Synthesis and biodistribution of a new (99m) Tc-oxo complex with deoxyglucose dithiocarbamate for tumor imaging

The deoxyglucose dithiocarbamate (DGDTC) was radiolabeled with (99m) Tc(V)-glucoheptonate (GH), for the potential use as radiopharmaceuticals for tumor imaging. For labeling, (99m) TcO-DGDTC was prepared by ligand-exchange reaction with (99m) Tc-GH. The radiochemical purity of the (99m) TcO-DGDTC complex was over 90% by thin-layer chromatography and high-performance liquid chromatography, without any notable decomposition at room temperature over a period of 6 h. Its partition coefficient indicated that it was a hydrophilic complex. The ligand-exchange reaction occured at neutral condition and under 100 °C for 15 min to achieve high radiochemical purity. In vitro cell studies showed there was an increase in the uptake of (99m) TcO-DGDTC as a function of incubation time and the cellular uptake of (99m) TcO-DGDTC was possibly mediated by way of a d-glucose mechanism. The biodistribution of (99m) TcO-DGDTC in mice bearing S 180 tumor showed that the complex accumulated in the tumor with good uptake and excellent retention. As compared with other reported (99m) Tc radiolabeled glucose derivatives, (99m) TcO-DGDTC showed the highest tumor uptake and good tumor/muscle ratios. The tumor/muscle ratio of (99m) TcO-DGDTC uptake was higher than that of [(18) F] FDG uptake. Single photon emission computed tomography (SPECT) image studies showed there was a visible accumulation in tumor sites, suggesting (99m) TcO-DGDTC would be a promising candidate for tumor imaging.