• Biomedical Science Letters
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• v.11 no.2
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• pp.103-108
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• 2005

2-Deoxyribonolactone (dL) arises as a major DNA damage induced by a variety of agents, involving free radical attack and oxidation of C1'-deoxyribose in DNA. We investigated whether dL lesions can be repaired in mammalian cells and the mechanisms underlying the role of DNA polymerase $\beta$ in processing of dL lesions. Pol $\beta$ appeared to be trapped by dL residues, resulting in stable DNA-protein cross-links. However, repair DNA synthesis at site-specific dL sites occurred effectively in cell-free extracts, but predominantly accompanied by long-patch base excision repair (BER) pathway. Reconstitution of long-patch BER demonstrated that FEN1 was capable of removing the displaced flap DNA containing a 5'-dL residue. Cellular repair of dL lesions was largely dependent on the DNA polymerase activity of Pol $\beta$. Our observations reveal repair mechanisms of dL and define how mammalian cells prevent cytotoxic effects of oxidative DNA lesions that may threaten the genetic integrity of DNA.

• Korean Journal of Pharmacognosy
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• v.38 no.4
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• pp.372-375
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• 2007

Reactive oxygen species(ROS) or free radicals are produced in the pathogenesis of human diseases including atherosclerosis, diabetes, cancer, and aging. Antioxidants are associated with the prevention of ROS-induced tissue and cellular damage in the various diseases. This study investigated the antioxidative activities of the methanol extract of Alisma plantagoaquatica var. orientale and its main component under conditions of radical generation using allophycocyanin and ferric-thiocyanate assay. Alisol B 23-acetate as a main component was isolated from the methanol extract of Alisma plantago-aquatica var. orientale. In results, the extract of Alisma plantago-aquatica var. orientale showed inhibitory activity on AAPH [2,2'-azobis(2-amidinopropane)dihydrochloride]-induced protein oxidation. Also, the extract of Alisma plantago-aquatica var. orientale and alisol B 23-acetate inhibited lipid peroxidation. These results indicate that Alisma plantago-aquatica var. orientale and alisol B 23-acetate show promise as therapeutic agents for various damages involving free radical reactions.

• Journal of Acupuncture Research
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• v.15 no.2
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• pp.135-145
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• 1998

Bupleury radix has been used for the treatment of fever, liver disease, inflammation in traditional medicine. The present study was carried out to evaluate the antioxidant effects of Bupleury radix aqua-acupuncture solution (BRAS) in vitro. Oxygen derived free radicals produced in the course of normal aerobic life, such as superoxide anion radical($O_2^-$ ), hydroxyl radicaI( OH), hydrogen peroxide($H_2O_2$) and singlet oxygen($^1O_2$) can attack polyunsaturated fatty acid in cell membranes, enzymes, other cell compounds, and give rise to lipid peroxidation, DNA damage, lipofuscin accumulation, structure alteration of cell membrane and cell death. In this study, antioxidant effects of BRAS on lipid peroxidation were determined according to the method of TBA. BRAS inhibited markedly peroxidation of linoleic acid during the autoxidation, and also inhibited lipid peroxidation induced by hydroxyl radical derived from $H_2O_2-Fe^{2+}$ in rat liver homogenate. And BRAS showed 30% scavenging effect on DPPH radical, also exhibited a 30% inhibitory effect on superoxide generation from xanthine-xanthine oxidase system. In addition, BRAS protected the cell death induced by tert-butyl hydroperoxide(t-BHP) and significantly increased cell viability in the normal rat liver cell(Ac2F).

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.115-115
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• 2001

Regular green tea consumption has been associated with a reduced risk of cancer, partly via antioxidant effects of green tea in protecting cellular components against free radical. In the present study, we evaluated the effect of green tea extract (GTE) on oxidative damage to DNA in CHL cells.(omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.282.1-282.1
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• 2002

Paeoniae radix is commonly used for various woman's health problems in traditional korean medicine. In order to develop new antioxidant for woman use. the ethanolic extracts of paeoniae radix (PRE) were prepared and various biological activities were evaluated. PRE showed potent free radical scavenging activity and moderate antioxidative activity in vitro. and also showed the protective effect on H2O2-induced DNA damage in mammalian cell. (omitted)

• Herbal Formula Science
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• v.8 no.1
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• pp.241-255
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• 2000

Sihosamultang(SST) has been used for the treatment of puerperal fever, liver disease in traditional medicine. The present study was carried out to evaluate the antioxidant effects of SST extract in vitro. The inhibitory effect of SST extract on lipid peroxidant was examined in the linoleic acid autoxidation system. In this test, SST extract significantly inhibited the time course of the lipid peroxidation. And SST extract showed about 73% scavenging effect on DPPH radical. And this extract inhibited not only the lipid peroxide formation induced by hydroxyl radical derived from $ H_{2}O_{2}-Fe^{2+}$ in the rat liver homogenate, but also the superoxide generation from xanthine-xanthine oxidase system in a dose-dependent manner. In addition, SST extract protected the hepatic cell death induced by tert-butyl hydroperoxide. These data indicated that SST might play a protective role against oxidative injury by free radicals.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2873-2876
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• 2010

