• BMB Reports
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• v.35 no.1
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• pp.67-86
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• 2002

Three routes have been identified triggering neuronal death under physiological and pathological conditions. Excess activation of ionotropic glutamate receptors cause influx and accumulation of $Ca^{2+}$ and $Na^+$ that result in rapid swelling and subsequent neuronal death within a few hours. The second route is caused by oxidative stress due to accumulation of reactive oxygen and nitrogen species. Apoptosis or programmed cell death that often occurs during developmental process has been coined as additional route to pathological neuronal death in the mature nervous system. Evidence is being accumulated that excitotoxicity, oxidative stress, and apoptosis propagate through distinctive and mutually exclusive signal transduction pathway and contribute to neuronal loss following hypoxic-ischemic brain injury. Thus, the therapeutic intervention of hypoxic-ischemic neuronal injury should be aimed to prevent excitotoxicity, oxidative stress, and apoptosis in a concerted way.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.356-360
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• 2005

Xanthine dehydrogenase (XDH), a classic enzyme involved in purine catabolism, can catalyze the formation of redox-signaling reactive oxygen and nitrogen species such as superoxide and nitric oxide. We generated transgenic plants of Arabidopsis in which XDH was knocked out by introduction of hairpin RNA-expression vector. Expression analysis by reverse transcription-PCR and in-gel staining of XDH activity revealed that transgenic lines efficiently suppressedXDH expression at the transcriptional level, demonstrating that RNA interference was successfully induced. XDH-suppressed transgenic lines exhibitedincreased biomass production during the growth of seedlings.

• Molecular & Cellular Toxicology
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• v.5 no.3
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• pp.243-249
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• 2009

Melamine, which is used to produce melamine resin for various industrial applications, has a high nitrogen content by mass. For this reason, it has been illegally added to foods to increase their apparent protein content. In the present investigation, melamine-induced oxidative damage of human lymphocyte DNA was evaluated by Comet assay. The in vitro oxidative DNA damage caused by melamine increased in a dose-dependent manner. This DNA damage was significantly inhibited by treatment with ascorbate. Moreover, the traditional Korean medicinal herb, named Acanthopanax, red ginseng and green tea markedly reduced the DNA damage. Various edible plant extracts also inhibited melamine-induced oxidative DNA damage in vitro. Melamine enhanced intracellular ROS generation, and this effect was suppressed by treatment with various antioxidants.

• International Journal of Oral Biology
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• v.40 no.4
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• pp.217-221
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• 2015

Cariogenic Streptococcus mutans encounters a variety of host defense factors produced in oral cavity. Nitric oxide (NO) and NO-mediated reactive nitrogen species are potential antimicrobials of innate immunity that can threaten the fitness of S. mutans in their ecological niches. Streptococcal strategies to detoxify cytotoxic NO, which allow S. mutans to persist in caries or other environments of the oral cavity, remain unknown. In this study, we directly measured NO consumption rates of S. mutans isolated in Korea. Surprisingly, all S. mutans strains were unable to consume exogenous NO efficiently, while an intracellular parasite Salmonella enterica serovar Typhimurium expressing the NO-metabolizing enzyme flavohemoglobin consumed most of the NO. This result suggested that S. mutans has alternative detoxification systems for tolerating NO-induced nitrosative stresses.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.921-924
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• 2005

It is known that metallothionein (MT) plays a role in the scavenging of free radicals, which is produced under various stress conditions. MT may function as an antioxidant that protects against oxidative damage of DNA, protein, and lipid induced by superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide, and peroxynitrite. This study was undertaken to test the hypothesis that MT also protects from RNA damage induced by peroxynitrite, an important reactive nitrogen species that causes a diversity of pathological processes. A cell-free system was used. RNA damage was detected by the mobility of $tRNA^{Phe}$ in electrophoresis. Cleavages on tRNA were not induced by 3-morpholinosydnomine, which produces peroxynitrite directly. MT induced tRNA damage which was site specific.

• The Journal of Internal Korean Medicine
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• v.29 no.4
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• pp.988-999
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• 2008

Objectives : The study was conducted to evaluate antioxidative, anti-atherosclerotic and anti-hypertensive effects of natural remedies. Alisma Rhizome (AR) has been used for a long time in Asia in folk remedies for treatment of hypertension and stroke and has been used in Korean traditional medicine for the treatment of glycosuria, gonorrhea, hypercholesterolemia, hypertension, and jaundice and its diuretic effect. These pharmacological effects of AR might come from antioxidant properties of phytochemicals in these materials. Methods : In this study, the antioxidant activity of extract from AR was studied with in vitro methods by measuring the antioxidant activity by TEAC, measuring the scavenging effects on reactive oxygen species (ROS) [superoxide anion, hydroxyl radical] and on reactive nitrogen species (RNS) [nitric oxide and peroxynitrite] as well as measuring the inhibitory effect on $Cu^{2+}$ induced human LDL oxidation and on ACE. Results : The AR extracts were found to have a potent scavenging activity, as well as an inhibitory effect on LDL oxidation and on ACE against all of the reactive species tested, with the water extract showing particularly strong antioxidant activities. Conculsions : The AR extracts have antioxidative, anti-atherosclerotic and anti-hypertensive effects in an in vitro system, which can be used for developing pharmaceutical drugs against oxidative stress and atherosclerosis.

