A seven-coordinate Mn(<scp>ii</scp>) complex with a pyridine-based 15-membered macrocyclic ligand containing one acetate pendant arm: structure, stability and relaxation properties

Pražáková, Marie; Ndiaye, Daouda; Tóth, Éva; Drahoš, Bohuslav

doi:10.1039/d3dt00701d

Cited by 3 publications

(1 citation statement)

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“…9,15 The dissociation of manganese complexes is usually considered to be a proton-and metal-assisted mechanism. 9,11,12,24,26,54 Zinc(II) ions, as the second most abundant trace metal ion in vivo with a similar ion radius to manganese(II), are more suitable for kinetic inertness assessment under near-physiological conditions than other metal ions. 12 Manganese chelates usually have a relatively low transverse relaxivity, while free manganese ions have a considerable transverse relaxivity, so the increase in the transverse relaxation rate can reflect the displacement of manganese(II) ions by zinc(II) ions.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging

Cai,

Jiang,

Cao

et al. 2024

J. Med. Chem.

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Effective vascular and hepatic enhancement and better safety are the key drivers for exploring gadolinium-free hepatobiliary contrast agents. Herein, a facile strategy proposes that the high lipophilicity may be favorable to enhancing sequentially vascular and hepatobiliary signal intensity based on the structure−activity relationship that both hepatic uptake and interaction with serum albumins partly depend on lipophilicity. Therefore, 11 newly synthesized derivatives of manganese ophenylenediamine-N,N,N′,N′-tetraacetic acid (MnLs) were evaluated as vascular and hepatobiliary agents. The maximum signal intensities of the heart, liver, and kidneys were strongly correlated with log P, a key indicator of lipophilicity. The most lipophilic agent, MnL6, showed favorable relaxivity when binding with serum albumin, good vascular enhancement, rapid excretion, and reliable hepatobiliary phases comparable to a classic hepatobiliary agent, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for in vivo liver tumor imaging. Inhibition experiments confirmed the hepatic targeting of MnL6 is mediated by organic anion-transporting polypeptides.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging

Cai,

Jiang,

Cao

et al. 2024

J. Med. Chem.

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A Bis(Aquated) Mn(II)-Based MRI Contrast Agent with a Rigid Hydroquinazoline Unit: Synthesis, Characterization, and in Vivo MR Imaging Study

Mallik,

Saha,

Sarmah

et al. 2024

ACS Appl. Bio Mater.

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Since the finding of nephrogenic systemic fibrosis (NFS) in patients with renal impairment and the long-term accumulation of Gd(III) ions in the central nervous system, the search for nongadolinium ion-based MRI contrast agents made of nutrient metal ions has drawn paramount attention. In this context, the development of Mn(II)-based MRI contrast agents has been a subject of interest for the last few decades. Herein, we report a pentadentate ligand (Li2[BenzPic2]) composed of two picolinate moieties and a rigid 1,2,3,4-tetrahydroquinazoline unit and the corresponding bis(aquated) Mn(II) complex (Complex 1). The complex exhibited high thermodynamic stability (log K cond = 11.62) and kinetic inertness similar to that of the clinically approved Gd(III)-based contrast agent Magnevist. Complex 1 exerted longitudinal relaxivity (r 1) of 5.32 mM–1 s–1 at 1.41 T, 37 °C, pH 7.4, and it increased by 3.6-fold in the presence of serum albumin protein, confirming a substantial rigidifying interaction (albumin association constant K A = 1.66 × 103 M–1) between the protein and the amphiphilic (log P = −0.45) contrast agent. An intravenous dose of 0.08 mmol/kg in a healthy mouse, excellent MRI signal intensity enhancement in the vasculature of the mouse liver, and brightened images of the gallbladder, kidney, and liver were realized.

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Mn-Based MRI Contrast Agents: An Overview

Henoumont,

Devreux,

Laurent

2023

Molecules

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MRI contrast agents are required in the clinic to detect some pathologies, such as cancers. Nevertheless, at the moment, only small extracellular and non-specific gadolinium complexes are available for clinicians. Moreover, safety issues have recently emerged concerning the use of gadolinium complexes; hence, alternatives are urgently needed. Manganese-based MRI contrast agents could be one of these alternatives and increasing numbers of studies are available in the literature. This review aims at synthesizing all the research, from small Mn complexes to nanoparticular agents, including theranostic agents, to highlight all the efforts already made by the scientific community to obtain highly efficient agents but also evidence of the weaknesses of the developed systems.

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A seven-coordinate Mn(ii) complex with a pyridine-based 15-membered macrocyclic ligand containing one acetate pendant arm: structure, stability and relaxation properties

Abstract: A new 15-membered pyridine-based macrocyclic ligand containing one acetate pendant arm (N-carboxymethyl-3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1(18),14,16-triene, L1) was synthesized and its Mn(II) complex MnL1 was investigated in the context of MRI contrast agent development....

Cited by 3 publications

References 53 publications

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging

A Bis(Aquated) Mn(II)-Based MRI Contrast Agent with a Rigid Hydroquinazoline Unit: Synthesis, Characterization, and in Vivo MR Imaging Study

Mn-Based MRI Contrast Agents: An Overview

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