• Parasites, Hosts and Diseases
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• v.51 no.1
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• pp.61-68
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• 2013

Entamoeba histolytica, which causes amoebic colitis and occasionally liver abscess in humans, is able to induce host cell death. However, signaling mechanisms of colon cell death induced by E. histolytica are not fully elucidated. In this study, we investigated the signaling role of NOX in cell death of HT29 colonic epithelial cells induced by E. histolytica. Incubation of HT29 cells with amoebic trophozoites resulted in DNA fragmentation that is a hallmark of apoptotic cell death. In addition, E. histolytica generate intracellular reactive oxygen species (ROS) in a contact-dependent manner. Inhibition of intracellular ROS level with treatment with DPI, an inhibitor of NADPH oxidases (NOXs), decreased Entamoebainduced ROS generation and cell death in HT29 cells. However, pan-caspase inhibitor did not affect E. histolytica-induced HT29 cell death. In HT29 cells, catalytic subunit NOX1 and regulatory subunit Rac1 for NOX1 activation were highly expressed. We next investigated whether NADPH oxidase 1 (NOX1)-derived ROS is closely associated with HT29 cell death induced by E. histolytica. Suppression of Rac1 by siRNA significantly inhibited Entamoeba-induced cell death. Moreover, knockdown of NOX1 by siRNA, effectively inhibited E. histolytica-triggered DNA fragmentation in HT29 cells. These results suggest that NOX1-derived ROS is required for apoptotic cell death in HT29 colon epithelial cells induced by E. histolytica.

• The Journal of Internal Korean Medicine
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• v.31 no.4
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• pp.693-705
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• 2010

Objectives : The water extract of Daechilgi-tang(DCGT) has traditionally been used for treatment of qi stagnation(氣滯), which is considered to be one of the important causes of neuronal disease in oriental medicine. However, little is known about the mechanism by which DCGT protects neuronal cells from brain cell damages. Methods and Results : The author tested the mechanism of the cytoprotective effect of DCGT on glutamate -stimulated rat C6 glial cells. DCGT significantly protected C6 glial cells from glutamate in MTT assay. Pre-treatment of C6 glial cells with DCGT markedly inhibited the DNA fragmentation of C6 cells induced by glutamate. Glutamate increased the generation of reactive oxygen species(ROS) and intracellular calcium level in C6 glial cells. However, pre-treatment with DCGT markedly suppressed the increase of ROS generation and intracellular calcium accumulation induced by glutamate. Among apoptosis signaling mediators, DCGT markedly increased the expression level of Bcl2 in glutamate-treated cells. It also inhibited the cleavage of caspase-3 and PARP proteins by glutamate in C6 glial cells. Conclusions : These results suggest that DCGT protects brain cells from glutamate cytotoxicity through inhibition of ROS generation and activation of apoptosis signaling pathway as well as induction of the anti-oxidant system.

• Toxicological Research
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• v.27 no.3
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• pp.161-166
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• 2011

Carbon black, a particulate form of pure elemental carbon, is an industrial chemical with the high potential of occupational exposure. Although the relationship between exposure to particulate matters (PM) and cardiovascular diseases is well established, the cardiovascular risk of carbon black has not been characterized clearly. In this study, the cytotoxicity of carbon black to vascular smooth muscle and endothelial cells were examined to investigate the potential vascular toxicity of carbon black. Carbon black with distinct particle size, N330 (primary size, 28~36 nm) and N990 (250~350 nm) were treated to A-10, rat aortic smooth muscle cells and human umbilical vein endothelial cell line, ECV304, and cell viability was assessed by lactate dehydrogenase (LDH) leakage assay. Treatment of carbon black N990 resulted in the significant reduction of viability in A-10 cells at 100 ${\mu}g$/ml, the highest concentration tested, while N330 failed to cause cell death. Cytotoxicity to ECV304 cells was induced only by N330 at higher concentration, 200 ${\mu}g$/ml, suggesting that ECV304 cells were relatively resistant to carbon black. Treatment of 100 ${\mu}g$/ml N990 led to the elevation of reactive oxygen species (ROS) detected by dichlorodihydrofluorescein (DCF) in A-10 cells. Pretreatment of antioxidants, N-acetylcysteine (NAC) and sulforaphane restored decreased viability of N990-treated A-10 cells, and N-acetylcysteine, but not sulforaphane, attenuated N990-induced ROS generation in A-10 cells. Taken together, present study shows that carbon black is cytotoxic to vascular cells, and the generation of reactive oxygen contributes to the development of cytotoxicity. ROS scavenging antioxidant could be a potential strategy to attenuate the toxicity induced by carbon black exposure.

