Synthesis and characterization of [125I]N-(2-aminoethyl)-4-iodobenzamide as a selective monoamine oxidase B inhibitor.

H Rafii, S Chalon, J E Ombetta, Y Frangin, L Garreau, A M Dognon, I Lena, S Bodard, M P Vilar, J C Besnard

Index: Nucl. Med. Biol. 22(5) , 617-23, (1995)

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Abstract

We described the radiosynthesis of an analog of Ro 16-6491, [125I]N-(2-aminoethyl)-4-iodobenzamide, for SPECT exploration of the monoamine oxidase B (MAO-B) in human brain. The radiolabelling was carried out by nucleophilic exchange of the brominated precursor at solid-state phase in presence of ammonium sulphate. The radiochemical purity of radioiodinated product was higher than 95%. In comparison with Ro 16-6491, the in vitro studies showed a good selectivity of stable N-(2-aminoethyl)-4-iodobenzamide for MAO-B but a slightly lower affinity. Biodistribution studies in the rat showed a high and selective uptake of this compound in the pineal gland 1 h after i.v. injection. The cerebral uptake was low, but the coupling of [125I]N-(2-aminoethyl)-4-iodobenzamide with a lipophilic radical to enhance the passage through the blood-brain barrier can be envisaged.