• Korean Journal of Medicinal Crop Science
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• v.25 no.5
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• pp.315-321
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• 2017

Background: Glycyrrhiza uralensis Radix (GR) is a crude drugs used in Asian countries that has been reported to prevent the progression of neurodegenerative diseases such as Alzheimer's disease. The present study examined whether GR and its active compounds, glycyrrhizic acid (GA) and isoliquiritigenin (IL), exerted protective effects on $H_2O_2$-induced oxidative damage in C6 glial cells. Methods and Results: We exposed C6 glial cells to hydrogen peroxide ($H_2O_2$) for 24 h and investigated the cellular response to GR and its active compounds by evaluating cell viability, reactivie oxygen species (ROS) production, and apoptosis-related protein expression. GR successfully mitigated the reduced cell viability and ROS production induced by $H_2O_2$ in C6 glial cells, IL and GA significantly increased the cell viability and decreased ROS production. In addition, IL and GA down-regulated apoptotic Baxdependent caspase-3 activation, but each compound exerted different mechanisms, i.e., IL dose-dependently decreased ROS production and, GA up-regulated anti-apoptotic Bcl-2 expression. Conclusions: These results demonstrated that GR and its active components, IL and GA, exhibit potential for use as natural neurodegenerative agents for the modulation of apoptosis in C6 glial cells.

• The Journal of Korean Medicine
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• v.21 no.4
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• pp.84-92
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• 2000

Objectives : The water extract of Sebsaeng-eum(SheShengYin) has been used for treatment of ischemic brain damage in oriental medicine, However, little is known about the mechanism by which the water extract of Sebsaeng-eum(SheShengYin) rescues brain cells from ischemic damages. Methods : To elucidate the protective mechanism on ischemic induced cytotoxicity, We investigated the regulation of LPS and PMA induced iNOS expression in $C_{6}$ glial cells. Results : LPS and PMA treatment for 48 h in $C_{6}$ glial cells markedly induced NO, but treatment of the cells with the water extract of Sebsaeng-eum(SheShengYin) decreased nitrite formation. In addition, LPS and PMA treatment for 48 h induced severe cell death in $C_{6}$ glial cells. However treatment of the cells with the water extract of Sebsaeng-eum(SheSheng Yin) did not induce significant changes compared to the control. LPS and PMA induced iNOS activation in $C_{6}$ glial cells caused chromosomal condensation and fragmentation of nuclei. Conclusions : Taken together, We suggest that the protective effects of the water extract of Sebsaeng-eum(SheShengYin) against ischemic brain damages may be mediated by regulation of iNOS during ischemic condition.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.6
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• pp.1423-1430
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• 2008

The water extract of Sopung-tang(SPT) has been traditionally used for treatment of psycologic disease and brain damage in oriental medicine. However, little is known about the mechanism by which the water extract of SPT rescues cells from these disease. Therefore, this study was designed to investigate the effect of SPT on the glutamate-induced toxicity of rat C6 glial cells. SPT have protective effects in glutamate-induced toxicity, which was revealed as apoptosis characterized by chromatic condensation and fragmentation and the loss of mitochondrial membrane potential in C6 glial cells. Also, SPT have inhibited the active form of caspase-3 and PARP and significantly protected the apoptotic phenomena by glutamate toxicity in C6 glial cells. However, SPT significantly recovered the depletion of GSH and inhibited the generation of ROS by glutamate in C6 glial cells. In addition, both SPT and antioxidants such as GSH and NAC protected the glutamate-induced cytotoxicity in C6 glial cells, indicating that SPT possibly have antioxidative effect. Specially, SPT were showed transcriptional factor significantly increased the activation of NF-${\kappa}B$ using the analysis of NF-${\kappa}B$ luciferase reporter system in C6 glial cells. These NF-${\kappa}B$ activation protected cells from glutamate-induced toxicity to generate the heme oxygenase-1(HO-1). Taken together, we suggest that SPT have protective effects in glutamate-induced toxicity via a antioxidative mechanism.

