[en] A constrained derivative of Gd-PCTA12, Gd-cyclo-PCTA12, in which one ethylene bridge connecting two nitrogen atoms of the triamine block is replaced by a cyclohexylene bridge, was synthesized and the impact of rigidification was studied by comparing the physicochemical and relaxometric properties of both gadolinium MRI contrast agents, Gd-PCTA12 and Gd-cyclo-PCTA12. The new complex has higher proton relaxivity than the parent compound (r(1) =6.1 s(-1) mM(-1) at 20 MHz and 310 K). The rigidification of the PCTA12 scaffold proved to have no impact on the inertness towards transmetallation by endogenous ions such as Zn2+. Moreover, for both contrast agents, the relaxivity was not quenched by endogenous anions. The oxygen-17 NMR study and the NMRD profile demonstrated that the rigidification of the PCTA scaffold had no impact on the electronic relaxation of Gd-cyclo-PCTA 12. However, the rigidity of this complex induced an acceleration of the exchange rate of the inner-sphere water molecules as a result of steric crowding around the gadolinium ion. The value of tau(310)(M) thus approached the optimal value required to attain high relaxivity once the chelate is immobilized by covalent or non-covalent binding to macromolecules
Disciplines :
Radiology, nuclear medicine & imaging Chemistry
Author, co-author :
Port, M.
Raynal, I.
Vander Elst, Luce ; Université de Mons > Faculté de Médecine et de Pharmacie > Biochimie métabolique et moléculaire
Muller, Robert ; Université de Mons > Faculté de Médecine et de Pharmacie > Chimie générale, organique et biomédicale
Dioury, F.
Ferroud, C.
Guy, A.
Language :
English
Title :
Impact of rigidification on relaxometric properties of a tricyclic tetraazatriacetic gadolinium chelate
Publication date :
01 January 2006
Journal title :
Contrast Media and Molecular Imaging
ISSN :
1555-4309
Publisher :
John Wiley & Sons, Hoboken, United States - New Jersey