Search

In this report, we describe the radiosynthesis of a new thiol-targeting prosthetic group for efficient radioactive iodine labeling of biomolecules. Radioiodination using the precursor 3 was performed to obtain 125 I-labeled tetrazole 4b with high radiochemical yield (73%) and radiochemical purity. Using the radiolabeled 4b , a single free cysteine containing peptide and human serum albumin were labeled with 125 I in modest-to-good radiochemical yields (65–99%) under mildly reactive conditions. A biodistribution study of [ 125 I] 7 in normal ICR mice exhibited lower thyroid uptake values than those of 125 I-labeled human serum albumin prepared via a traditional radiolabeling method. Thus, [ 125 I] 7 could be employed as an effective radiotracer for molecular imaging and biodistribution studies. The results clearly demonstrate that 4b has the potential to be effectively implemented as a prosthetic group in the preparation of radiolabeled biomolecules. [ABSTRACT FROM AUTHOR]

In this report, we present a rapid and highly efficient method for radioactive iodine labeling of trans -cyclooctene group conjugated biomolecules using inverse-electron-demand Diels–Alder reaction. Radioiodination reaction of the tetrazine structure was carried out using the stannylated precursor 2 to give 125 I-labeled product ([ 125 I] 1 ) with high radiochemical yield (65 ± 8%) and radiochemical purity (>99%). For radiolabeling application of [ 125 I] 1 , trans -cyclooctene derived cRGD peptide and human serum albumin were prepared. These substrates were reacted with [ 125 I] 1 under mild condition to provide the radiolabeled products [ 125 I] 6 and [ 125 I] 8 , respectively, with excellent radiochemical yields. The biodistribution study of [ 125 I] 8 in normal ICR mice showed significantly lower thyroid uptake values than that of 125 I-labeled human serum albumin prepared by a traditional radiolabeling method. Therefore [ 125 I] 8 will be a useful radiolabeled tracer in various molecular imaging and biological studies. Those results clearly demonstrate that [ 125 I] 1 will be used as a valuable prosthetic group for radiolabeling of biomolecules. [ABSTRACT FROM AUTHOR]