• The Journal of Korean Medicine
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• v.28 no.1 s.69
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• pp.137-147
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• 2007

Objective : The objective of this study was to investigate the antioxidative effects of Carthami Flos extract. Methods : Total antioxidant status was examined by total antioxidant capacity(TAC) and total antioxidant response(TAR) against potent free radical reactions. The effect of Carthami Flos extract was examined far details of total phenolic content concentration at which 1,1-dipheny1-2-picrylhydrazyl(DPPH) radical scavenging activity was inhibited, the inhibitory effect on lipid peroxidation, and the effect on reactive oxygen species(ROS) generation. Results : TAC of Carthami Flos extract at the concentration of 5 mg/ml was 1.84 mM Trolox equivalent. 2. TAR of Carthami Flos extract, on the other hand, couldn't be determined due to interference from unidentified compounds. 3. Total phenolic content of Carthami Flos extract at the concentration of 5 mg/ml was 2.01 mM gallic acid equivalent. 4. Concentration of Carthami Flos extract at which DPPH radical scavenging activity was inhibited by 50% was 6.43 mg/ml as compared to 100% by Pyrogallol solution as a reference. 5. The inhibitory effect of the extract on lipid peroxidation was examined using rat liver mitochondria induced by FeS04/ascorbic acid. Carthami Flos extract at the concentration of 10 ms/ml slightly but significantly decreased TBARS concentration. The extract continued to prevent lipid peroxidation in a dose-dependent manner. 6. The effect of Carthami Flos extract on reactive oxygen species(ROS) generation was examined using a cell-free system induced by hydrogen peroxide/FeS04. Addition of 1 mg/ml of Carthami Flos extract significantly reduced dichlorofluorescein(DCF) fluorescence. Carthami Flos extract caused concentration-dependent attenuation of the increase in DCF fluorescence, indicating that the ektract significantly prevented ROS generation in vitro. Conclusion: : Antioxidant efffcts of Carffami ffor extract seem to be due, at least in part, to the prevention offree radical-induced oxidation, fellowed by inhibition of lipid peroxidation.

• The Journal of Korean Medicine
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• v.28 no.1 s.69
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• pp.148-158
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• 2007

Objective : The objective of this study was to investigate the antioxidant effects of Mori Folium extract. Methods Total antioxidant status was examined by total antioxidant capacity(TAC) and total antioxidant response(TAR) against potent free radical reactions. The effect of Mori Folium extract was examined by measuring total phenolic content, concentration at which 1,1-dipheny1-2-picrylhydrazyl(DPPH) radical scavenging activity was inhibited, inhibitory effect on lipid peroxidation, and the effect on reactive oxygen species(ROS) generation. Results : 1. TAC and TAR of Mori Folium extract at the concentration of 5 mg/ml were 1.61 and 1.24 mM Trolox equivalents, respectively. 2. Total phenolic content of Mori Folium extract at the concentration of 5 mg/Ml was 1.70 mM gallic acid equivalent. 3. Concentration of Mori Folium extract at which DPPH radical scavenging activity was inhibited by 50% was 2.29 m9/m4 as compared to 100% by Pyrogallol solution as a reference. 4. The inhibitory effect of the extract on lipid peroxidation was examined using rat liver mitochondria induced by FeSO$_4$/ascorbic acid. Mori Folium extract at the concentration of 10 mg/ml significantly decreased thiobarbituric acid reactive substances(TBARS) concentration. The extract prevented lipid peroxidation in a dose-dependent 5. The effect of Mori Folium extract on reactive oxygen species(ROS) generation was examined using a celt-free system induced by hydrogen peroxide FeSO$_4$. Addition of 1 mg/ml of Mori Folium extract significantly reduced dichlorofluorescein(DCf) fluorescence. The extract caused concentration-dependent attenuation of the increase in DCF fluorescence, indicating that the extract significantly prevented ROS generation in vitro. Conclusion ; The antioxidant effects of Mori Folium extract seem to be due, at least in part, to the prevention offree radical-induced oxidation, fllowed by inhibition of lipid peroxidation.

• Journal of Life Science
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• v.28 no.8
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• pp.892-899
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• 2018

Portulaca oleracea L. is an edible plant widely consumed in daily diet throughout Europe, Asia and America. In this study, protective effects of P. oleracea L. extracts against oxidative stress and matrix metalloproteinase (MMP) activity induced by ultraviolet B (UVB) radiation were investigated using HaCaT immortal human keratinocytes. In this context, the mRNA and protein productions of MMPs (MMP-1, -2, and -9) and type I procollagen, which are major markers of photoaging induced by UVB radiation in HaCaT keratinocytes, were evaluated. Furthermore, UVB-induced reactive oxygen species (ROS) generation and mRNA and protein expression levels of superoxide dismutase-1 (SOD-1), oxygenase-1 (OH-1), and nuclear factor-erythroid 2-related factor-2 (Nrf-2), all of which are associated with the antioxidant balance, were investigated. As shown by the results, UVB radiation induced ROS formation and led to increased production of MMPs and decreased collagen production in human keratinocytes, which resulted in skin photoaging or photodamage. The treatment with P. oleracea L. extracts downregulated MMP (MMP-1, -2, and -9) production and upregulated type I procollagen expression in UVB-induced HaCaT cells. Furthermore, treatment with the extracts decreased UVB-induced ROS generation and increased the expression of antioxidant enzymes, such as SOD-1 and OH-1, through the Nrf-2 pathway. Taken together, these results suggest that P. oleracea L. extracts could be a potential cosmeceutical agent for the prevention of skin photoaging or photodamage.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.206-207
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• 2001

