• International Journal of Oral Biology
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• v.45 no.4
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• pp.179-189
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• 2020

Green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) is a potent antioxidant with protective effects against neurotoxicity. However, it is currently unclear whether EGCG protects neuronal cells against radiation-induced damage. Therefore, the objective of this study was to investigate the effects of EGCG on ultraviolet (UV)-induced oxidative stress and apoptosis in PC12 cells. The effects of UV irradiation included apoptotic cell death, which was associated with DNA fragmentation, reactive oxygen species (ROS) production, enhanced caspase-3 and caspase-9 activity, and poly (ADP-ribose) polymerase cleavage. UV irradiation also increased the Bax/Bcl-2 ratio and mitochondrial pathway-associated cytochrome c expression. However, pretreatment with EGCG before UV exposure markedly decreased UV-induced DNA fragmentation and ROS production. Furthermore, the UV irradiation-induced increase in Bax/Bcl-2 ratio, cytochrome c upregulation, and caspase-3 and caspase-9 activation were each ameliorated by EGCG pretreatment. Additionally, EGCG suppressed UV-induced phosphorylation of p38 and rescued UV-downregulated phosphorylation of ERK. Taken together, these results suggest that EGCG prevents UV irradiation-induced apoptosis in PC12 cells by scavenging ROS and inhibiting the mitochondrial pathways known to play a crucial role in apoptosis. In addition, EGCG inhibits UV-induced apoptosis via JNK inactivation and ERK activation in PC12 cells. Thus, EGCG represents a potential neuroprotective agent that could be applied to prevent neuronal cell death induced by UV irradiation.

• Biomolecules & Therapeutics
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• v.32 no.1
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• pp.77-83
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• 2024

Alzheimer's disease (AD) is a neurodegenerative disease characterized by neuronal cell death and memory impairment. Corticosterone (CORT) is a glucocorticoid hormone produced by the hypothalamic-pituitary-adrenal axis in response to a stressful condition. Excessive stress and high CORT levels are known to cause neurotoxicity and aggravate various diseases, whereas mild stress and low CORT levels exert beneficial actions under pathophysiological conditions. However, the effects of mild stress on AD have not been clearly elucidated yet. In this study, the effects of low (3 and 30 nM) CORT concentration on Aβ_25-35-induced neurotoxicity in SH-SY5Y cells and underlying molecular mechanisms have been investigated. Cytotoxicity caused by Aβ_25-35 was significantly inhibited by the low concentration of CORT treatment in the cells. Furthermore, CORT pretreatment significantly reduced Aβ_25-35-mediated pro-apoptotic signals, such as increased Bim/Bcl-2 ratio and caspase-3 cleavage. Moreover, low concentration of CORT treatment inhibited the Aβ_25-35-induced cyclooxygenase-2 and pro-inflammatory cytokine expressions, including tumor necrosis factor-α and interleukin-1β. Aβ_25-35 resulted in intracellular accumulation of reactive oxygen species and lipid peroxidation, which were effectively reduced by the low CORT concentration. As a molecular mechanism, low CORT concentration activated the nuclear factor-erythroid 2-related factor 2, a redox-sensitive transcription factor mediating cellular defense and upregulating the expression of antioxidant enzymes, such as NAD(P)H:quinone oxidoreductase, glutamylcysteine synthetase, and manganese superoxide dismutase. These findings suggest that low CORT concentration exerts protective actions against Aβ_25-35-induced neurotoxicity and might be used to treat and/or prevent AD.

• Korean Journal of Clinical Pharmacy
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• v.13 no.1
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• pp.29-39
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• 2003

