• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.105-105
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• 2023

Heavy metals, including lead (Pb) toxicity, are increasing in soil and are considered toxic in small amounts. Pb contamination is mainly caused by industrialization - smelting, mining. Agricultural practices - sewage sludge, pests and urban practices - lead paint. It can seriously damage and threaten crop growth. Pb can adversely affect plant growth and development by affecting the photosystem, cell membrane integrity, and excessive production of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂)andsuperoxide(O₂.-). NO is produced via enzymatic and non-enzymatic antioxidants to scavenge ROS and lipid peroxidation substrates in terms of protecting cells from oxidative damage. Thus, NO improves ion homeostasis and confers resistance to metal stress. Our results here suggest that exogenous NO may aid in better growth under lead stress. These enhancements may be aided by NO's ability in sensing, signaling and stress tolerance in plants under heavy metal stress in combination with lead stress. Our results show that GSNO has a positive effect on soybean seedling growth in response to axillary pressure and that NO supplementation helps to reduce chlorophyll maturation and relative water content in leaves and roots following strong burst under lead stress. GSNO supplementation (200 µM and 100 µM) reduced compaction and approximated oxidative damage of MDA, proline and H₂O₂. Under plant tension, a distorted appearance was found in the relief of oxidative damage by ROS scavenging by GSNO application. In summary, modulation of these NO, PCS and prolongation of metal past reversing GSNO application confirms the detoxification of ROS induced by toxic metal rates in soybean. In summary, these NO, PCS and metal traditionally sustained rates of reverse GSNO application confirm the detoxification of ROS induced by toxic metal rates in soybean.

• Composites Research
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• v.37 no.1
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• pp.7-14
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• 2024

Due to the structural characteristic of a double roller, the double roller can have various deformation behaviors depending on a gap block design, even if dimensions and loading conditions for the double roller are the same. Based on this feature, we propose a strategy for designing the gap block of the carbon-fiber reinforced plastic (CFRP) double roller to minimize defects (e.g., sagging and wrinkling), which can be raised during the product conveying process, with the pursue of the lightweight design. In the suggested strategy, analysis cases are first selected by considering main design parameters and engineering tolerances of the gap block, and then deformation behaviors of these selected cases are extracted using the finite element method (FEM). Here, to obtain the optimal gap block parameters that satisfy the purpose of this study, deformation deviations in the contact area are calculated and compared using the extracted deformation behaviors. Note that the contact area in this work is located between the product and the roller. As a result, through the design method of the gap block proposed in this work, it is possible to construct the CFRP double roller that can significantly decrease the defects without changing the overall sizes of the roller. A detailed method is suggested herein, and the results are evaluated in a numerical way.

• Biomolecules & Therapeutics
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• v.32 no.3
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• pp.329-340
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• 2024

Mangiferin is a kind of natural xanthone glycosides and is known to have various pharmacological activities. However, since the beneficial efficacy of this compound has not been reported in retinal pigment epithelial (RPE) cells, this study aimed to evaluate whether mangiferin could protect human RPE ARPE-19 cells from oxidative injury mimicked by hydrogen peroxide (H₂O₂). The results showed that mangiferin attenuated H₂O₂-induced cell viability reduction and DNA damage, while inhibiting reactive oxygen species (ROS) production and preserving diminished glutathione (GSH). Mangiferin also antagonized H₂O₂-induced inhibition of the expression and activity of antioxidant enzymes such as manganese superoxide dismutase and GSH peroxidase, which was associated with inhibition of mitochondrial ROS production. In addition, mangiferin protected ARPE-19 cells from H₂O₂-induced apoptosis by increasing the Bcl-2/Bax ratio, decreasing caspase-3 activation, and blocking poly(ADP-ribose) polymerase cleavage. Moreover, mangiferin suppressed the release of cytochrome c into the cytosol, which was achieved by interfering with mitochondrial membrane disruption. Furthermore, mangiferin increased the expression and activity of heme oxygenase-1 (HO-1) and nuclear factor-erythroid-2 related factor 2 (Nrf2). However, the inhibition of ROS production, cytoprotective and anti-apoptotic effects of mangiferin were significantly attenuated by the HO-1 inhibitor, indicating that mangiferin promoted Nrf2-mediated HO-1 activity to prevent ARPE-19 cells from oxidative injury. The results of this study suggest that mangiferin, as an Nrf2 activator, has potent ROS scavenging activity and may have the potential to protect oxidative stress-mediated ocular diseases.

