Biodistribution of Novel 188Re-Tricarbonyl Complexes in Mice
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Graphical Abstract
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Abstract
Three novel tridentate ligands (L1NH2 = bis(2-pyridylmethyl)-amino)-ethylamine, L2H = bis(2-pyridylmethyl)-amino)-acetic acid, L3NH2 = (6-amino-hexyl)-pyridyl-2-methyl-amino-acetic acid) were used as bifunctional chelating agents for the organometallic precursor fac-188Re (CO)3(H2O)3+. The results of labeling condition experiments show that a radiochemical purity higher than 92% can be obtained within 60 min by the reaction of fac-188Re (CO)3+ core in a condition (pH=7.4) with a very small amount (10-5mol/L) of these three ligands. The stability experiments in vitro demonstrate that fac-188Re(CO)3L1NH2+, fac-188Re(CO)3L2H and fac-188Re(CO)3L3NH2 do not decompose within 24 h (37 ℃, new born calf serum). Biodistributions results indicate that the complexes with tridentate coordinated ligand systems revealed generally a good and fast clearance from all organs and tissues, primarily through the renalurinary pathway with a small portion retained in the hepatobiliary tract. The predominant route of excretion, the urinary tract, seems to correlate with the lg P values found for the complexes. The highest hepatic retention was found for the complex 188Re(CO)3L3NH2 with a lg P value of -0.36. On the basis of these experiments, it appears that functionalization of biomolecules with tridentatechelating ligand systems is feasible for the labeling with fac-188Re(H2O)3(CO)3+ .
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