• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.395-402
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• 2009

Insulin appears to play a role in brain physiology, and disturbances of cerebral insulin signalling and glucose homeostasis are implicated in brain pathology. The objective of the present study was to investigate the protective effects of insulin under conditions of oxidative stress induced by hydrogen peroxide ($H_2O_2$) in C6 glial cells. Insulin at concentration of $10^{-7}$ M could prevent 12 h $H_2O_2$-induced cell death. The formation of reactive oxygen species (ROS), nitric oxide (NO) and 2-thiobarbituric acid-reactive substances (TBARS) were significantly scavenged by insulin pre-treatment in C6 glial cells after $H_2O_2$-induced oxidative stress. Insulin significantly stimulated the phosphorylation of Akt in the cells and the activation of Akt was maintained in response to insulin under $H_2O_2$ incubation for 12 h. In conclusion, these results provide evidence that insulin acts as a free radical scavenger and stimulating Akt activity. These data suggest that insulin may be effective in degenerative diseases with oxidative stress.

• Molecules and Cells
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• v.28 no.6
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• pp.545-551
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• 2009

Mitogen-activated protein kinases (MAPK) affect the activation of activator protein-1 (AP-1), which plays an important role in regulating a range of cellular processes. However, the roles of these signaling factors on hydrogen peroxide ($H_2O_2$)-induced cell death are unclear. This study examined the effects of $H_2O_2$ on the activation of MAPK and AP-1 by exposing the cells to $H_2O_2$ generated by either glucose oxidase or a bolus addition. Exposing BJAB or Jurkat cells to $H_2O_2$ affected the activities of MAPK differently according to the method of $H_2O_2$ exposure. $H_2O_2$ increased the AP-1-DNA binding activity in these cells, where continuously generated $H_2O_2$ led to an increase in mainly the c-Fos, FosB and c-Jun proteins. The c-Jun-$NH_2$-terminal kinase (JNK)-mediated activation of c-Jun was shown to be related to the $H_2O_2$-induced cell death. However, the suppression of $H_2O_2$-induced oxidative stress by either JNK inhibitor or c-Jun specific antisense transfection was temporary in the cells exposed to glucose oxidase but not to a bolus $H_2O_2$. This was associated with the disruption of death signaling according to the severe and prolonged depletion of reduced glutathione. Overall, these results suggest that $H_2O_2$ may decide differently the mode of cell death by affecting the intracellular redox state of thiol-containing antioxidants, and this depends more closely on the duration exposed to $H_2O_2$ than the concentration of this agent.

• Korean Journal of Clinical Laboratory Science
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• v.41 no.2
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• pp.83-92
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• 2009

This study was undertaken to examine the effect of oxidants on membrane transport function in renal epithelial cells. Hydrogen peroxide ($H_2O_2$) was used as a model oxidant and the membrane transport function was evaluated by measuring $Na^+$-dependent phosphate ($Na^+$-Pi) uptake in opossum kidney (OK) cells. $H_2O_2$ inhibited $Na^+$-Pi uptake in a dose-dependent manner. The oxidant also caused loss of cell viability in a dose-dependent fashion. However, the extent of inhibition of the uptake was larger than that in cell viability. $H_2O_2$ inhibited $Na^+$-dependent uptake without any effect on $Na^+$-independent uptake. $H_2O_2$-induced inhibition of $Na^+$-Pi uptake was prevented completely by catalase, dimethylthiourea, and deferoxamine, suggesting involvement of hydroxyl radical generated by an iron-dependent mechanism. In contrast, antioxidants Trolox, N,N'-diphenyl-p-phenylenediamine, and butylated hydroxyanisole did not affect the $H_2O_2$ inhibition. Kinetic analysis indicated that $H_2O_2$ decreased Vmax of $Na^+$-Pi uptake with no change in the Km value. Phosphonoformic acid binding assay did not show any difference between control and $H_2O_2$-treated cells. $H_2O_2$ also did not cause degradation of $Na^+$-Pi transporter protein. Reduction in $Na^+$-Pi uptake by $H_2O_2$ was associated with ATP depletion and direct inhibition of $Na^+$-$K^+$-ATPase activity. These results indicate that the effect of $H_2O_2$ on membrane transport function in OK cells is associated with reduction in functional $Na^+$-pump activity. In addition, the inhibitory effect of $H_2O_2$ was not associated with lipid peroxidation.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.1982-1991
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• 2018

