Preparation and biomolecule conjugation of [99mTc]Tc-MAG3

 [99mTc]Tc-MAG3 is one of the routine renal radiopharmaceuticals being used in nuclear medicine centers, throughout the world. This study investigated the synthesis and 99mTc-labeling of MAG3, as well as the synthesis of the S-acetyl-MAG3-NHS complexing agent, which was used for labeling bovine serum albumin (BSA) as a protein model using technetium-99m.

 S-acetyl-MAG3 was prepared by the reaction of S-acetyl thioglycolic acid and triglycine. It was also activated to its N-hydroxysuccinimide counterpart which was used for preparation of biomolecule conjugates. All compounds and intermediates were characterized by 1H NMR and LC/Mass spectroscopy.  Labeling of MAG3 with 99m-technetium was also well performed. The radiochemical purity and stability of labeled products was done by thin-layer chromatography. Also, biodistribution studies in mice was performed.

 The spectroscopic results confirmed the structure of compounds. The stability of [99mTc]Tc-MAG3  and [99mTc]Tc-MAG3-BSA was determined over 24h .It was found to drop from 90% to 60% and 99% to 80%,  respectively. There was no difference between serum and buffer results. Biodistribution studies for [99mTc]Tc-MAG3 confirmed renal excretion with injected dose per gram (%ID/g) kidney of 41.28 ± 4.70 , 45.63 ± 6.36 and 12.22 ± 2.83 after 1, 4 and 24h respectively.

 In this work, the rigorous purification processes were simplified through adjustment of molar ratios of reactants and the crude product obtained with higher yield was directly used for 99mTc labeling. The prepared labeled biomolecules conjugates showed acceptable radiochemical purity and stability. MAG3 was applicable for renal imaging according to biodistribution results.