188Re complexes based on novel chelators derived from dimercaptosuccinic acid


188Re complexes based on novel chelators derived from dimercaptosuccinic acid

Pietzsch, H.-J.; Heinrich, T.; Kraus, W.; Seifert, S.; Spies, H.

This work is part of our efforts to develop chelating agents for stable binding and easy conjugation of 188Re to biologically interesting structures. Keeping in mind the high in vivo stability of [188ReO(DMSA)2]- [1] we want to exploit this coordination system for the design of 188ReO(V) chelates which are stable towards re-oxidation to perrhenate and towards ligand exchange under all conditions of radiopharmaceutical procedures and applications.
The new type of tetradentate ligand has been synthesized by bridging two molecules of dimercapto-succinic acid (DMSA) with an alkylene triamine chain. The resulting stereo-isomeric tetrathiolato S4 ligand 1 forms five-coordinate oxorhenium(V) complexes by ligand exchange reaction of NBu4[ReOCl4] in methanol. Without addition of base the compounds will be isolated as “betain”, [ReO(S4)], with the protonated nitrogen of the bridge as internal “counter ion”.
The activated BFCA 2 enables easy linking of biomolecules containing a terminal amino group. Prototypic model conjugates with tripeptides have been identified in non-radioactive form by electrospray mass spectrometry.
The 188Re labelling procedure runs fast, in good yields and under mild conditions, making the new complexes interesting as a further access to stable 188Re radio-therapeutics.

  • Lecture (Conference)
    „Radiotracers for In vivo Assessment of Biological Function New Directions“, 22.-23.04.2005, Warschau, Poland

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Publ.-Id: 7326