the 6-position and a bis(carboxymethyl)aminomethyl function in the 6''-position is described. The coordination behaviour of this heptadentate (4N/3O) ligand with lanthanide cations (Ln=Eu, Gd and Tb) was studied in solution showing the formation of complexes with [Ln] stoichiometry. Complexes with general formula [Ln(H2O)2] were isolated from neutral water solutions containing equimolar amounts of cations and ligands, and the complexes were characterized in the solid state (elemental analysis, IR) and in solution (mass spectrometry). The photo-physical properties of the luminescent complexes of Eu and Tb were studied in water solution by means of absorption, steady state and time-resolved emission spectroscopies. Evolution of the luminescence lifetimes of the Eu and Tb complexes in H2O and D2O reveals the presence of two water molecules coordinated in the first coordination sphere of the cations. Despite this important hydration number, the overall luminescence quantum yields of the complexes remained elevated, especially in the case of Tb (Phi=22.0 and 6.5% respectively for Tb and Eu). Upon crystallisation the Gd complex formed dimeric species in which two gadolinium atoms are each heptacoordinated by one ligand, the coordination sphere being completed by a single water molecule and a bridging carboxylate function, pointing to different behaviours in the solid and liquid states.
