SYNTHESIS AND CHARACTERIZATION OF [I-125] N-(2-AMINOETHYL)-4-IODOBENZAMIDE SELECTIVE AS A MONOAMINE-OXIDASE-B INHIBITOR

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