Radioiodination of 1-(2-deoxy- β- d-ribofuranosyl)-2,4-difluoro-5-iodobenzene (dRFIB), a putative thymidine mimic nucleoside for cell proliferation studies

• Published in: Applied radiation and isotopes 2008-09, Vol.66 (9), p.1221-1228
• Main Authors: Stahlschmidt, Anke, Machulla, Hans-Jürgen, Reischl, Gerald, Knaus, Edward E., Wiebe, Leonard I.
• Format: Article
• Language: English
• Subjects: 1-(2-deoxy- β- d-ribofuranosyl)-2; 4-difluoro-5-iodobenzene; Cell Proliferation; Deoxyribonucleosides - chemical synthesis; Deoxyribonucleosides - chemistry; Difluorophenyl deoxyribonucleosides; dRFIB; I-124; Iodine Radioisotopes; Isotope Labeling - methods; Molecular Mimicry; Radioiodination; Thymidine - analogs & derivatives; Thymidine mimic
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2008.01.014

Iodine-124 was produced via the 124Te(p,n) 124I reaction by 15 MeV proton irradiation of an in-house solid mass tellurium dioxide target, using the Tübingen PETtrace TM (General Electric Medical Systems) cyclotron. 1-(2-Deoxy- β- d-ribofuranosyl)-2,4-difluoro-5-iodobenzene (dRFIB), a stable, non-polar thymidine mimic nucleoside, was synthesized in 5 steps following a literature method, for radioiodination with [ 124I] iodide via isotope exchange in the presence of copper sulphate and ammonium sulphate in methanol-water. The radiolabelling procedure was optimized with respect to temperature, amount of dRFIB, amount of sodium hydroxide and reaction time, to produce radiochemical yields of up to 85% with a 1-h reaction at 140 °C. With routine I-124 production of 30 MBq/run, relatively high specific activities, approaching 100 MBq/mmol, can be expected. The activation energy for dRFIB radioiodination was calculated from temperature-time RCY data to be approximately 100 kJ/mol using no-carrier-added [ 124I]iodide.