• Elastomers and Composites
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• 제55권2호
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• pp.95-102
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• 2020

Currently, peroxide cure is a widely used cure system for rubber materials. To improve its effectivity, co-agents are used to enhance the peroxide efficiency and mechanical properties of rubber materials. Co-agents are multifunctional organic compounds that are highly reactive towards free radicals. These co-agents provide higher cross-link densities for a given peroxide concentration and improve the mechanical properties of peroxide-cured rubber composites. In this study, trimethylolpropane trimethacrylate (TMPTMA) and high vinyl 1,2-polybutadiene (HVPBD) were used as co-agents. In order to obtain a concentration that achieves a favorable balance between mechanical properties and co-agent concentration, this research investigated the effects of co-agent content on the curing characteristics, chemical structures, and mechanical properties of HNBR composites. Additionally, the heat aging properties and compression sets of HNBR composites were investigated. Based on the results, we found that the HNBR composites with TMPTMA co-agents exhibited higher Shore A hardness and 10% modulus and better heat aging resistance and compression set than that of the HVPBD co-agent. The heat aging resistance and compression set deteriorated with increasing HVPBD content.

• 약학회지
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• 제49권2호
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• pp.174-179
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• 2005

The human skin is constantly exposed to environmental irritants such as ultraviolet, smoke, chemicals. Free radicals and reactive oxygen species (ROS) caused by these environmen tal facts play critical roles in cellular damage. These irritants are in themselves damaging to the skin structure but they also participate the immensely complex inflammatory reaction. The purpose of this study was to investigate the skin cell protective effect of Campsis grandiflora extract on the UVB-irradiated human dermal fibroblasts (HDFs). We tested free radical and superoxide scavenging effect in vitro. C. grandiflora extracts had potent radical scavenging effect by 82% at $100{\mu}g/ml$, respectively. For testing intracellular ROS scavenging activity the cultured HDFs were analyzed by increase in DCF fluorescence upon exposure to UVB 20 $MJ/cm^2$ after treatment of C.grandiflora extracts. The results showed that oxidation of CM-DCFDA was inhibited by C.grandiflora extracts effectively and C.grandiflora extracts has a potent free radical scavenging activity in UVB- irradiated HDFs. In ROS imaging using confocal microscope we visualized DCF fluorescence in HDFs directly. In conclusion, our results suggest that C.grandiflora can be effectively used for the prevention of UV-induced adverse skin reactions such as radical production, and skin cell damage.

• Archives of Pharmacal Research
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• 제26권6호
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• pp.458-462
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• 2003

The antioxidant activity of the stem bark from Albizzia julibrissin was evaluated for its potential to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, to inhibit the generation of the hydroxyl radical ($\cdot OH$), total reactive oxygen species (ROS) and to scavenge authentic peroxynitrites ($ONOO^{-}$). The methanol extract of A. julibrissin exhibited strong antioxidant activity in the tested model systems. Therefore, it was further fractionated using several solvents. The antioxidant activity of the individual fractions were in the order of ethyl acetate (EtOAc) ＞ n-butanol (n-BuOH) ＞ dichloromethane ($CH_2 CI-2$) ＞ and water ($H_2O$). The ethyl acetate soluble fraction, which exhibited strong antioxidant activity, was further purified by repeated silicagel, Sephadex LH-20 and RP-18 gel column chromatography. Sulfuretin (1) and 3 ,4 ,7-trihydroxyflavone (2) were isolated as the active principles. Compounds 1 and 2 exhibited good activity in all tested model systems. Compound 1 exhibited five times more inhibitory activity on the total ROS than Trolox. Compound 2 showed six times stronger DPPH radical scavenging activity than L-ascorbic acid. These results show the possible antioxidant activity of the A. julibrissin crude extract and its major constituents.

• 한국수소및신에너지학회논문집
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• 제27권2호
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• pp.220-229
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• 2016

A numerical study on lifted flame structure in impinging jet geometry with syngas composition ratio was investigated. The numerical calculations including chemical kinetic analysis were conducted using SPIN application of the CHEMKIN Package with Davis-Mechanism. The flame temperature and velocity profiles were calculated at the steady state for one-dimensional stagnation flow geometry. Syngas mixture compositions were adjusted such as $H_2:CO=10:90(10P)$, 20 : 80 (20P), 30 : 70 (30P), 40 : 60 (40P), 50 : 50 (50P). As composition ratios are changed from 10P to 50P, the axial velocity and flame temperature increase because the contents of hydrogen that have faster burning velocity increase. This phenomenon is due to increase in good reactive radicals such as H, OH radical. As a result of active reactivity, the burning velocity is more faster and this is confirmed by numerical methods. Consequently, combustion reaction zone was moved to burner nozzle.

• Applied Biological Chemistry
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• 제47권2호
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• pp.279-282
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• 2004

An antioxidant was isolated from Korean mistletoe (Viscum album var. coloratum) by consecutive purification using silica gel, Sephadex LH-20, and RP-HPLC. The active principle was identified as homo-flavoyadorinin-B (3',7-dimethoxyluteolin-4'-O-[apiosyl $(1{\rightarrow}2)$ glucoside]) by spectral analyses. It inhibited 74.6% of hydroxyl radical and 30.6% of superoxide anion radical at 0.01 mM; however, th~compound did not show any scavenging activity against hydrogen peroxide radical. At 0.1 mM, above compound scavenged superoxide anion radical about twice as effective as positive controls, BHT and ${\alpha}-tocopherol$. Radical scavenging activities of homo-flavoyadorinin-B on DPPH, hydroxyl, and hydrogen peroxide radicals were almost same with those of positive controls.

