title: Synthesis of radioiodine-labeled 2-phenylethyl 1-thio-beta-D-galactopyranoside for imaging of LacZ gene expression.
abstract: A potent inhibitor of beta-galactosidase (EC 3.2.1.23), 2-phenylethyl 1-thio-beta-D-galactopyranoside (PETG), was radioiodinated for noninvasive imaging of LacZ gene expression. In order to introduce radioiodine to the phenyl ring of PETG, 2-(4-bromophenyl)ethanethiol was prepared and attached to the C-1 position of beta-D-galactose pentaacetate under conditions that resulted in the exclusive formation of the beta anomer. The bromo group of PETG was converted to the tributylstannyl group where radioiododemetallation was carried out. Radioiodine-labeled PETG tetraacetate was purified by HPLC, which can be used as a prodrug for biological evaluation or hydrolyzed to 2-(4-[123I/125I]iodophenyl)ethyl 1-thio-beta-D-galactopyranoside ([123I/125I]7) under basic conditions. The resulting radioiodine-labeled PETG was obtained in overall 62% radiochemical yield (decay-corrected) and with specific activity of 46-74 GBq/micromol.
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Republic of Korea.
authors.forename: Joon Hun
authors.initials: JH
authors.lastname: Choi
authors.forename: Yearn Seong
authors.initials: YS
authors.lastname: Choe
authors.forename: Kyung-Han
authors.initials: KH
authors.lastname: Lee
authors.forename: Yong
authors.initials: Y
authors.lastname: Choi
authors.forename: Sang Eun
authors.initials: SE
authors.lastname: Kim
authors.forename: Byung-Tae
authors.initials: BT
authors.lastname: Kim
mesh_terms: D003952:Diagnostic Imaging / Q000379:methods*; D004791:Enzyme Inhibitors / Q000138:chemical synthesis; D015870:Gene Expression; D017930:Genes, Reporter; D007457:Iodine Radioisotopes; D007763:Lac Operon / Q000235:genetics*; D013862:Thiogalactosides / Q000138:chemical synthesis*; D001616:beta-Galactosidase / Q000037:antagonists & inhibitors
chemical_list: D004791:Enzyme Inhibitors; D007457:Iodine Radioisotopes; D013862:Thiogalactosides; C066907:phenylethylthio-beta-galactopyranoside; D001616:beta-Galactosidase