Radiosynthesis of New Radio Neurotensin (8-13) analogues.

Two types of radiolabelled neurotensin(8-13) analogues have been synthesised. For radioiodination-2- and 4-bromophenyl-acetyl and 2- and 4-bromobenzoyl Arg 8 substituted neurotensin(8-13) were used as substrates for radiolabelling carried out by the Cu 1+ assisted non-isotopic nucleophilic exchange with a labelling yield ranging from 55 to 85% depending on the position of the bromo atom in the phenyl ring. For labelling with 111 In, DTPA was substituted as chelating group on the Arg 8 position of neurotensin(8-13). Labelling was achieved in kit-conditions with a yield of 98%. The non carrier added peptide analogue was recovered by HPLC with a purity > 99% and a specific activity of at least 370 TBq/mmol. The inhibition constant values for the binding of [ 3 H]neurotensin to guinea pig fore brain membranes were of the order of 7.5 nM for the halophenyl compounds and 6.5 nM for the DTPA substituted analogue.