Synthesis and biodistribution of a novel 99mTc nitrido radiopharmaceutical with proline dithiocarbamate as a potential tumor imaging agent

Radiolabeling and Biological Evaluation of Novel 99mTc-Nitrido and 99mTc-Oxo Complexes with 4-Methoxy-L-Phenylalanine Dithiocarbamate for Tumor Imaging

To develop novel radiolabeled amino acid tumor imaging agents, 4-methoxy-L-phenylalanine dithiocarbamate (MOPADTC) was synthesized successfully, and two kinds of 99mTc-labeled complexes ([99mTc]TcN-MOPADTC and [99mTc]TcO-MOPADTC) with high radiochemical purities (RCP > 95%) were obtained. The in vitro stability and partition coefficient were determined, and the results show that both of these complexes have good in vitro stability; [99mTc]TcO-MOPADTC is hydrophilic, while [99mTc]TcN-MOPADTC is slightly lipophilic. The biodistribution of [99mTc]TcN-MOPADTC and [99mTc]TcO-MOPADTC in mice bearing S180 tumors shows that the tumor uptake and tumor/muscle ratio of [99mTc]TcO-MOPADTC were higher than the tumor uptake and tumor/muscle ratio of [99mTc]TcN-MOPADTC. In addition, the tumor retention of [99mTc]TcO-MOPADTC is better than the tumor retention of [99mTc]TcN-MOPADTC. A competitive inhibition assay was performed, and the results indicate that [99mTc]TcO-MOPADTC may enter cells primarily via the L-alanine/L-serine/L-cysteine (ASC) system. Single-photon emission computed tomography (SPECT) imaging of [99mTc]TcO-MOPADTC shows obvious accumulation in tumor sites, suggesting that [99mTc]TcO-MOPADTC is a novel potential tumor-imaging agent.

Au(iii)-Proline derivatives exhibiting selective antiproliferative activity against HepG2/SB3 apoptosis-resistant cancer cells

This paper deals with the combination of a proline-based moiety with biologically active gold centers in the oxidation states +1 and +3. In particular, six Au(i)/(iii)-proline dithiocarbamato (DTC) complexes with general formulae [Au(DTC)₂] and [Au^IIIX₂(DTC)] (X = Cl, Br) are reported here. After the synthesis of the ligand and the complexes, all derivatives were characterized via several techniques and tested for their stability in DMSO/water media. This study was focused on the demonstration of a peculiar behavior of Au(iii)-DTC species in solution. Finally, the complexes were screened for their antiproliferative activity against 2 human cancer cell lines, namely HepG2 and HepG2/SB3, taken as models of hepatocellular carcinoma. The latter, chosen for its aggressiveness due to the upregulation of the anti-apoptotic protein SerpinB3, was selectively inhibited in terms of growth by some Au(iii)-DTC complexes.