• Korean Journal of Food Science and Technology
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• v.50 no.4
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• pp.383-390
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• 2018

Most neurodegenerative diseases are known to be influenced by oxidative stress. We investigated the anti-oxidative activity of the concentrate of fermented wild ginseng root culture (HLJG0701) containing ginsenosides Rg5 and Rk1. HLJG0701 showed effective DPPH and ABTS radical scavenging ability ($IC_{50}$: 16- and 4-fold dilution, respectively) and was inhibited dose-dependently by the $FeSO_4$-induced lipid peroxidation group (8- and 4-fold dilution: 2.3 and 1.5 nM, respectively). In MTT and LDH assays, 8-, 16-, 32- and 64-fold diluted HLJG0701 significantly increased cell viability by 70, 53, 35, and 26%, respectively. LDH released by HLJG0701 was reduced 1.3-fold with 8-fold diluted HLJG0701 compared to the $H_2O_2$-treated control. In addition, the inhibitory effect of HLJG0701 on oxidative stress in PC12 cells was confirmed by DCF-DA analysis (16-, 4-fold diluted HLJG0701: 50 and 68% ROS inhibition, respectively), TBARS (16- and 4-fold diluted HLJG0701: 50.7 and 46.5% inhibition, respectively), GPx (16- and 4-fold diluted HLJG0701: 133.3 and 227.3% release, respectively), and SOD analysis (16- and 4-fold diluted HLJG0701: 118.2 and 218.2% release, respectively). These results suggested that HLJG0701 protects neuronal cells by its anti-oxidative effects and hence can be a potential preventive material against neurodegenerative diseases.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.2
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• pp.161-167
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• 2013

The aim of this study was to investigate the protective effects of methanolic extract from perilla (Perilla frutescens Britt var. japonica) leaves (PLME) on oxidative injury from hydrogen peroxide ($H_2O_2$) in human HaCaT keratinoctyes. Cells were co-incubated with various concentrations (0~200 ${\mu}g/mL$) of PLME for 24 hr, and then exposed to $H_2O_2$ (500 ${\mu}M$) for 4 hr. $H_2O_2$ significantly decreased cell viability (p<0.05). However, PLME provided protection from $H_2O_2$-induced HaCaT cell oxidation in a dose-dependent manner. To further investigate the protective effects of PLME on $H_2O_2$-induced oxidative stress in HaCaT cells, the cellular levels of lipid peroxidation, and antioxidant enzymes (including superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and catalase (CAT)) were measured. PLME decreased cellular levels of lipid peroxidation, and also increased the activities of antioxidant enzymes. In addition, the antioxidant activities of PLME were also determined by DPPH and hydroxyl (${\cdot}OH$) radical scavenging assay, and major antioxidant compounds of PLME were measured by colorimetric methods. DPPH and ${\cdot}OH$ radical scavenging activities of PLME increased in a dose dependent manner and was similar to the DPPH scavenging activity of ascorbic acid at 50 ${\mu}g/mL$; however PLME activities were stronger than ascorbic acid (50 ${\mu}g/mL$) in the ${\cdot}OH$ scavenging assay. The amounts of antioxidant compounds, including total polyphenolics, total flavonoids, and total ascorbic acid from PLME were $52.2{\pm}1.1$ mg gallic acid (GAE)/g, $33.7{\pm}4.7$ mg rutin (RUE)/g, and $17.0{\pm}0.5$ mg ascorbic acid (AA)/g, respectively. These results suggest that PLME has a strong free radical-scavenging activity and a protective effect against $H_2O_2$-induced oxidative stress in the keratinocytes.

• Composites Research
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• v.14 no.3
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• pp.18-31
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• 2001

Interfacial and microfailure properties of the modified steel, carbon and glass fibers/cement composites were investigated using electro-pullout test under tensile and compressive tests with acoustic emission (AE). The hand-sanded steel composite exhibited higher interfacial shear strength (IFSS) than the untreated and even neoalkoxy zirconate (Zr) treated steel fiber composites. This might be due to the enhanced mechanical interlocking, compared to possible hydrogen or covalent bonds. During curing process, the contact resistivity decreased rapidly at the initial stage and then showed a level-off. Comparing to the untreated case, the contact resistivity of either Zr-treated or hand-sanded steel fiber composites increased to the infinity at latter stage. The number of AE signals of hand-sanded steel fiber composite was much more than those of the untreated and Zr-treated cases due to many interlayer failure signals. AE waveforms for pullout and frictional signals of the hand-sanded composite are larger than those of the untreated case. For dual matrix composite (DMC), AE energy and waveform under compressive loading were much higher and larger than those under tensile loading, due to brittle but well-enduring ceramic nature against compressive stress. Vertical multicrack exhibits fur glass fiber composite under tensile test, whereas buckling failure appeared under compressive loading. Electro-micromechanical technique with AE can be used as an efficient nondestructive (NDT) method to evaluate the interfacial and microfailure mechanisms for conductive fibers/brittle and nontransparent cement composites.