• Journal of Life Science
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• v.26 no.11
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• pp.1282-1288
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• 2016

Artemisia, a plant widely used as traditional herbal medicine in many countries, has drawn attention of the researchers. And its extracts or compounds are known to have an efficacy of antioxidant, anti-diabete, anti-cancer, anti-inflammation and neuroprotection. Sumaeyaksuk is a variant of the Artemisia argyi and major constituents are eupatilin and jaceosidin. This study was performed to investigate the effects of the sumaeyaksuk aqueous extract on inflammatory response induced by lipopolysaccharide (LPS) in human hepatoma HepG2 cells. To examine the potential hepatoprotective properties of sumaeyaksuk extract, cell viability, as well as nitric oxide (NO), reactive oxygen species (ROS), macrophage colony-stimulating factor (M-CSF), interleukin-8 (IL-8) levels, alanine transaminase (ALT), and aspartate transaminase (AST) activities, were measured. Cytotoxic activity of extracts on HepG2 cells was measured by MTT assay. Sumaeyaksuk extract did not induce cytotoxicity at concentrations of $0{\sim}400{\mu}g/mL$. NO and ROS levels significantly decreased with increasing concentration of the extract. The secretion levels of M-CSF and IL-8 were suppressed by sumaeyaksuk extract in a dose-dependent manner. Moreover, ALT (75.4%) and AST (61.6%) levels significantly decreased in sumaeyaksuk extract-treated cells at $400{\mu}g/mL$. These results suggested that the sumaeyaksuk extract attenuates the LPS-induced hepatotoxicity resulting from regulation of inflammatory factors and could potentially be used as a hepatitis therapeutic agent.

• Molecules and Cells
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• v.38 no.11
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• pp.982-990
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• 2015

Exposure of the skin to ultraviolet radiation can cause skin damage with various pathological changes including inflammation. In the present study, we identified the skin-protective activity of 1,2,3,4,6-penta-O-galloyl-${\beta}$-D-glucose (pentagalloyl glucose, PGG) in ultraviolet B (UVB) radiation-induced human dermal fibroblasts and mouse skin. PGG exhibited antioxidant activity with regard to intracellular reactive oxygen species (ROS) generation as well as ROS and reactive nitrogen species (RNS) scavenging. Furthermore, PGG exhibited anti-inflammatory activity, inhibiting the activation of nuclear factor-kappaB (NF-${\kappa}B$) and mitogen-activated protein kinase (MAPK) signaling, resulting in inhibition of the expression of pro-inflammatory mediators. Topical application of PGG followed by chronic exposure to UVB radiation in the dorsal skin of hairless mice resulted in a significant decrease in the progression of inflammatory skin damages, leading to inhibited activation of NF-${\kappa}B$ signaling and expression of pro-inflammatory mediators. The present study demonstrated that PGG protected from skin damage induced by UVB radiation, and thus, may be a potential candidate for the prevention of environmental stimuli-induced inflammatory skin damage.

• Journal of Life Science
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• v.24 no.5
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• pp.549-557
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• 2014

This study examined the quality characteristics of fermented black garlic (BG) with probiotics. Nine strains of probiotics were tested in media containing 20% BG. Four of the strains grew well in the BG media: Lactobacillus rhamnosus, L. paracasei subsp. paracasei, L. casei, and L. plantarum. These four strains were used to make 10, 20, and 30% BG fermented product, respectively. The number of viable cells, pH, acidity, S-allyl cysteine (SAC) concentration, and nitric oxide (NO) and reactive nitrogen species (ROS) generation in Raw 264.7 macrophage cells were measured. L. plantarum showed the best growth of all the strains in the BG media. The pH of all the samples decreased during fermentation, and the acidity increased acidity. However, they did not differ significantly from the pH and acidity of the control. In all four strains, the SAC content did not differ before and after fermentation. However, the SAC content increased, depending on the BG concentration. NO production was inhibited in the L. rhamnosus inoculation strain compared to the other strains. ROS generation was also significantly inhibited in the L. plantarum inoculation strain compared to the other strains. The results show that the characteristics of BG fermentation products are determined by the fermentation strain. Therefore, fermentation products with particular characteristics can be produced using a single strain or mixed strains.

• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.283-291
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• 2014

To study the distribution characteristics of diatom communities in relation to the gradient of water quality and land-use, water samples and epilithic diatoms were collected from 90 sites including mainstream and tributaries, in the Geum River System (GRS) during no rainfall, May 2011. Of 239 taxa identified, Achnanthes convergens and Cymbella minuta were dominated over all the sites. Cluster analysis on the GRS divided into three groups. Group 1 (G1) is the mountainous upstream, a relatively good water quality, and mainly consisted of saproxenous species. Group 2 (G2) is the urban sites, polluted (high in electric conductivity, total phosphate and soluble reactive phosphorus), and saproxenous and common species. Group 3 (G3) is the agriculture sites, and polluted (turbidity, total nitrogen, nitrate), and saprophilous species. There were some discrepancies between abiotic and biotic variables in GRS; biologically similar between G1 and G2, but abiotically similar between G2 and G3. These differences may attribute to not only physiological characteristics of diatom cells, but complicate relationships between microhabitat and water quality. Thus, an urgent development of generalized or standardized methods to diminish the differences between epilithic diatom community and environments is advent.