Synthesis of ¹⁸F-Labeled FC-119S and Its Tosyl Precursor

Area of Science:

• Neuroscience
• Radiochemistry
• Pharmacology

Background:

• Animal models are crucial for Alzheimer's disease (AD) drug development.
• Positron Emission Tomography (PET) visualizes amyloid-beta (Aβ) plaques, a key AD biomarker.
• [18F]FC-119S is a 2-pyridylbenzothiazole analog used as a PET radiotracer for Aβ plaque imaging.

Purpose of the Study:

• To develop an automated synthesis method for 18F-labeled FC-119S.
• To optimize the radiotracer production for use in animal PET studies of AD.
• To improve the purification process for 18F-labeled FC-119S.

Main Methods:

• Automated synthesis of 18F-labeled FC-119S using a tosyl precursor.
• Comparison of mesyl and tosyl precursors for synthesis and purification.
• Semipreparative high-performance liquid chromatography (HPLC) for purification.

Main Results:

• An alternative synthesis using a tosyl precursor successfully delayed the elution of nonfluorinated byproducts.
• 18F-labeled FC-119S was eluted without proximate byproducts during chromatographic purification.
• Routine production of 18F-labeled FC-119S was achieved for AD animal studies.

Conclusions:

• The developed automated synthesis method provides efficient and reliable production of 18F-labeled FC-119S.
• This optimized radiotracer is suitable for routine PET imaging of Aβ plaques in AD animal models.
• The improved purification strategy enhances the quality and usability of the radiotracer for preclinical research.