Ethanol accumulation inhibited the growth of Saccharomyces cerevisiae during wine fermentation. Autophagy and the release of reactive oxygen species (ROS) were also induced under ethanol stress. However, the relation between autophagy and ethanol stress was still unclear. In this study, expression of the autophagy genes ATG1 and ATG8 and the production of ROS under ethanol treatment in yeast were measured. The results showed that ethanol stress very significantly induced expression of the ATG1 and ATG8 genes and the production of hydrogen peroxide ($H_2O_2$) and superoxide anion (${O_2}^{{\cdot}_-}$). Moreover, the atg1 and atg8 mutants aggregated more $H_2O_2$ and ${O_2}^{{\cdot}_-}$ than the wild-type yeast. In addition, inhibitors of the ROS scavenging enzyme induced expression of the ATG1 and ATG8 genes by increasing the levels of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. In contrast, glutathione (GSH) and N-acetylcystine (NAC) decreased ATG1 and ATG8 expression by reducing $H_2O_2$ and ${O_2}^{{\cdot}_-}$ production. Rapamycin and 3-methyladenine also caused an obvious change in autophagy levels and simultaneously altered the release of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. Finally, inhibitors of the mitochondrial electron transport chain (mtETC) increased the production of $H_2O_2$ and ${O_2}^{{\cdot}_-}$ and also promoted expression levels of the ATG1 and ATG8 genes. In conclusion, ethanol stress induced autophagy which was regulated by $H_2O_2$ and ${O_2}^{{\cdot}_-}$ derived from mtETC, and in turn, the autophagy contributed to the elimination $H_2O_2$ and ${O_2}^{{\cdot}_-}$.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.35-38
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• 2012

Room temperature oxidation of organic sulfides with polyvinylpyrrolidone-supported hydrogen peroxide (PVP-$H_2O_2$) in the presence of Mn(III) complexes of meso-tetraphenylporphyrin, Mn(TPP)X (X = OCN, SCN, OAc, Cl) and imidazole (ImH) leads to the highly chemoselective (ca. 90%) oxidation of sulfides to the corresponding sulfoxide. The efficiency of reaction has been shown to be influenced by different reaction parameters such as the nature of counterion (X) and solvent as well as the molar ratio of reactants. Using Mn(TPP)OCN and ImH in 1:15 molar ratio and acetone as the solvent leads to the efficient oxidation of different sulfides.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.251-254
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• 1989

A kinetic study on the chemiluminescence resulting from the reaction between bis(2,4-dinitrophenyl) oxalate(DNPO) and hydrogen peroxide in the presence of fluorescent polycyclic aromatic hydrocarbons in a viscous phthalate medium has been conducted. The resultant data confirm that the reaction between DNPO and $H_2O_2$ is the rate determining step. Higher rate constants are obtained with DNPO than those with bis(2,4,6-trichlorophenyl) oxalate (TCPO).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4B
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• pp.377-382
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• 2011

In this study, hydrogen peroxide is stabilized in modified Fenton reaction to improve the soil remediation. Phenanthrene, which is the typical compound in PAHs, was spiked into soil samples to copy the original contaminated site. Anionic surfactant, SDS (Sodium dodecyl sulfate) was used for hydrogen peroxide stabilizer. 4 mM of Fe(II), 5~50 mM of SDS and 102.897 mM of $H_2O_2$ was injected into soil samples which is contaminated by 125 mg/kg of phenanthrene to analyze decomposition rate of phenanthrene in modified Fenton reaction. In condition which SDS was injected 30 mM, decomposition rate of phenanthrene has best efficiency as 95% and in condition which SDS was injected over 30 mM, decomposition rate is lower than SDS 30 mM because SDS enacted as scavenger in the system. Results which assess the change of hydrogen peroxide concentration after injecting hydrogen peroxide stabilizer showed that hydrogen peroxide concentration was 14.6995 mM so that is stabilized at Fe(II) 2 mM condition in 48 hours. On the other hand, hydrogen peroxide is not stable in Fe(III) condition. SDS concentration was fixed and iron concentration was changed 2~8 mM to find out optimize proportion between iron concentration and SDS concentration in modified Fenton reaction. Consequentially, in condition of which Fe(II) 4 mM and SDS 30 mM, reaction has the highest removal rate as 95%.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.2
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• pp.215-223
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• 2018

