Both glutamine (Gln) and asparagine (Asn) are key molecules for nitrogen storage and long distance transport in plants. The availability of carbon-11 radiolabeled glutamine (11C-L-Gln) and asparagine (11C-L-Asn) could provide useful tools to non-invasively detect the nitrogen status and the movement of nitrogen-carrying molecules in plants. Based upon a recently published 11C-L-Gln synthesis, we herein report a further optimization for this radiotracer. The nucleophilic cyanide substitution reaction conditions including the reaction temperature, potassium ion source and phase transfer catalyst were systematically investigated. We found that the DMF/KHCO3/18-crown-6/120 oC/5 min is optimal conditions. Under these conditions, 11C-L-Gln was synthesized, typically, in 50% radiochemical yield (decay-corrected) from K11CN, in >95% radiochemical purity, and in more than 95% enantiomeric purity. Relying upon a similar method, 11C-L-Asn was also synthesized.

Convenient radiosynthesis of carbon-11 labeled L-glutamine and L-asparagine for plant imaging

246th National Meeting (2013)

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