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Development of a reliable remote-controlled synthesis of β-[11C]-5-hydroxy-L-tryptophan on a Zymark robotic system

Neels, O.; Jager, P.; Koopmans, K.; Eriks, E.; de Vries, E.; Kema, I.; Elsinga, P.
Precise staging of neuroendocrine tumors (NET) using positron emission tomography (PET) tracers visualizing their specific metabolic activity is of interest. Besides [18F]FDOPA, staging NET with carbon-11 labeled 5-hydroxytryptophan (5-HTP) is reported in recent literature. We implemented the multi-enzymatic synthesis of enantiomerically pure [11C]-L-5-HTP on a Zymark robotic system to compare both tracers in patient studies. [11C]-5-HTP can be synthesized in up to 24% radiochemical yields (EOB). Average specific activity is 44 000GBq/mmol in ca. 50 min from [11C]methyl iodide in radiochemical purities >99 %. The synthesis of 5-HTP is difficult due to its multi-enzymatic reaction steps but typical yields can be achieved of ca. 400 MBq. [11C]-5-HTP is now reliably used in ongoing studies for staging NET.
Keywords: [11C]-5-HTP; neuroendocrine tumors; robot; carbon-11; enzyme
  • Journal of Labelled Compounds and Radiopharmaceuticals 49(2006)10, 889-895
    DOI: 10.1002/jlcr.1110


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Publ.-Id: 30982