• Journal of Life Science
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• v.20 no.2
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• pp.281-291
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• 2010

We investigated the antioxidant effects of hederagenin 3-O-b-D-glucopyranosyl($1{\rightarrow}3$)-a-L-rhamnopyranosyl($1{\rightarrow}2$)-a-L-arabinopyranoside (HDL) isolated from root bark of Ulmus davidiana on the activity of enzymes related to reactive oxygen species (ROS) in human osteosarcoma U2OS cells. Cobalt chloride ($CoCl_2$), a transition metal, was used as an inducer of oxidative stress, generating hydrogen peroxide ($H_2O_2$) via increasing xanthine oxidase (XO) activity. The increased levels of $H_2O_2$, XO, ferritin, and ferritin iron by $CoCl_2$ were diminished effectively by co-treatment with HDL in U2OS cells. Furthermore, decreased levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) by $CoCl_2$ were highly increased by co-treatment with HDL in U2OS cells; however, the levels of glutathione peroxidase (GPx) did not change. The increased contents of TBARS related to lipid peroxidation were significantly reduced by HDL in U2OS cells. The concentration of GSH changed in a pattern that went against regulated TBARS by $CoCl_2$ and HDL. We examined the expression of p53, $p21^{CIP1/WAF1}$, and $p27^{KIP1}$ proteins related to oxidative stress and cell cycle regulation. As a result, the expression of $p27^{KIP1}$ modulated by $CoCl_2$ was not changed by HDL. However, the expression of p53 and $p21^{CIP1/WAF}$ increased by $CoCl_2$ was reduced by HDL in U2OS cells. Together with alteration of p53 and $p21^{CIP1/WAF1}$ proteins, the accumulated cells at G1 phase by $CoCl_2$ was decreased by HDL in U2OS cells. Our data suggests that HDL inhibits $CoCl_2$-generated ROS in U2OS cells, providing potentially new antioxidant compounds that are isolated from natural products.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.170-176
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• 2014

In this study, the anti-oxidative and anti-inflammatory activities of Euptelea pleiosperma ethanol extract (EPEE) were evaluated using in vitro assays and cell culture model systems. EPEE possessed a more potent scavenging activity against 1,1-diphenyl-2-picryl hydrazyl than the ascorbic acid used as a positive control. EPEE effectively suppressed lipopolysaccharide (LPS), in addition to hydrogen peroxide induced reactive oxygen species on RAW 264.7 cells. Furthermore, EPEE induced the expression of the anti-oxidative enzyme heme oxygenase 1 (HO-1) and its upstream transcription factor, nuclear factor-E2-related factor 2 (Nrf2), dose and time dependently. The modulation of HO-1 and Nrf2 expression might be regulated by mitogen-activated protein kinases and phosphatidyl inositol 3 kinase/Akt as their upstream signaling pathways. On the other hand, EPEE inhibited LPS induced nitric oxide (NO) formation without cytotoxicity. Suppression of NO formation was the result of the down regulation of inducible NO synthase (iNOS) by EPEE. Suppression of NO and iNOS by EPEE may be modulated by their upstream transcription factor, nuclear factor ${\kappa}B$, and AP-1 pathways. Taken together, these results provide important new insights into E. pleiosperma, namely that it possesses anti-oxidative and anti-inflammatory activities, indicating that it could be utilized as a promising material in the field of nutraceuticals.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2007.11a
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• pp.79-92
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• 2007

