Different Antioxidant Efficacy of Two MnII-Containing Superoxide Anion Scavengers on Hypoxia/Reoxygenation-Exposed Cardiac Muscle Cells

Abstract

Oxidative stress due to excess superoxide anion ( ) produced by dysfunctional mitochondria is a key pathogenic event of aging and ischemia-reperfusion diseases. Here, a new -scavenging Mn II complex with a new polyamino-polycarboxylate macrocycle (4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diacetate) containing 2 quinoline units (MnQ2), designed to improve complex stability and cell permeability, was compared to parental Mn II complex with methyls replacing quinolines (MnM2). MnQ2 was more stable than MnM2 (log K = 19.56(8) vs. 14.73(2) for the equilibrium Mn 2+ + L 2− , where L = Q2 and M2) due to the involvement of quinoline in metal binding and to the hydrophobic features of the ligand which improve metal desolvation upon complexation. As oxidative stress model, H9c2 rat cardiomyoblasts were subjected to hypoxia-reoxygenation. MnQ2 and MnM2 (10 μmol L −1 ) were added at reoxygenation for 1 or 2 h. The more lipophilic MnQ2 showed more rapid cell and mitochondrial penetration than MnM2. Both MnQ2 and MnM2 abated endogenous ROS and mitochondrial , decreased cell lipid peroxidation, reduced mitochondrial dysfunction, in terms of efficiency of the respiratory chain and preservation of membrane potential (Δψ) and permeability, decreased the activation of pro-apoptotic caspases 9 and 3, and increased cell viability. Of note, MnQ2 was more effective than MnM2 to exert cytoprotective anti-oxidant effects in the short term. Compounds with redox-inert Zn II replacing the functional Mn II were ineffective. This study provides clues which further our understanding of the structure-activity relationships of Mn II -chelates and suggests that Mn II -polyamino-polycarboxylate macrocycles could be developed as new anti-oxidant drugs.

Human Relaxin-2 (Serelaxin) Attenuates Oxidative Stress in Cardiac Muscle Cells Exposed In Vitro to Hypoxia–Reoxygenation. Evidence for the Involvement of Reduced Glutathione Up-Regulation

“…Mitochondrial permeability by transition pore opening is an index of mitochondrial dysfunction and early apoptosis. This was measured by the calcein fluorescence method [ 25 ], based on the principle that the fluorescent probe calcein-AM readily enters into cells and emits fluorescence upon de-esterification. The co-loading of cells with cobalt chloride, which cannot cross the mitochondrial membranes in living cells, quenches calcein fluorescence in the whole cell except mitochondria.…”

Selective protection of human cardiomyocytes from anthracycline cardiotoxicity by small molecule inhibitors of MAP4K4

“…As a starting point, initial proof-of-concept experiments were undertaken in rat H9c2 cardiomyocytes 20 , a low-cost, tractable model used most typically in toxicology research and early-stage cardiac drug discovery. Notably, this body of work includes more than 300 studies of anthracycline toxicity [21][22][23][24][25][26][27][28][29][30][31][32][33][34] as well as high-throughput, phenotypedriven screens for novel cardioprotective agents 35,36 . Viability as measured by the CellTiter-Glo ATP generation assay was markedly impaired by DOX, with half-maximal effects at 150-250 nM at 24 and 48 h (Fig.…”

“…Despite the widely reported utility of H9c2 cells [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] , their applicability as a predictive model in cardiac drug development is compromised by their continuous proliferation, lack of the sodium/calcium exchanger NCX1, lack of beating, and skeletal muscle potential 20,38,39 . Moreover, explicit disparities have been reported in drug effects relating to cardioprotection and cardiotoxicity in this model, compared with human cells 40,41 .…”

Switching on the Fluorescence Emission of Polypyridine Ligands by Simultaneous Zinc(II) Binding and Protonation

“…Potentiometric measurements : Protonation and metal ion coordination with L1 and L2 were studied, determining the corresponding equilibrium constants, in 0.1 M NaCl aqueous solution at 298±0.1 K with previously reported equipment and methods . The reference electrode was an Ag/AgCl electrode in saturated KCl solution, while the hydrogen concentration probe was a glass electrode, calibrated by titrating known amounts of HCl with CO 2 ‐free NaOH solutions.…”