Premium
Unprecedented Kinetic Inertness for a Mn 2+ ‐Bispidine Chelate: A Novel Structural Entry for Mn 2+ ‐Based Imaging Agents
Author(s) -
Ndiaye Daouda,
Sy Maryame,
Pallier Agnès,
Même Sandra,
Silva Isidro,
Lacerda Sara,
at Aline M.,
Charbonnière Loïc J.,
Tóth Éva
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202003685
Subject(s) - chelation , chemistry , dissociation (chemistry) , ligand (biochemistry) , biocompatible material , kinetic energy , crystallography , nuclear chemistry , inorganic chemistry , receptor , biomedical engineering , biochemistry , medicine , physics , quantum mechanics
The search for more biocompatible alternatives to Gd 3+ ‐based MRI agents, and the interest in 52 Mn for PET imaging call for ligands that form inert Mn 2+ chelates. Given the labile nature of Mn 2+ , high inertness is challenging to achieve. The strongly preorganized structure of the 2,4‐pyridyl‐disubstituted bispidol ligand L 1 endows its Mn 2+ complex with exceptional kinetic inertness. Indeed, MnL 1 did not show any dissociation for 140 days in the presence of 50 equiv. of Zn 2+ (37 °C, pH 6), while recently reported potential MRI agents MnPyC3A and MnPC2A‐EA have dissociation half‐lives of 0.285 h and 54.4 h under similar conditions. In addition, the relaxivity of MnL 1 (4.28 m m −1 s −1 at 25 °C, 20 MHz) is remarkable for a monohydrated, small Mn 2+ chelate. In vivo MRI experiments in mice and determination of the tissue Mn content evidence rapid renal clearance of MnL 1 . Additionally, L 1 could be radiolabeled with 52 Mn and the complex revealed good stability in biological media.