Synthesis of radioiodine-labeled 2-phenylethyl 1-thio-beta-D-galactopyranoside for imaging of LacZ gene expression.
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.
Choi
Joon Hun
JH
Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Republic of Korea.
Choe
Yearn Seong
YS
Lee
Kyung-Han
KH
Choi
Yong
Y
Kim
Sang Eun
SE
Kim
Byung-Tae
BT
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
D004791:Enzyme Inhibitors; D007457:Iodine Radioisotopes; D013862:Thiogalactosides; C066907:phenylethylthio-beta-galactopyranoside; D001616:beta-Galactosidase