Neurodegenerative disorders are associated with apoptosis as a causing factor or an inducer. On the other hand, it has been reported that epigallocatechin gallate (EUG), one of antioxidants and flavonoids, and z-VAD-fmk, a nonselective caspase inhibitor, suppress oxidative-radical-stress-induced apoptosis. However, it is not yet known what is the effects of EGCG and z-VAD-fmk on the apoptotic pathway is through phosphoinositide 3-kinase (PI3K), Akt and glycogen synthase kinase-3 (GSK-3) as well as mitochondria, caspase-3 and poly (ADP-ribose) polymerase (PARP). We investigated the effects of EGCG by using $H_2O_2$ treated N18D3 cells, mouse DRG hybrid neurons. Methods: Following 30 min $100\;{\mu}m\;H_2O_2$ exposure, the viability of N18D3 cells (not pretreated vs. EGCG or z-VAD-fmk pretreated) was evaluated by using MTT assay. The effect of EGCG on immunoreactivity (IR) of cytochrome c, caspase-3, PARP, PI3K/Akt and GSK-3 was examined by using Western blot, and was compared with that of z-Y4D-fmk. Results: EGCG or z-VAD-fmk pretreated N18D3 cells showed increased viability. Dose-dependent inhibition of caspase-3 activation accompanied by PARP cleavage were demonstrated by pretreatment of both agents. However, inhibition of cytochrome c release was only detected in EGCG pretreated N18D3 cells. On the pathway through PI3K/Akt and GSK-3, however, the result of Western blot in EGCG pretreated N18D3 cells showed decreased IR of Akt and GSK-3 and increased IR of p85a PI3K, phosphorylated Akt and GSK-3, and contrasted with that in z-VAD-fmk pretreated N18D3 cells showing no changes on each molecule. Conclusion: These data show that EGCG affects apoptotic pathway through upstream signal including PI3K/Akt and GSK-3 pathway as well as downstream signal including cytochrome c and caspase-3 pathway. Therefore, these results suggest that EGCG mediated activation of PI3K/Akt and inhibition GSK-B could be new potential therapeutic strategy for neurodegenerative diseases associated with oxidative injury.

• Applied Biological Chemistry
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• v.51 no.2
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• pp.129-135
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• 2008

Berberine is an isoquinoline alkaloid used in traditional Chinese medicine and has been isolated from a variety of plants, such as Coptis chinensis and Phellodendron amurense. It has a wide spectrum of clinical applications such as in anti-tumor, anti-microbial, and anti-inflammatory activities. However, it is still unknown that berberine related with reactive oxygen species (ROS)-mediated apoptosis pathway in human hepatoma HepG2 cells. In the present study, we are examined the molecular mechanism of ROS- and p38 MAP kinase-mediated apoptosis by berberine in HepG2 cells. Berberine increased cytotoxicity effects by time- and does-dependent manner. $LD_{50}$ was detected 50 ${\mu}M$ at 48h of exposure to berberine. Nuclei cleavage and apoptotic DNA fragmentation were observed in cells treated with 50 ${\mu}M$ of berberine for 48h. Moreover, berberine induced the activating of caspase-3, p53, p38 and Bax expression, whereas the expression of anti-apoptotic signaling pathways, Bcl-2, was decreased. Additionally, berberine-treated cells had an increased level of generation of ROS and nitric oxide (NO). These results indicated that berberine induces apoptosis of HepG2 cells may be mediated oxidative injury acts as an early and upstream change, triggers mitochondrial dysfunction, Bcl-2 and Bax modulation, p38 and p53 activation, caspase-3 activation, and consequent leading to apoptosis.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.9
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• pp.1420-1430
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• 2018

Objective: Epigallocatechin-3-gallate (EGCG) is a major ingredient of catechin polyphenols and is considered one of the most promising bioactive compounds in green tea because of its strong antioxidant properties. However, the protective role of EGCG in bovine oocyte in vitro maturation (IVM) has not been investigated. Therefore, we aimed to study the effects of EGCG on IVM of bovine oocytes. Methods: Bovine oocytes were treated with different concentrations of EGCG (0, 25, 50, 100, and $200{\mu}M$), and the nuclear and cytoplasmic maturation, cumulus cell expansion, intracellular reactive oxygen species (ROS) levels, total antioxidant capacity, the early apoptosis and the developmental competence of in vitro fertilized embryos were measured. The mRNA abundances of antioxidant genes (nuclear factor erythriod-2 related factor 2 [NRF2], superoxide dismutase 1 [SOD1], catalase [CAT], and glutathione peroxidase 4 [GPX4]) in matured bovine oocytes were also quantified. Results: Nuclear maturation which is characterized by first polar body extrusion, and cytoplasmic maturation characterized by peripheral and cortical distribution of cortical granules and homogeneous mitochondrial distribution were significantly improved in the $50{\mu}M$ EGCG-treated group compared with the control group. Adding $50{\mu}M$ EGCG to the maturation medium significantly increased the cumulus cell expansion index and upregulated the mRNA levels of cumulus cell expansion-related genes (hyaluronan synthase 2, tumor necrosis factor alpha induced protein 6, pentraxin 3, and prostaglandin 2). Both the intracellular ROS level and the early apoptotic rate of matured oocytes were significantly decreased in the $50{\mu}M$ EGCG group, and the total antioxidant ability was markedly enhanced. Additionally, both the cleavage and blastocyst rates were significantly higher in the $50{\mu}M$ EGCG-treated oocytes after in vitro fertilization than in the control oocytes. The mRNA abundance of NRF2, SOD1, CAT, and GPX4 were significantly increased in the $50{\mu}M$ EGCG-treated oocytes. Conclusion: In conclusion, $50{\mu}M$ EGCG can improve the bovine oocyte maturation, and the protective role of EGCG may be correlated with its antioxidative property.

