C. Branger, L. Garreau, Y. Frangin
Jul 1, 1995
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Journal
Journal of Labelled Compounds and Radiopharmaceuticals
Abstract
In order to improve the scintigraphy and radiotherapy of neuroendocrine tumors we synthesized two radioiodinated benzylamines [N-(2-chloroethyl)-N-ethyl-2-[ 125 I]iodobenzylamine and N,N-diethyl-2-[ 125 I]iodobenzylamine], analogs of xylamine [N-(2-chloroethyl)-N-ethyl-2-methylbenzylamine]. Xylamine is an irreversible inhibitor of uptake and accumulation of noradrenaline. The two unlabelled iodinated derivatives [N-(2-chloroethyl)-N-ethyl-2-iodobenzylamine and N,N-diethyl-2-iodobenzylamine] were synthesized, purified and checked by HPLC, NMR and mass spectrography. Their affinity for the noradrenaline transporter was determined in vitro on rat brain membrane homogenates with [ 3 H]nisoxetine. Radioiodination was performed by iodide for bromide nucleophilic exchange from brominated precursors. The N,N-diethyl-2-[ 125 I]iodobenzylamine was obtained directly from N,N-diethyl-2-bromobenzylamine. Radiosynthesis of N-(2-chloroethyl)-N-ethyl-2-[[ 125 I]]iodobenzylamine required three steps. A new brominated precursor [N-ethyl-N-(2-bromobenzyl)glycine ethyl ester] which stable for radiolabelling and suitable for reduction to N-(2-hydroxyethyl)-N-ethyl-2-[ 125 I]iodobenzylamine was synthesized. N-(2-hydroxyethyl)-N-ethyl-2-[ 125 I]iodobenzylamine was convertd to N-(2-chloroethyl)-N-ethyl-2-[ 125 I]iodobenzylamine in the presence of an excess of thionyl chloride. Radioiodinated derivatives were purified and checked by HPLC