Evaluation of New Tc(CO) + Radiolabeled Glycylglycine .

Background: Peptide-based agents are used in molecular imaging due to their unique properties, such as rapid clearance from the circulation, high affinity and target selectivity. Many of the radiolabeled peptides have been clinically experienced with diagnostic accuracy. The aim of this study was to investigate biological behavior of [Tc(CO)(HO)]+ radiolabeled glycylglycine (GlyGly).

Methods: Glycylglycine was radiolabeled with a high radiolabeling yield of 94.69±2%, and quality control of the radiolabeling process was performed by thin layer radiochromatography (TLRC) and High-Performance Liquid Radiochromatography (HPLRC). Lipophilicity study for radiolabeled complex (Tc(CO)-Gly-Gly) was carried out using solvent extraction. The evaluation was performed by both biodistribution and SPECT imaging.

Results: The high radiolabelling yield of Tc(CO)-GlyGly was obtained and verified by TLRC and HPLRC as well. According to the results, SPECT images and biodistribution data are in good accordance. The excretion route from the body was both hepatobiliary and renal.

Conclusion: This study shows that Tc(CO)-GlyGly has the potential to be used as a peptide-based imaging agent. Further studies, Tc(CO)-GlyGly can be performed on tumor-bearing animals.