Investigation of physicochemical and in-vivo behavior of diastereomeric iron-59, gallium-68, and indium-111-EHPG trivalent metal complexes.

Abstract

EHPG (N, N'-ethylenebis-[2-(o-hydroxyphenyl)glycine]) trivalent metal complexes show diagnostic potential both in radiopharmaceutical applications (gallium-68, indium-111) and as MRI contrast agents (iron). Although several publications report similar behavior of iron, gallium and indium complexes, we observe significant differences between EHPG complexes of these metals both in physicochemical and in vivo analyses. In addition, stereospecific behavior has been observed for the two diastereomers of EHPG when complexed with each metal. Complexes of Fe[59Fe], 68Ga, and 111In with meso, racemic, and unseparated EHPG have been evaluated. Relative lipophilicity has been measured with HPLC. Blood clearance and liver uptake have been correlated with pM values, stability constants and metal ion reduction potentials.