• Journal of Life Science
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• v.23 no.10
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• pp.1183-1191
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• 2013

Human apurinic/apyrimidinic endonuclease (APEX-1) is a multifunctional protein that is capable of repairing abasic sites and single-strand breaks in damaged DNA. In addition, it serves as a redox-modifying factor for a number of transcription factors. Identifying the transcriptional targets of APEX-1 is essential for understanding how it affects various cellular outcomes. Expression array analysis was used to identify glial cell-derived neurotropic factor receptor ${\alpha}1$ ($GFR{\alpha}1$), which is an encoding receptor for the glial cell-derived neurotropic factor (GDNF) family, the expression of which is induced by APEX-1. A target of GDNF/$GFR{\alpha}$ signaling, c-Src (Tyr418) was strongly phosphorylated by GNDF in the APEX-1 expressing cells. Moreover, GDNF initiated cell proliferation, measured by counting the number of cells, in the APEX-1 expressing cells. Importantly, the down-regulation of APEX-1 by siRNA caused a marked reduction in the $GFR{\alpha}1$ expression level, and it reduced the ability of GDNF to phosphorylate c-Src (Tyr418) and stimulate cell proliferation. These results demonstrate an association between APEX-1 and GDNF/$GFR{\alpha}$ signaling and suggest a potential molecular mechanism for the involvement of APEX-1 in cell survival and proliferation.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.327-334
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• 2020

Oxidative stress is common cause of neurodegenerative diseases. The purpose of this study is to investigate the in vitro free radical scavenging activity and protective effect of three Glycyrrhiza species including Glycyrrhiza uralensis, G. glabra, and a new variety of Glycyrrihza (Shinwongam, SW) against hydrogen peroxide-induced oxidative stress in C6 glial cells. In vitro assays, radical scavenging activities of G. uralensis, G. glabra, and SW against 2,2-diphenyl-1-picrylhydrazyl, ·OH, and O2- increased as concentration-dependent manner. In addition, the SW was found to contain the highest polyphenol and flavonoid contents. The treatment of H2O2 to C6 glial cell induced oxidative stress, whereas G. uralensis, G. glabra, and SW significantly increased the cell viability as dose-dependent manner. In particular, SW exerted stronger protective effect on H2O2-induced cytotoxicity, than G. uralensis and G. glabra. Furthermore, reactive oxygen species (ROS) formation was significantly elevated by H2O2 in C6 glial cells. However, treatments of G. uralensis, G. glabra, and SW decreased ROS formation. In addition, SW decreased pro-inflammatory related protein expression levels such as inducible nitric oxide synthase and cyclooxygenase-2, compared to H2O2-treated control group. These results indicated that G. uralensis and G. glavra, especially SW, may be useful for preventing from oxidative stress-induced neuronal damage by regulating inflammatory reaction.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.5
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• pp.235-239
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• 2002

It has been reported that lovastatin induced cell death and suppressed proliferation in various cell lines. In this study, we examined whether the cytotoxic effects of lovastatin could be prevented by Bcl-2 or $Bcl-_{XL}$ in C6 glial cells. Overexpression of human Bcl-2 or $Bcl-_{XL}$ prevented lovastatin $(25{\mu}M)-induced$ changes such as DNA fragmentation, chromatin condensation, disruption of cell membrane, and cleavage of poly (ADP-ribose) polymerase. Lovastatin-induced inhibition of cell proliferation was unaffected by Bcl-2 or $Bcl-_{XL}$ overexpression. These results suggest that Bcl-2 and $Bcl-_{XL}$ can prevent lovastatin-induced apoptosis in C6 glial cells, though the inhibition of proliferation remains unaffected by these proteins.

• Korean Journal of Pharmacognosy
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• v.46 no.2
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• pp.109-115
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• 2015