Oxidative stress have known to be a risk factor for the degenerative processes and closely related to a lot of diseases. It is well established that antioxidants are good in protection and therapeutic means against oxidative damage. There is increasing interest in natural antioxidants and many natural antioxidants have been found and utilized as the possible protection for various diseases and skin aging. We have screened natural antioxidant agents for cosmeceuticals, nutraceuticals, and drugs as therapeutic and preventive means against oxidative stress, and have developed a number of novel antioxidants from various natural sources. A novel melanin synthesis inhibitor, Melanocin A, isolated from the metabolite of a fungal strain Eupenicillium shearii F80695 inhibited mushroom tyrosinase and melanin biosynthesis of B16 melanoma cells with $IC_{50}$ value of 9.0 nM and MIC value of $0.9\;{\mu}M$, respectively. Melanocin A also exhibited potent antioxidant activity by scavenging of DPPH and superoxide anion radicals. UV was found to increase the level of hydrogen peroxides and other reactive oxygen species (ROS) in skin tissues. This increase in ROS may not only alter the structure and function of many genes and proteins directly but may also modulate their expressions through signal transduction pathways and, ultimately, lead to skin damage. We investigated the effect of Melanocin A on UV-induced premature skin aging. Firstly, the effect of Melanocin A on UV-induced matrix metalloproteinase (MMP)-9 expression in an immortalized human keratinocyte cell line, HaCaT in vitro was investigated. Acute UV irradiation induced MMP-9 expression at both the mRNA and protein levels and Melanocin A suppressed this expression in a dose-dependent manner. We then investigated UV-induced skin changes in hairless mice in vivo by Melanocin A. Chronic exposure of hairless mouse dorsal skin to UV increased skin thickness and induced wrinkle formation and the gelatinase activities of MMP-2 and MMP-9. Moreover, Melanocin A significantly suppressed UV-induced morphologic skin changes and MMP-2 and MMP-9 expression. These results show that Melanocin A can prevent the harmful effects of UV that lead to skin aging. Therefore, we suggest that Melanocin A should be viewed as a potential therapeutic agent for preventing and/or treating premature skin aging. Terrein is a bioactive fungal metabolite isolated from Penicillium species. Terrein has a relatively simple structure and can be easily synthesized. However, the biologic effects of terrein are comparatively unknown. We found for the first time that terrein potently inhibit melanin production in melanocytes and has a strong hypopigmentary effect in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment of Mel-Ab cells with terrein (10-100 mM) for 4 days significantly reduced melanin levels in a dose-dependent manner. In addition, terrein at the same concentration also reduced tyrosinase activity. We then investigated whether terrein influences the extracellular signal-regulated protein kinase (ERK) pathway and the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. Terrein was found to induce sustained ERK activation and MITF down-regulation, and luciferase assays showed that terrein inhibits MITF promoter activity in a dose-dependent manner. To elucidate the correlation between ERK pathway activation and a decreased MITF transcriptional level, PD98059, a specific inhibitor of the ERK pathway, was applied before terrain treatment and found to abrogate the terrein-induced MITF attenuation. Terrein also reduced the tyrosinase protein level for at least 72 h. These results suggest that terrain reduces melanin synthesis by reducing tyrosinase production via ERK activation, and that this is followed by MITF down-regulation.

• Journal of Nutrition and Health
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• v.52 no.1
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• pp.26-35
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• 2019

Purpose: The aim of this study was to estimate the antioxidant activities of 50%, 70%, and 100% ethanol extracts of Lycium barbarum leaf and chlorophyll removal extract. Methods: The antioxidant activities were estimated by measuring total polyphenol content and by assays of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfate) (ABTS) radical scavenging activities and ferric reducing antioxidant power (FRAP). In addition, reactive oxygen species (ROS) production, DNA fragmentation, and antioxidant enzyme (superoxide dismutase and catalase) activities of the extracts were measured in hydrogen peroxide ($H_2O_2$)-stressed HepG2 cells. Results: The total polyphenol content, DPPH and ABTS radical scavenging activities, and FRAP value of the extracts increased in an ethanol concentration-dependent manner. The antioxidant activities of the chlorophyll-removal extracts were much higher than those of the chlorophyll-containing extracts. Cytotoxicity was not observed in HepG2 cells with extracts up to $1,000{\mu}g/mL$. All extracts inhibited ROS production in a concentration-dependent manner from $31.3{\mu}g/mL$ and inhibited DNA damage at $250{\mu}g/mL$. The SOD and catalase activities of cell lines treated with the extracts and $H_2O_2$ were similar to those of normal cells, indicating a strong protective effect. Conclusion: Lycium barbarum leaf extracts had high antioxidant activities and protected $H_2O_2$-stressed HepG2 cells. Since the chlorophyll-removal extract exhibited higher antioxidant activities than the chlorophyll-containing ones and the cytoprotective effect was similar, chlorophyll removal extract of Lycium barbarum leaf could be developed as ingredients of functional food and cosmetics.