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Dhingra, K ; Fousková, P ; Angelovski, G ; Maier, ME ; Logothetis, NK ; Tóth, E

Towards extracellular Ca2+ sensing by MRI : synthesis and calcium-dependent 1H and 17O relaxation studies of two novel bismacrocyclic Gd3+ complexes

Journal of Biological Inorganic Chemistry 13 (1) 35-46

par Administrateur - publié le

Abstract :

Two new bismacrocyclic Gd3+ chelates containing a specific Ca2+ binding site were synthesized as potential MRI contrast agents for the detection of Ca2+ concentration changes at the millimolar level in the extracellular space. In the ligands, the Ca(2+)sensitive BAPTA-bisamide central part is separated from the DO3A macrocycles either by an ethylene (L-1) or by a propylene (L-2) unit [H(4)BAPTA is 1,2-bis(o-aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid ; H(3)DO(3)A is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid]. The sensitivity of the Gd3+ complexes towards Ca2+ and Mg2+ was studied by H-1 relaxometric titrations. A maximum relaxivity increase of 15 and 10% was observed upon Ca2+ binding to Gd2L1 and Gd(2)L2, respectively, with a distinct selectivity of Gd2L1 towards Ca2+ compared with Mg2+.