1. Automated synthesis of 18F-fluoropropoxytryptophan for amino acid transporter system imaging.
- Author
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Shih IH, Duan XD, Kong FL, Williams MD, Yang K, Zhang YH, and Yang DJ
- Subjects
- Animals, Cell Line, Tumor, Heterografts, Humans, Male, Mice, Neoplasm Transplantation, Prostatic Neoplasms metabolism, Radiography, Fluorine Radioisotopes pharmacology, Positron-Emission Tomography, Prostatic Neoplasms diagnostic imaging, Radiopharmaceuticals chemical synthesis, Radiopharmaceuticals chemistry, Radiopharmaceuticals pharmacology, Tryptophan analogs & derivatives, Tryptophan chemical synthesis, Tryptophan chemistry, Tryptophan pharmacology
- Abstract
Objective: This study was to develop a cGMP grade of [(18)F]fluoropropoxytryptophan ((18)F-FTP) to assess tryptophan transporters using an automated synthesizer., Methods: Tosylpropoxytryptophan (Ts-TP) was reacted with K(18)F/kryptofix complex. After column purification, solvent evaporation, and hydrolysis, the identity and purity of the product were validated by radio-TLC (1M-ammonium acetate : methanol = 4 : 1) and HPLC (C-18 column, methanol : water = 7 : 3) analyses. In vitro cellular uptake of (18)F-FTP and (18)F-FDG was performed in human prostate cancer cells. PET imaging studies were performed with (18)F-FTP and (18)F-FDG in prostate and small cell lung tumor-bearing mice (3.7 MBq/mouse, iv)., Results: Radio-TLC and HPLC analyses of (18)F-FTP showed that the Rf and Rt values were 0.9 and 9 min, respectively. Radiochemical purity was >99%. The radiochemical yield was 37.7% (EOS 90 min, decay corrected). Cellular uptake of (18)F-FTP and (18)F-FDG showed enhanced uptake as a function of incubation time. PET imaging studies showed that (18)F-FTP had less tumor uptake than (18)F-FDG in prostate cancer model. However, (18)F-FTP had more uptake than (18)F-FDG in small cell lung cancer model., Conclusion: (18)F-FTP could be synthesized with high radiochemical yield. Assessment of upregulated transporters activity by (18)F-FTP may provide potential applications in differential diagnosis and prediction of early treatment response.
- Published
- 2014
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