• Journal of Life Science
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• v.23 no.10
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• pp.1223-1229
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• 2013

Ursolic acid (UA) a bio-active ingredient found in a variety of fruits and vegetables, and it has potent antioxidant activity. However, the role of UA in mouse embryonic stem (ES) cells is poorly understood. This study investigated the functional role of UA in regulating the development of mouse ES cells under hypoxia. Hypoxia did not exert a significant effect on the undifferentiated state of mouse ES cells. However, it induced reactive oxygen species (ROS) generation and increased the level of lactate dehydrogenase (LDH) production at 48 h of hypoxic exposure. Conversely, oxidative stress induced by hypoxia was significantly inhibited by UA ($30{\mu}M$) pretreatment. Hypoxia significantly decreased cell survival and the level of [$^3H$] thymidine incorporation, both of which recovered following pretreatment of UA. In addition, UA decreased the apoptotic effect of hypoxia by attenuating caspase-3 cleavage or by recovering cellular inhibition of the apoptotic protein (cIAP)-2 and Bcl-2 expression. We further found that UA decreased senescence-associated beta-galactosidase activity. We suggest that UA is a natural antioxidant and one of the functional modulators of hypoxia-induced survival, apoptosis, proliferation, and aging in mouse ES cells.

• Journal of Life Science
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• v.29 no.2
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• pp.191-197
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• 2019

Parkinson's disease (PD) is a progressive neurodegenerative disease that mainly affects motor system with clinical features such as bradykinesia, rigidity, tremor and abnormal posture. PD is characterized by the death of dopaminergic neurons in the substantia nigra pars compacta, which is associated with accumulation of oxidative stress and dysregulation of intracellular signaling pathway. Quercetin-3-O-glucuronide (Q3GA), a major metabolite of quercetin, has been reported to have neuroprotective effects. In this study, we examined the neuroprotective effect of Q3GA against 1-methyl-4-phenyl pyridinium ($MPP^+$)-induced neurotoxicity of PD and the underlying molecular mechanisms in SH-SY5Y cells. MTT and LDH assay showed that Q3GA significantly decreased $MPP^+$-induced cell death, which is accompanied by a reduction in poly (ADP-ribose) polymerase (PARP) cleavage. Furthermore, it attenuated $MPP^+$-induced intracellular reactive oxygen species (ROS) with the reduction of Bax/ Bcl-2 ratio. Moreover, Q3GA significantly increased the phosphorylation of Akt and cAMP response element binding protein (CREB), but it has no effects on the phosphorylation of extracellular signal-regulated kinase (ERK). Taken together, these results demonstrate that Q3GA significantly attenuates $MPP^+$-induced neurotoxicity through ROS reduction and Akt/CREB signaling pathway in SH-SY5Y cells. Our findings suggest that Q3GA might be one of the potential candidates for the prevention and/or treatment of PD.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8
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• pp.1112-1121
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• 2019

Objective: Gram-negative bacteria lipopolysaccharide (LPS) has been reported to be associated with uterine impairment, embryonic resorption, ovarian dysfunction, and follicle retardation. Here, we aimed to investigate the toxic effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes. Methods: First, we developed an in vitro model to study the response of bovine cumulusoocyte complexes (COCs) to LPS stress. After incubating germinal vesicle COCs in $10{\mu}g/mL$ of LPS, we analyzed the following three aspects: the expression levels of the LPS receptor toll-like receptor 4 (TLR4) in COCs, activities of intracellular signaling protein p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-${\kappa}B$); and the concentrations of interleukin (IL)-$1{\beta}$, tumor necrosis factor (TNF)-${\alpha}$, and IL-6. Furthermore, we determined the effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes. Results: The results revealed that LPS treatment significantly elevated TLR4 mRNA and protein expression levels in COCs. Exposure of COCs to LPS also resulted in a marked increase in activity of the intracellular signaling protein p-p38 MAPK and NF-${\kappa}B$. Furthermore, oocytes cultured in maturation medium containing LPS had significantly higher concentrations of the proinflammatory cytokines IL-$1{\beta}$, TNF-${\alpha}$, and IL-6. LPS exposure significantly decreased the first polar body extrusion rate. The cytoplasmic maturation, characterized by polar body extrusion and distribution of peripheral cortical granules, was significantly impaired in LPS-treated oocytes. Moreover, LPS exposure significantly increased intracellular reactive oxygen species levels and the relative mRNA abundance of the antioxidants thioredoxin (Trx), Trx2, and peroxiredoxin 1 in oocytes. Moreover, the early apoptotic rate and the release of cytochrome C were significantly increased in response to LPS. The cleavage, morula, and blastocyst formation rates were significantly lower in parthenogenetically activated oocytes exposed to LPS, while the incidence of apoptotic nuclei in blastocysts was significantly increased. Conclusion: Together, these results provide an underlying mechanism by which LPS impairs maturation potential in bovine oocytes.

