First synthesis of the chiral mixed O/S ligands, 1,2-sulfinyl thiols: application as chiral proton sources in enantioselective protonations of enolates

Synthesis of radioiodine labeled dibenzyl disulfide for evaluation of tumor cell uptake

Benzyl 4-halobenzyl and ally benzyl disulfide were synthesized as diallyl disulfide analogues and their tumor growth inhibitory effects on the cancer cells (SNU C5 and MCF-7) were comparable to that of diallyl disulfide, indicating that the disulfide functional group was responsible for the tumor growth inhibitory effects. Cu(I)-assisted radioiodination of benzyl 4-bromobenzyl disulfide gave benzyl 4-[123I/125I]iodobenzyl disulfide in 30-40% radiochemical yield. The radiolabeled disulfide was taken up by the cancer cells in a time-dependent manner, and the uptake was inhibited by the pretreatment of S-methyl methanethiosulfonate (MMTS), phorone and diallyl disulfide. This study suggested that the radiolabeled dibenzyl disulfide was taken up by the cancer cells via thiol-disulfide exchange and retained inside the cells.

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.