• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.93-93
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• 2002

Oxidative stress has been associated with a number of diseases in humans. Among the sources that can generate oxidative stress, it has been reported that iron can generate reactive oxygen species (ROS) with thiol. In iron overload state, increased thiol levels in plasma appeared to be associated with human mortality.(omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.211.1-211.1
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• 2003

There are now increasing evidences that free radicals and reactive oxygen species are involved in a variety of pathological events. Flavonoids. a group of polypenolic compounds, are widespread in the human food supply. This study was carried out to investigate the antioxidant activity of these compounds. myriceitn and (+)-catechin on B 16Fl0. murine melanoma cell line in oxidative stress. Oxidative stress was induced by exposure to hydrogen peroxide. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.290.1-290.1
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• 2002

The surgically ovariectomized rat induces aging by reactive oxyyen species(ROS) generation. Free oxygen radicals have been proposed as important causative agents of aging. The purpose of this study was to investigate the effect of Chondroitin Sulfate(CS) to prevent ovariectomy(OVX) induced oxidative stress and atherosclerosis. The OVX rats were given intraperitoneally CS at dose of 100mg/kg and 200mg/kg daily for fifteen weeks. (omitted)

• Journal of Nutrition and Health
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• v.29 no.7
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• pp.721-728
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• 1996

The level of oxidative tissue damage caused by free radicals generated from ethanol oxidation was determined in the myocardium of chronic ethanol fed-rats and the protective action of various radical scavenging enzymes was monitored, also. Adult male Sprague-Dawley rats were given ethanol in an amount of 36% of total calories via Lieber-DeCarli liquid diet for 6 weeks. Control group was pair-fed with the diet containing isocaloric amount of dextrin-maltose instead of ethanol. Chronic ethanol administration resulted in the increased amount of myocardial thiobarbituric acid reactive substance(TBARS), th parameter of lipid peroxidation, under our experimental condition. Chronic ethanol ingestion did not cause any change in activities of either glutathione peroxidase or glutathione reductase and glucose-6-phosphate dehydrogenase were decreased after ethanol treatment. Therefore, chronic ethanol administration seemed to cause considerble changes in cellular defense function against oxidative tissue damage in rat myocardium through glutathione utilizing system and radical generation system. However the ultimate net result of chronic ethanol inestion on the myocardium of rat was the oxidative tissue damage revealed by increased TBARS content.

• Applied Science and Convergence Technology
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• v.23 no.4
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• pp.169-178
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• 2014

Fluid model based numerical analysis is done to simulate a low damage etch back system for 20 nm scale semiconductor fabrication. Etch back should be done conformally with very high material selectivity. One possible mechanism is three steps: reactive radical generation, adsorption and thermal desorption. In this study, plasma generation and transport steps are analyzed by a commercial plasma modeling software package, CFD-ACE+. Ar + $CF_4$ ICP was used as a model and the effect of reactive gas inlet position was investigated in 2D and 3D. At 200~300 mTorr of gas pressure, separated gas inlet scheme is analyzed to work well and generated higher density of F and $F_2$ radicals in the lower chamber region while suppressing ions reach to the wafer by a double layer conducting barrier.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.57-62
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• 1998

We hypothesized the primary effect of ginseng was to protect cell membrane fatty acids from decomposition caused by free radicals. To confirm the antioxidant effect of ginseng, we measured the inhibitory effect on the formation of thiobarbituric acid-reactive substances, an indicator of lipid peroxidation, and evaluated the free radical scavenging effect of ginseng by electron spin resonance spectrometer, and gas chromatography. The results showed that thiobarbituric acid-reactive substances formed and the loss of arachidonic acid during lipid peroxidation, and that hydroxyl (-like) radical peak formed by the iron complex (ferric nitrilotriacetate, an known free radical generator in vitro) were completely inhibited by ginseng extract. This antioxidant effect of ginseng may be responsible for its wide pharmacological actions in clinical practice. As the free radical reactions in general are rapid and non-specific, ginseng seems to act as a normalizer, rather than a general tonic, at the stages of acute or chronic active phase of the various diseases.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1547-1552
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• 2022

β-Amyrin is a pentacyclic triterpene widely distributed in leaves and stems worldwide. The ability of β-amyrin to induce the production of reactive oxygen species (ROS) in microorganisms suggests its potential as an antimicrobial agent. Thus, this study aimed to elucidate the antibacterial mode of action of β-amyrin. We treated Escherichia coli cells with β-amyrin and found that it triggered ROS accumulation. Excessive stress caused by ROS, particularly hydroxyl radicals, induces glutathione (GSH) dysfunction. GSH protects cells from oxidative and osmotic stresses; thus, its dysfunction leads to membrane depolarization. The resultant change in membrane potential leads to the release of apoptotic proteins, such as caspases. The activated caspases-like protein promotes the cleavage of DNA into single strands, which is a hallmark of apoptosis-like death in bacteria. Apoptotic cells usually undergo events such as DNA fragmentation and phosphatidylserine exposure, differentiating them from necrotic cells, and the cells treated with β-amyrin in this study were positive for annexin V and negative for propidium iodide, indicating apoptosis-like death. In conclusion, our findings suggest that the antibacterial mode of action of β-amyrin involves the induction of ROS, which resulted in apoptosis-like death in E. coli.

