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N-acetylglucosaminyltransferase V (GnT-V) is one of the most relevant glycosyltransferases to tumor invasion and metastasis. Based on previous findings of molecular recognition between GnT-V and synthetic substrates, we designed and synthesized a p-iodophenyl-derivatized trisaccharide, 2-(4-iodophenyl)ethyl 6-O-[2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-d-mannopyranosyl]-β-D-glucopyranoside (IPGMG, 1) and its radiolabeled form, [(125)I]IPGMG ([(125)I]1), for use in assays of GnT-V activity in vitro. The tributyltin derivative, 2-[4-(n-tributylstannyl)phenyl]ethyl 6-O-[2-O-(3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-β-D-glucopyranosyl)-3,4,6-tri-O-acetyl-α-D-mannopyranosyl]-2,3,4-tri-O-acetyl-β-D-glucopyranoside (21), was synthesized as a precursor for the preparation of [(125)I]1. The iododestannylation of 21 using hydrogen peroxide as an oxidant followed by deacetylation yielded [(125)I]1. When [(125)I]1 was incubated in GnT-V-expressing cells with a UDP-GlcNAc donor, the production of β1-6GlcNAc-bearing IPGMG (IPGGMG, 2) was confirmed by radio-HPLC. In kinetic analysis, 1 was found to be a good substrate with a K(m) of 23.7 μM and a V(max) of 159 pmol/h. μg protein. [(125)I]1 would therefore be a useful synthetic substrate for the quantitative determination of GnT-V activity., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

C-11- and I-123-labeled long chain fatty acid derivatives have been reported as useful radiopharmaceuticals for the estimation of myocardial fatty acid metabolism. We have reported that Tc-99m-labeled N-[[[(2-mercaptoethyl)amino]carbonyl]methyl]-N-(2-mercaptoethyl)-6-aminohexanoic acid ([(99m)Tc]MAMA-HA), a medium chain fatty acid derivative, is metabolized by beta-oxidation in the liver and that the MAMA ligand is useful for attaching to the omega-position of fatty acid derivatives as a chelating group for Tc-99m. On the basis of these findings, we focused on developing a Tc-99m-labeled long chain fatty acid derivative that reflected fatty acid metabolism in the myocardium. In this study, we synthesized a dodecanoic acid derivative, MAMA-DA, and a hexadecanoic acid derivative, MAMA-HDA, and performed radiolabeling and biodistribution studies. [(99m)Tc]MAMA-DA and [(99m)Tc]MAMA-HDA were prepared using a ligand-exchange reaction. Biodistribution studies were carried out in normal mice and rats. Then, a high initial uptake of Tc-99m was observed, followed by a rapid clearance from the heart. The maximum heart/blood ratio was 3.6 at 2 min postinjection of [(99m)Tc]MAMA-HDA. These kinetics were similar to those with postinjection of p-[(125)I]iodophenylpentadecanoic acid. Metabolite analysis showed [(99m)Tc]MAMA-HDA was metabolized by beta-oxidation in the body. In conclusion, [(99m)Tc]MAMA-HDA is a promising compound as a long chain fatty acid analogue for estimating beta-oxidation of fatty acid in the heart.

The hole mobility of a discotic liquid-crystalline triphenylene compound is enhanced by the gelation with hydrogen-bonded fibrous aggregates.