99mTc-glucoheptonate-guanine: Synthesis, biodistribution and imaging in animals

Abstract

The aim of the current study was to design a nucleotide-based radiopharmaceutical which could be labeled with 99m Tc and to investigate its radiopharmaceutical efficiency and stability. GHA (glucoheptonate) was used as bifunctional chelate. GHA was labeled with 99m Tc by SnCl2 reduction method first, and then G (guanine) was conjugated with 99m Tc-GHA at 90 °C. In order to determine its radiopharmaceutical stability, thin layer radio chromatography (TLRC) and electrophoresis were employed. In addition, the results were confirmed using high performance liquid radio chromatography (HPLRC). Scintigraphic imaging was performed on rats with mammary tumors, while tissue distribution was determined on Albino Wistar rats. Labeling yield was found to be over 95% and the labeled complex maintained its stability during the study period. The lipophilicity of the 99m Tc-GHG was measured and the partition coefficient (logP) of the labeled compound calculated. The results demonstrated that the uptake of 99m Tc-GHG ( 99m Tc-glucoheptonate-guanine) reached its maximum at 3 hours p.i. in stomach and intestines. Main way of excretion was renal. Hepatobiliary excretion was also observed. In conclusion, 99m Tc-GHG may be useful as a nucleotide-based radiopharmaceutical for in vivo applications.