This study was investigated the radical scavenging effect and the protective activity of caffeic acid (CA) against oxidative stress. CA showed strong 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and hydroxyl radical ( OH) scavenging activity, showing 42.00% and 87.22% at 5 μM concentration of DPPH and ·OH scavenging activity, respectively. Furthermore, we studied protective activity of CA from amyloid beta (A${\beta}$_25-35) and lipopolysaccharide (LPS) induced neuronal cell damage and neuronal inflammation using C6 glial cells. The treatment of A${\beta}$_25-35 to C6 glial cell showed declines in cell viability and high generation levels of reactive oxygen species (ROS). However, the treatment of CA increased cell viability. The treatment of 5 ${{\mu}M}$ CA led to the elevation of cell viability from 59.28% to 81.22%. In addition, the production of ROS decreased cellular levels of ROS by the treatment of CA. The treatment of LPS to C6 glial cells increased significant elevation of nitric oxide (NO) production, while CA decreased NO production significantly. The production of NO increased by the treatment of LPS to 131.08%, while CA at the concentration of 1 ${{\mu}M}$ declined the NO production to 104.86%. The present study indicated thatCA attenuated A${\beta}$_25-35-induced neuronal oxidative stress and inflammation by LPS, suggesting as a promising agent for the neurodegenerative diseases.

• 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.

• The Journal of Internal Korean Medicine
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• v.34 no.2
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• pp.178-191
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• 2013

Objectives : In this study, we made an effort to investigate the protective mechanism of Ukgan-san (UGS) extracts on hypoxia-induced C6 glial cell death. Methods : The cell viability was assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MMT) assay and cell morphological changes were analysed with microscope after staining with crystal violet (CV). Reactive oxygen species (ROS) formation was assessed by flow cytometer after staining with 2'7'-dichlorofluorescein diacetate (DCF-DA). We also analyzed expression of hypoxia-inducible factor-1 alpha (HIF-$1{\alpha}$) and p53, processing of procaspase-3 and procyclic acidic repetitive protein (PARP) by western blot method. Results : We estimated the elevated cell viability by UGS extract on $CoCl_2$-induced C6 glial cells. UGS attenuated $CoCl_2$-induced ROS formation in C6 glial cells and also showed a protective activity compared to antioxidants and exhibited abrogation of LDH-released by $CoCl_2$. UGS suppressed the typical apoptotic cell death markers, caspase-3 and PARP activation. UGS inhibited $CoCl_2$-induced HIF-1${\alpha}$ expression which is known as a major regulator for hypoxia-induced cell death, and suppressed p53 expression. Conclusions : These results suggest that UGS extract contains protective constituents for hypoxia-induced C6 glial cell death.

• Nutrition Research and Practice
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• v.13 no.4
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• pp.279-285
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• 2019

BACKGROUND/OBJECTIVES: Excessive production of reactive oxygen species (ROS) such as hydroxyl (${\cdot}OH$), nitric oxide (NO), and hydrogen peroxide ($H_2O_2$) is reported to induce oxidative stress. ROS generated by oxidative stress can potentially damage glial cells in the nervous system. Cordyceps militaris (CM), a kind of natural herb widely found in East Asia. In this study, we investigated the free radical scavenging activity of the CM extract and its neuroprotective effects in $H_2O_2$-induced C6 glial cells. MATERIALS/METHODS: The ethanol extract of CM ($100-1,000{\mu}g/mL$) was used to measure DPPH, ${\cdot}OH$, and NO radical scavenging activities. In addition, hydrogen peroxide ($H_2O_2$)-induced C6 glial cells were treated with CM at $0.5-2.5{\mu}g/mL$ for measurement of cell viability, ROS production, and protein expression resulting from oxidative stress. RESULTS: The CM extract showed high scavenging activities against DPPH, ${\cdot}OH$, and NO radicals at concentration of $1,000{\mu}g/mL$. Treatment of CM with $H_2O_2$-induced oxidative stress in C6 glial cells significantly increased cell viability, and decreased ROS production. Cyclooxygenase-2 and inducible nitric oxide synthase protein expression was down-regulated in CM-treated groups. In addition, the protein expression level of phospho-p38 mitogen-activated protein kinase (p-p38 MAPK), phospho-c-Jun N-terminal kinase (p-JNK), and phospho-extracellular regulated protein kinases (p-ERK) in $H_2O_2$-induced C6 glial cells was down-regulated upon CM administration. CONCLUSION: CM exhibited radical scavenging activity and protective effect against $H_2O_2$ as indicated by the increased cell viability, decreased ROS production, down-regulation of inflammation-related proteins as well as p-p38, p-JNK, and p-ERK protein levels. Therefore, we suggest that CM could play the protective role from oxidative stress in glial cells.