Positron labeled antioxidants: synthesis and tissue biodistribution of 6-deoxy-6-[18F]fluoro-L-ascorbic acid

A one-pot synthesis of 6-deoxy-6-[18F]fluoro-L-ascorbic acid (18F-DFA) has been developed via nucleophilic displacement of a cyclic sulfate with no-carrier-added [18F]fluoride ion. Isolated radiochemical yields of around 15% were obtained with radiochemical purity of over 99% after overall synthesis time of 90 min. Tissue distribution studies with 18F-DFA in rats showed high uptake of radioactivity in the adrenals, kidneys, liver and small intestine--organs known to have high concentrations of L-ascorbic acid. The slow and low uptake of radioactivity in the brain was observed between 10 and 120 min after i.v. injection. In vivo behavior of 18F-DFA in mice bearing 3-methylcholanthrene-induced fibrosarcoma demonstrated its ability to accumulate in the tumor.