Synthesis and bio‐evaluation of Tc‐99 m‐labeled fatty acid derivatives for myocardial metabolism imaging

C-11, F-18 and I-123 fatty acids are used for myocardial imaging, and Tc-99m-labeled fatty acids are more desirable substitutes than other radiolabeled fatty acids. In the work reported, [Tc-99m]-CpTT-10-oxo-FPA (1c), [Tc-99m]-CpTT-12-oxo-FPA (2c), [Tc-99m]-CpTT-14- oxo-FPA (3c) and [Tc-99m]-CpTT-16-oxo-FPA (4c) were prepared with 60.76-70.92% of radiochemical yield and purity of more than 95%. These radiotracers (1c, 2c, 3c, 4c) were chemically stable when incubated in Sprague Dawley rat serum for 3 h at 37 degrees C. Tissue distribution studies in female mice indicated that 2c had high initial heart uptake (8.84% ID g(-1) at 1 min postinjection) and 4c had long retention in the heart (1.45% ID g(-1) at 30 min post-injection). Metabolite analysis showed 4c could be metabolized to 5c via beta-oxidation with loss of two -CH2- in the myocardium, the radiometabolite being excreted via urine. However, low heart uptake suggested that 4c cannot be used as a diagnostic imaging agent. Copyright (C) 2016 John Wiley & Sons, Ltd.