Cochlodinium polykrikoides is one of the most harmful red tide dinoflagellates and is highly toxic to fish. Red tides due to this dinoflagellate have been reported in Korea, Japan, and other countries, and frequently cause severe damage to fish farming. Recently study has suggested that C. polykrikoides generates reactive oxygen species (ROS) such as superoxide anion ($O_{2-}$) and hydrogen peroxide ($H_2O_2$), and the ROS-mediated ichthyotoxicity has been proposed. (omitted)

• BMB Reports
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• v.46 no.4
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• pp.225-229
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• 2013

Methylglyoxal (MG) is an endogenous metabolite which is present in increased concentrations in diabetics and reacts with amino acids to form advanced glycation end products. In this study, we investigated whether ferritin enhances DNA cleavage by the reaction of MG with lysine. When plasmid DNA was incubated with MG and lysine in the presence of ferritin, DNA strand breakage was increased in a dose-dependent manner. The ferritin/MG/lysine system-mediated DNA cleavage was significantly inhibited by reactive oxygen species (ROS) scavengers. These results indicated that ROS might participate in the ferritin/MG/lysine system-mediated DNA cleavage. Incubation of ferritin with MG and lysine resulted in a time-dependent release of iron ions from the protein molecules. Our data suggest that DNA cleavage caused by the ferritin/MG/lysine system via the generation of ROS by the Fenton-like reaction of free iron ions released from oxidatively damaged ferritin.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.583-590
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• 2019

As the consumption of fresh fruits and vegetables increases, food poisoning caused by foodborne pathogen contamination is not decreasing. To prevent the contamination of produce, a quick and easy, low-cost, environmentally-safe disinfection method that does not affect produce freshness or quality is needed. This study demonstrates a new-concept, circulating-water disinfection system that purifies water by using newly developed 'LED-PS (photosensitizer)-induced ROS generation unit'. Using various types of LED-PS induced ROS generation units, we investigated the conditions for reducing the density of various pathogenic bacteria by more than 3 log CFU / mL in 1 hour. The major operational factors affecting the density reduction of the LED-PS-induced ROS generation unit were analyzed. Depending on bacteria species, the density reduction rate was varied. The effect of the units on reducing the density of Bacillus cereus and Pectobacterium carotovorum subsp. carotovorum was high, but the effect on foodborne bacteria such as Escherichia coli was relatively low. In this circulating water disinfection system, the density reduction effect tended to increase as the flow rate increased and the initial bacterial density decreased. As the amount of PS absorbed beads increased, the density reduction effect increased exponentially in some bacteria. Model 3280, a double cylindrical unit connecting two single cylindrical units, could completely sterilize more than 3 log CFU/mL of B. cereus and P. carotovorum subsp. carotovorum in 30 minutes of LED irradiation.

• Environmental Mutagens and Carcinogens
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• v.22 no.4
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• pp.229-235
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• 2002

Thimerosal, a widely used preservative, has been well known to induce intracellular calcium mobilization in various cell types. However, the mechanism of its calcium mobilization is not clearly understood yet. For studying the mechanism of thimerosal-mediated calcium release, we have used HL60 cells in calcium-free Lockes solution that has no extracellular calcium. Thimerosal significantly reduced the lag period of initial calcium release whereas it enhanced the rate and magnitude of the calcium release in a dose-dependent manner. At the same time, we found that thimerosal generated superoxide anion by activating NADPH oxidase in dose- and time-dependent manner. Interestingly, the kinetics and the dosedependency of superoxide anion generation were very similar to those of intracellular calcium mobilization. In inhibitors study, the thimerosal-induced superoxide anion generation was significantly suppressed by DMSO as well as superoxide dismutase but not by genistein or EGTA. Surprisingly, the pretreatment with N-Acetyl-$_{L}$-Cysteine blocked almost completely the thimerosal-induced calcium increase, indicating that ROS playa key role in the calcium mobilization. The present results suggest that thimerosal-induced calcium mobilization is possibly mediated by the activation of NADPH oxidase and subsequent ROS generation.n.