Hyperpolarized 13C MRI agents are actively studied for metabolic imaging applications.1 For example, components of citric acid cycle and 2-hydroxyethyl propionate have been used in in vivo imaging and they are prepared by either dynamic nuclear polarization (DNP) or para-hydrogen-induced polarization (PHIP). PHIP is a versatile and cheap method to yield hyperpolarized compounds from substrates containing a moiety that can be hydrogenated. Here we chose to work with amino acid neurotransmitter precursors because amino acids because (1) amino acids � phenylalanine and tryptophan are precursors to neurotransmitters, dopamine and serotonin respectively; (2) radiolabeled aromatic amino acid analogs are used as tracers for tumor imaging.2 Hence we synthesized and hydrogenated 13C-labeled-N-acetyl dehydro amino acids with para-hydrogen (p-H2) to generate 13C-hyperpolarized N-acetyl amino acids. Upon hydrogenation of the double bond with p-H2, hyperpolarization is successfully transferred to the adjacent carbonyl carbon through scalar coupling with newly added protons from p-H2. Our work is the first example of 13C hyperpolarized neurotransmitter precursors.References:(1) Bhattacharya, P.; Chekmenev, E. Y.; Perman, W. H.; Harris, K. C.; Lin, A. P.; Norton, V. A.; Tan, C. T.; Ross, B. D.; Weitekamp, D. P. Journal of Magnetic Resonance 2007 , 186, 150.(2) Jager, P. L.; Vaalburg, W.; Pruim, J.; de Vries, E. G. E.; Langen, K.-J.; Piers, D. A. Journal of Nuclear Medicine 2001 , 42, 432.

Para-hydrogenated neurotransmitter precursors

245th National Meeting (2013)

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