• Toxicological Research
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• v.16 no.1
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• pp.1-8
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• 2000

Astrocytes generate free radicals including nitric oxide (NO) and reactive oxygen intermediates(ROI) which in turn play roles in the pathogenesis of degenerative diseases and sclerotic changes of the brain. This study was designed to evaluate the mechanism that free radicals contribute to the cytotoxicty of rat neonatal primary astrocytes. Treatment with NO donors alone including soldium nitroprusside(SNP), S-nitrosoglucathinoe (GSNO), and S-nitroso-n-acetylpenicillamine (SNAP) showed a little effect on the death of rat neonatal primary astrocytes, whereas SNP markedly induced the death of RAW 264.7 cells. ROI inculding H2O2 and O2 donor also slightly induced the death of rat primary astrocytes. However, 3-morpholinosydnonimine(SIN-1), a donor of peroxynitrite (ONOO), which is a reactive compound of NO with superoxide, significantly decreased the viability of rat primary astrocytes in a dose-dependent manner. Cells were retarded in outgrowth of viability of cellular processes with cell shrinkage and detachment from culture dishes. Hoechst staining demonstrated that SIN-1-induced cell death might be due to an apoptosis which was characterized by nuclear condensation and fragmentation. SIN-1-induced apoptosis was prevented by the pretreatment with superoxide dismutase (SOD) and catalase in rat primary astorocytes. Furthermore, prevention of the generation of reduced glutathione (GSH) by DL-buthionine-[S, R]-sulfoximine (BSO) aggravated the cytotoxic effects of SNP, benzene triol, and SIN-1 in rat primary astrocytes. Taken together, it is suggested that peroxynitrite may be a major effector of apoptosis and cellular antioxidant system is important for cell survival in rat prima교 astrocytes.

• Archives of Pharmacal Research
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• v.27 no.3
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• pp.340-345
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• 2004

Our work in this study was made in the microsomal fraction to evaluate the lipid peroxidation by measuring superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) and to elucidate the preventive role of CS in the $CCl_4$-induced oxidative stress. The excessive lipid peroxidation by free radicals derived from $CCl_4$ leads to the condition of oxidative stress which results in the accumulation of MDA. MDA is one of the end-products in the lipid peroxidation process and oxidative stress. MDA, lipid peroxide, produced in this oxidative stress causes various diseases related to aging and hepatotoxicity, etc. Normal cells have a number of enzymatic and nonenzymatic endogenous defense systems to protect themselves from reactive species. The enzymes in the defense systems, for example, are SOD, CAT, and GPx. They quickly eliminate reactive oxygen species (ROS) such as superoxide anion free radicalㆍO$^{[-10]}$ $_2$, hydrogen peroxide $H_2O$$_2$ and hydroxyl free radicalㆍOH. CS inhibited the accumulation of MDA and the deactivation of SOD, CAT and GPx in the dose-dependent and preventive manner. Our study suggests that CS might be a potential scavenger of free radicals in the oxidative stress originated from the lipid peroxidation of the liver cells of $CCl_4$-treated rats.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.809-815
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• 2003

Since reactive oxygen species (ROS) and hydroxyl radicals ($^-OH$) play an important role in the pathogenesis of many human degenerative diseases, much attention has focused on the development of safe and effective antioxidants. Preliminary experiments have revealed that the methanol (MeOH) extract of the stem of Prunus davidiana exerts inhibitory/scavenging activities on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals, total ROS and peroxynitrites ($ONOO^-$). In the present study, the antioxidant activities of this MeOH extract and the organic solvent-soluble fractions, dichloromethane (CH$_2$Cl$_2$), ethyl acetate (EtOAc), and n-butanol (n-BuOH), and the water layer of P. davidiana stem were evaluated for the potential to inhibit $^-OH$ and total ROS generation in kidney homogenates using 2',7'-dichlorodihydrofluorescein diacetate (DCHF-DA), and for the potential to scavenge authentic $ONOO^-$. We also evaluated the inhibitory activity of seven flavonoids isolated from P. davidiana stem, kaempferol, kaempferol 7-Ο-$\beta$-D-glucoside, (+)-catechin, dihydrokaempferol, hesperetin 5-Ο-$\beta$-D-glucoside, naringenin and its 7-Ο-$\beta$-D-glucoside, on the total ROS, $^-OH$ and $ONOO^-$ systems. For the further elucidation of the structure-inhibitory activity relationship of flavonoids on total ROS and 'OH generation, we measured the antioxidant activity of sixteen flavonoids available, including three active flavonoids isolated from P. davidiana, on the total ROS and 'OH systems. We found that the inhibitory activity on total ROS generation increases in strength with more numerous hydroxyl groups on their structures. Also, the presence of an ortho-hydroxyl group, whether on the Aring or S-ring, and a 3-hydroxyl group on the C-ring increased the inhibitory activity on both total ROS and $^-OH$ generation.