Synthesis of a radioiodinated thymidine phosphorylase inhibitor and its preliminary evaluation as a potential SPECT tracer for angiogenic enzyme expression

摘要

The expression of thymidine phosphorylase (TP) is strongly associated with angiogenesis in tumors and activation of antitumor agents. We designed a novel 5-~(125)I-labeled 6-(2-iminoimidazolidinyl)methyluracil hydrochloride ([~(125)I]5I6IMU-HCI) to develop an effective radiotracer for in vivo assessment of TP expression in tumors and prognosis of cancer chemotherapy. Radiotracer synthesis was achieved by radioiodination of the precursor, 6-(2-iminoimidazolidinyl)methylur-acil at the C-5 position with NCS/radioiodide. After purification by HPLC, [~(125)I]5I6IMU-HCI was obtained in high radiochemical yield with satisfactory specific activity. The radiotracer showed high inhibitory potency for the target enzyme and good stability in vivo.