1 research outputs found
Synthesis of <sup>11</sup>C‑Labeled Thiamine and Fursultiamine for in Vivo Molecular Imaging of Vitamin B<sub>1</sub> and Its Prodrug Using Positron Emission Tomography
To enable in vivo analysis of the
kinetics of vitamin B<sub>1</sub> (thiamine) and its derivatives by
positron emission tomography (PET), <sup>11</sup>C-labeled thiamine
([<sup>11</sup>C]-<b>1</b>) has
been synthesized. This was carried out via a rapid, multistep synthesis
consisting of Pd<sup>0</sup>-mediated <i>C</i>-[<sup>11</sup>C]Âmethylation of a thiazole ring for 3 min and benzylation with 5-(bromomethyl)Âpyrimidine
for 7 min. The [<sup>11</sup>C]-<b>1</b> was also converted
to <sup>11</sup>C-labeled fursultiamine ([<sup>11</sup>C]-<b>2</b>), a prodrug of vitamin B<sub>1</sub>, by disulfide formation with <i>S</i>-tetrahydrofurfurylthiosulfuric acid sodium salt. Characterization
of [<sup>11</sup>C]-<b>1</b> and [<sup>11</sup>C]-<b>2</b> showed them to be suitable for use as PET probes for in vivo pharmacokinetic
and medical studies. The total durations of the preparations of [<sup>11</sup>C]-<b>1</b> and [<sup>11</sup>C]-<b>2</b> were
shorter than 60 and 70 min, respectively. The [<sup>11</sup>C]ÂCH<sub>3</sub>I-based decay-corrected radiochemical yields of [<sup>11</sup>C]-<b>1</b> and [<sup>11</sup>C]-<b>2</b> were 9–16%
and 4–10%, respectively. The radioactivities of the final injectable
solutions of [<sup>11</sup>C]-<b>1</b> and [<sup>11</sup>C]-<b>2</b> were 400–700 and 100–250 MBq, respectively.
The radiochemical purity of both [<sup>11</sup>C]-<b>1</b> and
[<sup>11</sup>C]-<b>2</b> was 99%, and the chemical purities
of [<sup>11</sup>C]-<b>1</b> and [<sup>11</sup>C]-<b>2</b> were 99% and 97–99%, respectively. In vivo PET imaging of
normal rats was illustrated by the distribution of [<sup>11</sup>C]-<b>1</b> and [<sup>11</sup>C]-<b>2</b> following intravenous
injection