• Journal of Veterinary Science
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• v.24 no.2
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• pp.24.1-24.13
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• 2023

Background: Ergothioneine (EGT) is a natural amino acid derivative in various animal organs and is a bioactive compound recognized as a food and medicine. Objectives: This study examined the effects of EGT supplementation during the in vitro maturation (IVM) period on porcine oocyte maturation and subsequent embryonic development competence after in vitro fertilization (IVF). Methods: Each EGT concentration (0, 10, 50, and 100 μM) was supplemented in the maturation medium during IVM. After IVM, nuclear maturation, intracellular glutathione (GSH), and reactive oxygen species (ROS) levels of oocytes were investigated. In addition, the genes related to cumulus function and antioxidant pathways in oocytes or cumulus cells were investigated. Finally, this study examined whether EGT could affect embryonic development after IVF. Results: After IVM, the EGT supplementation group showed significantly higher intracellular GSH levels and significantly lower intracellular ROS levels than the control group. Moreover, the expression levels of hyaluronan synthase 2 and Connexin 43 were significantly higher in the 10 μM EGT group than in the control group. The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and NAD(P)H quinone dehydrogenase 1 (NQO1) were significantly higher in the oocytes of the 10 μM EGT group than in the control group. In the assessment of subsequent embryonic development after IVF, the 10 μM EGT treatment group improved the cleavage and blastocyst rate significantly than the control group. Conclusions: Supplementation of EGT improved oocyte maturation and embryonic development by reducing oxidative stress in IVM oocytes.

• Journal of Life Science
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• v.24 no.1
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• pp.26-38
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• 2014

To examine the antioxidant activities of 11n selected miscellaneous cereal grains (proso millet, yellow glutinous proso millet, hwanggeumchal sorghum, glutinous sorghum, white glutinous sorghum, yellow glutinous foxtail millet, nonglutinous foxtail millet, green glutinous foxtail millet, golden foxtail millet, barnyard millet, and adlay), the free radical-scavenging activities of 80% ethanol extracts of the individual grains were investigated using 1,1-diphenyl-2-picryl-hydrazl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods. The ethanol extracts of hwanggeumchal sorghum, glutinous sorghum, and barnyard millet grains exhibited more potent free radical-scavenging activities as compared to the other grains. When these three ethanol extracts were sequentially fractionated with n-hexane, methylene chloride, ethyl acetate, and n-butanol, the majority of the antioxidant activities were detected in the ethyl acetate and butanol fractions in which phenolic ingredients were abundant. The ethyl acetate and butanol fractions of hwanggeumchal sorghum and the ethyl acetate fraction of glutinous sorghum showed higher antioxidant activity than that of ${\alpha}$-tocopherol. Both ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods demonstrated that these organic solvent fractions could inhibit lipid peroxidation. The ethyl acetate fractions from hwanggeumchal sorghum, glutinous sorghum, and barnyard millet grains could suppress tertiary-butyl hydroperoxide (TBHP)-induced apoptotic events, including sub-G1 peaks, ${\Delta}{\Psi}m$ loss, activation of caspase-9 and caspase-3, and cleavage of PARP and lamin B, in human HL-60 cells. These results show that the grains of hwanggeumchal sorghum (Sorghum bicolor L. Moench cv. Hwanggeumchalsusu), glutinous sorghum (Sorghum bicolor L. Moench cv. Chalsusu), and barnyard millet (Echinochloa esculenta) possess efficient antioxidant activity, which could protect cells from oxidative stress-mediated cytotoxicity.