Dong Hyun Kim

16-Cyclopentadienyl Tricarbonyl 99mTc 16-Oxo-hexadecanoic Acid: Synthesis and Evaluation of Fatty Acid Metabolism in Mouse Myocardium†

We synthesized 16-cyclopentadienyl tricarbonyl 99mTc 16-oxo-hexadecanoic acid (99mTc-CpTT-16-oxo-HDA, 1) and investigated its potential as a radiotracer for evaluating fatty acid metabolism in myocardium. Radiotracer 1 was synthesized in 22.6 +/- 6.3% decay-corrected yield by a double ligand transfer reaction between the ferrocene adduct of methyl hexadecanoate ( 2) and Na99mTcO 4 in the presence of Cr(CO)6 and CrCl3, followed by hydrolysis of the methyl ester group. Radiotracer 1 was found to be chemically stable (99% at 6 h) when incubated in human serum. A tissue distribution study in mice showed that high radioactivity accumulated in heart (9.03%ID/g at 1 min and 5.41%ID/g at 5 min postinjection) with rapid clearance and that heart to blood uptake ratios increased with time (2.13 at 5 min and 3.76 at 30 min postinjection). Metabolite analysis of the heart tissues using a simple extraction method showed that 99mTc-CpTT-4-oxo-butyric acid was detected as the major radioactive metabolite by HPLC, suggesting that 1 is metabolized to 99mTc-CpTT-4-oxo-butyric acid via beta-oxidation in myocardium.

Evaluation of 4-[18F]fluoro-1-butyne as a radiolabeled synthon for click chemistry with azido compounds

Click chemistry is a useful approach for the preparation of novel radiopharmaceuticals. In this study, we evaluated 4-[(18)F]fluoro-1-butyne as a radiolabeled synthon for click chemistry with azido compounds. Our results showed that nucleophilic substitution of 4-tosyloxy-1-butyne with K[(18)F]F produces vinyl acetylene as well as 4-[(18)F]fluoro-1-butyne, while the same reaction using 5-tosyloxy-1-pentyne gives exclusively 5-[(18)F]fluoro-1-pentyne. Thus, omega-[(18)F]fluoro-1-alkynes with chain lengths longer than four carbons may be better radiolabeled synthons for use in click chemistry.