Excess free iron generates oxidative stress that may contribute to the pathogenesis of various causes of neurodegenerative diseases. Previous studies have shown that one of the primary causes of increased brain iron may be the release of excess iron from intracellular iron storage molecules. In this study, we attempted to characterize the oxidative damage of DNA induced by the reaction of ferritin with $H_2O_2$. When DNA was incubated with ferritin and $H_2O_2$, DNA strand breakage increased in a time-dependent manner. Hydroxyl radical scavengers strongly inhibited the ferritin/$H_2O_2$ system-induced DNA cleavage. We investigated the generation of hydroxyl radical in the reaction of ferritin with $H_2O_2$ using a chromogen, 2,2'-azinobis-(2-ethylbenzthiazoline-6-sulfonate) (ABTS), which reacted with ${\cdot}OH$ to form $ABTS^{+\cdot}$. The initial rate of $ABTS^{+\cdot}$ formation increased as a function of incubation time. These results suggest that DNA strand breakage is mediated in the reaction of ferritin with $H_2O_2$ via the generation of hydroxyl radicals. The iron-specific chelator, deferoxamine, also inhibited DNA cleavage. Spectrophotometric study using a color reagent showed that the release of iron from $H_2O_2$-treated ferritin increased in a time-dependent manner. Ferritin enhanced mutation of the lacZ' gene in the presence of $H_2O_2$ when measured as a loss of $\alpha$-complementation. These results indicate that ferritin/$H_2O_2$ system-mediated DNA cleavage and mutation may be attributable to hydroxyl radical generation via a Fenton-like reaction of free iron ions released from oxidatively damaged ferritin.

• Korean Journal of Medicinal Crop Science
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• v.14 no.6
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• pp.322-328
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• 2006

Green tea is of particular source as it has been found to have strong antioxidant activities. The extracts of green tea during the commercial harvest seasons from April, 2003 to August, 2003 were compared. The purpose of this study was to determine the correlation between the polyphenol content of green teas and its antioxidant activities. The con-tent of total polyphenols was analyzed and several antioxidant testings were performed. The levels of total polyphenols were higher in the green teas (e.g. Woojeon, Sejak) harvested during very early spring and lower in the green teas harvested late(eg. Ipha, Yepcha). In particular, the free radical scavenging, the inhibition of LDL oxidation, the cytoprotective effect and the inhibition of DNA damage were correlated with the total polyphenol contents of green tea extracts harvested early spring such as Woojeon, Sejak and Jungjak. The results obtained here show that all extracts of green teas including purified green tea catechin, GTC, have strong antioxidant activities on oxidative stress in vifrθ. The variation in polyphenol content and antioxidant activities among various types of green tea by the harvesting time may provide critical information for investigators and consumers using tea in purposes of nutrition and chemoprevention.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.333-340
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• 1996

The relationship between ozone-induced damages and ethylend evolution was examined in tomato plants fumigated with ozone of 0.2 $\mu\ell/\ell$. The rate of evolution of ethylent by tomato plants was enhanced by ozone fumigation. Pretreatment of leaves with aminoethoxyvinylglycine (AVG), an inhibitor of ethylene evolution, significantly inhibited the evolution of ethylene that was induced by ozone and concomitantly reduced the extent of ozone-induced visible damage to leaves. Treatment with 2,5-norbonadiene (NBD), and inhibitor of the action of ethylene, strongly reduced the extent of visible damage caused by ozone, even though it did not suppress the evolution of ethylene. These results indicated that ethylene might play an important role in ozone-induced plant injuries at relatively short terms of ozone fumigation. Next, we examined the effect of tiron, a scanvenger of the free-radical, on evolution of ethylene and leaf injury caused by ozone. Tiron treatment strongly reduced the extent of ozone-induced injury, but had not inhibitory effect on the evolution of ethylene from tomato leaves. This result suggests the involvement of free-radical, such as superoxide radicals, in induction of injuries caused by ozone.

• Journal of Sasang Constitutional Medicine
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• v.13 no.1
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• pp.51-60
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• 2001

Effects of Taeumjowetang on Lipid Peroxidation by Free Radicals and Oxidative Damage of Hepatocytes by tert-Butyl Hydroperoxide. 1. Purpose The present study was carried out to evaluate the antioxidant effects of Taeumjowetang in vitro. 2. Methods In this study, antioxidant effects of TJT on lipid peroxidation were determined according to the method of TBA. (Abbreviation) TJT : Taeumjowetang, TBA : 2-thiobarbituric acid. 3. Results : 1) TJT inhibited markedly peroxidation of linoleic acid during the autoxidation. 2) TJT inhibited lipid peroxidation induced by hydroxyl radical derived from H2O2-Fe2+ in rat liver homogenate. 3) TJT showed 66% scavenging effect on DPPH radical. 4) TJT exhibited a 25% inhibitory effect on superoxide generation from xanthine-xan thine oxidase system. 5) To investigate the antioxidative effects of TJT on the hepatocytes, cultured normal rat liver cells(Ac2F) were prepared and incubated with or without TJT. After 16~18hr, cells placed in DMEM medium without serum, and then incubated with 1mM t-BHP for 2hr. Viable cells were detected by MTT assay. In this test, TJT protected the cell death induced by t-BHP and significantly increased cell viability in the normal rat liver cell. (Abbreviation) DPPH : ${\alpha},{\alpha}$-diphenyl-${\beta}$-picryl hydrazyl, DMEM : Dulbecco's Modified Eagle Medium, t-BHP : terr-butyl hydroperoxide, 4. Conclusion These results suggested that TJT might play a protective role in lipid peroxidation by free radicals.