Stereoisomers of Mn(III) complexes of ethylenebis[(o-hydroxyphenyl)glycine]

Reduction of paraquat-induced renal cytotoxicity by manganese and copper complexes of EGTA and EHPG

“…Some of these beneficial effects of EGTA have been credited to its ability to bind the excess Cu(II) ions which contribute to disease pathology; however, it is now also clear that complexing EGTA with Cu(II) or Mn(II) promotes significant SOD activity [25]. Recently, the related chelating agent EHPG, which is used as a contrast agent for magnetic resonance imaging and as a transferrin mimic in the study of manganese transport [28] and [29], has also been shown to exhibit significant SOD activity when complexed with Mn(II) or Cu(II) [25]. However, the ability of these complexes to reduce paraquat toxicity, in which superoxide generation plays a major part, is not known and formed the basis of this study.…”

“…Another chelator, ethylenebis(hydroxyphenylglycine) (EHPG), which is used as a contrast agent in imaging and as a transferrin mimic in the study of manganese transport [28] and [29], also exhibits SODm properties when complexed with manganese (Mn) (II) or copper (Cu) (II) [25]. A major advantage of the potential use of these agents for the treatment of disease is that EGTA and EHPG have already been used therapeutically [26], [27], [28] and [29]. Furthermore, Mn(II) and Cu(II) complexes of EGTA and EHPG are stable in solution and have a good safety profile in that they do not promote pro-oxidant activities [25].…”

A Janus Chelator Enables Biochemically Responsive MRI Contrast with Exceptional Dynamic Range

“…28,29 The smaller Mn 3+ ion is expected to be 6-coordinate with no inner-sphere water ligand and low relaxivity, analogous to the related [Mn(EHPG)] − complex, Fig S1. 30 …”

“…The Mn 3+ -JED LMCT transitions, Fig S12, reflect those of known Mn 3+ complexes of ligands similar to HBED. 30 …”

Redox-Activated Manganese-Based MR Contrast Agent

“…24-26 By contrast, changing two carboxylato donors to phenolato donors as in HBED or EHPG strongly favors Mn(III) complexes 27,28 with coordination number 6 and no inner-sphere water, Figure 1. 29 We hypothesized that HBET (Figure 1) with a ligand structure that is intermediate between EDTA and HBED – containing only one phenolato donor – could potentially exhibit metastability toward either oxidation state. The preferred oxidation state of such a species would therefore be highly sensitive to changes in redox environment.…”