title: Novel 3+1 mixed-ligand Technetium-99m complexes carrying dipeptides as monodentate ligands.
abstract: Novel mixed ligand oxotechnetium complexes of the type [99mTcO(SSS)(SR)], in which the SR monodentate ligand is derived from dipeptides gly-gly, phe-gly and ala-gly, have been synthesized. These complexes, which have a molecular weight above 300, a lipophilic moiety, [TcO(SSS)]+, and an ionizable group separated from the lipophilic moiety by a spacer, have been obtained in 70-95% radiochemical yield. These compounds were prepared using 99mTc-tartrate as the precursor and Sn2+ as the reducing agent. The identity of the [99mTcO(SSS)(SR)] complexes has been established by HPLC comparison with the analogous oxorhenium complexes. The nature of the monodentate co-ligand strongly affects the stability of the 99mTc-complexes and their biodistribution. Complex 3b is the most stable in vitro presenting the highest blood clearance, a high liver uptake and a selective hepatobiliary excretion (54.5% ID at 15 min post-injection, and 69.3% ID at 60 min post injection). The results obtained show that 3b have reasonable stability and in vivo properties that may be useful for peptide labeling.
authors.affiliation: Departamento de Química, ITN, Estrada Nacional 10, 2686-953 Sacavém, Codex, Portugal. celiaf@itn.mces.pt
authors.forename: Célia
authors.initials: C
authors.lastname: Fernandes
authors.forename: Luciana
authors.initials: L
authors.lastname: Patrício
authors.forename: Rui
authors.initials: R
authors.lastname: Moreira
authors.forename: Guilhermina
authors.initials: G
authors.lastname: Cantinho
authors.forename: Helena
authors.initials: H
authors.lastname: Pena
authors.forename: Paula C
authors.initials: PC
authors.lastname: Campello
authors.forename: Isabel
authors.initials: I
authors.lastname: Santos
mesh_terms: D000818:Animals; D004151:Dipeptides / Q000737:chemistry / Q000493:pharmacokinetics*; D004355:Drug Stability; D005260:Female; D007553:Isotope Labeling; D008024:Ligands; D008657:Metabolic Clearance Rate; D051379:Mice; D009928:Organ Specificity; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics; D013667:Technetium / Q000737:chemistry / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D004151:Dipeptides; D008024:Ligands; D019275:Radiopharmaceuticals; D013667:Technetium