title: DOTAM-type ligands possessing arginine pendant groups for use in PARACEST MRI.
abstract: A synthetic methodology was developed for the preparation of metal-chelating ligands that possess arginine pendant groups relying on the alkylation of 1,4,7,10-tetraazacyclododecane (cyclen) with arginine-containing electrophiles. Conditions for the selective trialkylation or peralkylation of cyclen are described, the outcome being dependent on the nature of the arginine-derived electrophile and the solvent used for the reaction. Lanthanide metal complexes of the ligands prepared by the described route were evaluated for their suitability as PARACEST contrast agents for use in magnetic resonance imaging. The Dy(3+) and Tm(3+) complexes display CEST effects that are associated with the amide protons proximate to the metal center. These signals exhibit pH dependence in the range of 6.0-8.0 and thus may have the potential for pH measurement in physiological range.
authors: Department of Chemistry, The University of Western Ontario, London, ON, Canada, N6A 5B7.
authors: Mojmír
authors: M
authors: Suchý
authors: Alex X
authors: AX
authors: Li
authors: Mark
authors: M
authors: Milne
authors: Robert
authors: R
authors: Bartha
authors: Robert H E
authors: RH
authors: Hudson
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D001120:Arginine / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D000080027:Cyclams; D006571:Heterocyclic Compounds / Q000737:chemistry; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D028581:Lanthanoid Series Elements; D008024:Ligands; D008279:Magnetic Resonance Imaging
chemical_list: C522450:1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane; D000081:Acetamides; D002614:Chelating Agents; D003287:Contrast Media; D056831:Coordination Complexes; D000080027:Cyclams; D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; D028581:Lanthanoid Series Elements; D008024:Ligands; D001120:Arginine; C038072:cyclen