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  • 1 Changsha University of Science and Technology College of Chemistry and Environmental Engineering 45 Chiling Road Changsha Hunan 410076 P.R. China
  • 2 Chinese Academy of Sciences Radiopharmaceutical Centre, Shanghai Institute of Applied Physics 2019 Jialuo Road Jiading, Shanghai 201800 P.R. China
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Radiolabeling of biologically active molecules with fac-[188Re(CO)3(H2O)3]+ unit has been of primary interest in recent years. Therefore, we herein report ligands L1−L4 (L1=histidine, L2=nitrilotriacetic acid, L3=2-picolylamine-N,N-diacetic acid, L4=bis(2-pyridymethy)amine) that have been evaluated by radiochemical reactions with fac-[188Re(CO)3(H2O)3]+. These reactions yielded the radioactive complexes of fac-[188Re(CO)3L] (L = L1−L4, 188Re tricarbonyl complexes 1–4), which were identified by HPLC. Complexes 1–4, with log Po/w values ranging from −2.23 to 2.18, were obtained with yields of ≥95% using ligand concentrations within 10−6–10−4M range. Thus, specific activities of 220 GBq/μmol could be achieved. Challenge studies with cysteine and histidine revealed high stability for all of these radioactive complexes, and biodistribution studies in mice indicated a fast rate of blood clearance and high rate of total radioactivity excretion occurring primarily through the renal-urinary pathway. In summary, the ligands L1–L4 are potent chelators for the future functionalization of biomolecules labeling with fac-[188Re(CO)3(H2O)3]+.