Intracellular $Ca^{2+}$ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide ($H_2O_2$) on cytosolic $Ca^{2+}$ accumulation in mouse parotid acinar cells. Intracellular $Ca^{2+}$ levels were slowly elevated when $1mM\;H_2O_2$ was perfused in the presence of normal extracellular $Ca^{2+}$. In a $Ca^{2+}-free$ medium, $1mM\;H_2O_2$ still enhanced the intracellular $Ca^{2+}$ level. $Ca^{2+}$ entry tested using manganese quenching technique was not affected by perfusion of $1mM\;H_2O_2$. On the other hand, $10mM\;H_2O_2$ induced more rapid $Ca^{2+}$ accumulation and facilitated $Ca^{2+}$ entry from extracellular fluid. $Ca^{2+}$ refill into intracellular $Ca^{2+}$ store and inositol 1,4,5-trisphosphate ($1{\mu}M$)-induced $Ca^{2+}$ release from $Ca^{2+}$ store was not affected by $1mM\;H_2O_2$ in permeabilized cells. $Ca^{2+}$ efflux through plasma membrane $Ca^{2+}-ATPase$ (PMCA) was markedly blocked by $1mM\;H_2O_2$ in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected $H_2O_2-induced$ $Ca^{2+}$ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of $H_2O_2$ under pathological conditions may lead to cytosolic $Ca^{2+}$ accumulation and that the primary mechanism of $H_2O_2-induced$ $Ca^{2+}$ accumulation is likely to inhibit $Ca^{2+}$ efflux through PMCA rather than mobilize $Ca^{2+}$ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.3
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• pp.195-200
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• 2022

Sulfur is an essential element in plants, including amino acids, vitamin synthesis, and acting as an antioxidant. However, the interaction between endogenous sulfur and proline synthesis has not been yet fully documented. White clover (Trifolium repens L.) is known as a species highly sensitive to sulfate supply. Therefore, this study aimed to elucidate the role of sulfur in regulating proline metabolism in relation to ammonia detoxification and hydrogen peroxide (H₂O₂) accumulation in white clover. The detached leaves of white clover were immersed in solution containing different concentration of sulfate (0, 10, 100, and 1000 mM MgSO₄). As MgSO₄ concentrations were increased, the concentration of H₂O₂ increased up to 2.5-fold compared to control, accompanied with H₂O₂ detection in leaves. Amino acid concentrations significantly increased only at higher levels (100 and 1000 mM MgSO₄). No significant difference was observed in protein concentration. Proline and ∆^1-pyrroline-5-carboxylate (P5C) concentrations slightly decreased at 10 and 100 mM MgSO₄ treatments, whereas it rapidly increased over 1.9-fold at 1000 mM MgSO₄ treatment. Ammonia concentrations gradually increased up to 8.6-fold. These results indicate that exogenous sulfur levels are closely related to H₂O₂ and ammonia synthesis but affect proline biosynthesis only at a higher level.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1361-1362
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• 2007

There is great interest in the applicability of electrogenerated hydrogen peroxide to a wide variety of industrial processes, usually involving oxidation of organics. Hydrogen peroxide is now employed for the bleaching of mechanical pulp and the bleaching of chemical pulp in the pulp and paper industry, thus displacing the traditional alkaline treatments with chlorine-based chemicals. This psper reperts a comparative study of $H_{2}O_{2}$ electogeneration on gas-diffusion electrode in divided cell with several $Nafion^{(R)}$ protonexchange membranes, Russian cation-exchange membrane MK-40 and SPEEK membrane. The influence of different PEMs on electrochemical cell voltage, current efficiency and energy consumption of hydrogen peroxide electrogeneration has been stadied.