• 생약학회지
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• 제35권1호통권136호
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• pp.28-34
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• 2004

DNA damage induced by reactive oxygen species (ROS) seems to play an important role in the induction of mutation and cancer. Hydrogen peroxide $(H_2O_2)$ has been shown to induce a variety of genetic alterations, probably by the generation of hydroxyl radicals via Fenton reaction. In this study, we examined the ability of medicinal herbs in the suppression of $H_2O_2$-induced mutagenesis. Human fibroblast GM00637 cells were treated with $H_2O_2$ in the presence or absence of medicinal herbs, and $H_2O_2$-induced mutant frequency was measured at the hypoxanthine guanine phosphoribosyl transferase (HPRT) locus. Treatment of cells with various doses of $H_2O_2$ caused a significant increase of the HPRT mutant frequency. However, pretreatment of cells with several medicinal herbs reduced $H_2O_2$-induced mutant frequency. The strong antimutagenic effects were observed from the methylene chloride and ethyl acetate fractions of Selaginella tamariscina, Panax ginseng, and Angelica acutiloba; ethyl acetate fractions of Rehmania glutinosa, Leonurus sibiricus, Curcuma zedoaria and Commiphora molmol; butanol fractions of Scutellaria barbata, Tribulus terrestris, Curcuma zedoaria, Cyperus rotundus and Carthamus tinctorius, which were more than 60% inhibition of $H_2O_2$-induced mutant frequency at the HPRT locus.

• Journal of Applied Biological Chemistry
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• 제64권3호
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• pp.237-244
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• 2021

Camellia sinensis, Green tea, contains phenolic compounds that act to scavenge reactive oxygen species (ROS), such as catechin, epicatechin, etc. In contrast with the tea leaf, the bioactivity of its fruit and the fruit peels remains still unclear. This study focused on the effects of fruit and fruit peels of C. sinensis (FC and PC) against oxidative DNA damage in NIH/3T3 cells. The scavenging effects of FC and PC on ROS were assessed using 1,1-diphenyl-2-picryl hydrazyl or 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radicals. The measurement of ROS in cellular levels was conducted by DCFDA reagent and the protein expression of γ-H2AX, H2AX, cleaved caspase-3, p53, and, p-p53 was analyzed by immunoblotting. The gene expressions of p53 and H2AX were assessed using polymerase chain reaction techniques. The major metabolites of FC and PC were quantitatively measured analyzed and the amounts of phenolic compounds and flavonoids in PC were greater than those in FC. Further, PC suppressed ROS production, which protects the oxidative stress-induced DNA damage through reducing H2AX, p53, and caspase-3 phosphorylation. These results refer that the protective effects of FC and PC are mediated by inhibition of p53 signaling pathways, probably via the bioactivity of phenolic compounds. Thus, FC and PC can serve as a potential antioxidant in DNA damage-associated diseases.

• 상하수도학회지
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• 제34권6호
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• pp.445-462
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• 2020

Industrial wastewater often contains a number of recalcitrant organic contaminants. These contaminants are hardly degradable by biological wastewater treatment processes, which requires a more powerful treatment method based on chemical oxidation. Advanced oxidation technology (AOT) has been extensively studied for the treatment of nonbiodegradable organics in water and wastewater. Among different AOTs developed up to date, ozonation and the Fenton process are the representative technologies that widely used in the field. Based on the traditional ozonation and the Fenton process, several modified processes have been also developed to accelerate the production of reactive radicals. This article reviews the chemistry of ozonation and the Fenton process as well as the cases of application of these two AOTs to industrial wastewater treatment. In addition, research needs to improve the cost efficiency of ozonation and the Fenton process were discussed.

• 한국식품위생안전성학회:학술대회논문집
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• 한국식품위생안전성학회 2002년도 춘계학술발표대회 및 심포지움
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• pp.138-138
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• 2002

Oxidative stress has been associated with a number of diseases in human. Among the sources that can generate oxidative stress, it has been reported that iron can generate reactive oxygen species (ROS)with thiol. In iron overload state, increased thiol levels in plasma appeared to be associated with human mortality. In this study we examined whether iron could interact with thiols in plasma, generating ROS. In human plasma, unlike with Fe(III), Fe(II) increased lucigenin-enhanced chemiluminescence in concentration-dependent manner, and this was inhibited by SOD. Boiling of plasma did not affect chemiluminescence induced by Fe(II). Hovever, thiol depletion in plasma by pretreatment with N-ethylmaleimide (NEM)decreased Fe(II)-induced chemiluminescence significantly, suggesting that Fe(II) generated superoxide anion by the nonenzymatic reaction with plasma thiol. Consistent with this findings, albumin, the major thiol contributor in plasma, also generated ROS with Fe(II) and this generation was inhibited by pretreatment with NEM. Treatment with Fe(II) to plasma resulted un significant reduction of oxygen radical absorbance capacity (ORAC) value, suggest that total antioxidant capacity could diminished in iron overload state. In conclusion, In iron overload state, plasma may be affected by oxidative stress mediated by nonenzymatic reaction of Fe (II)with plasma thiol.

• International Journal of Industrial Entomology and Biomaterials
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• 제46권2호
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• pp.25-33
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• 2023

The liver, a multifunctional organ, plays a vital role in maintaining overall health and well-being by regulating metabolism, detoxification, nutrient storage, hormone balance, and immune function. Liver diseases, such as hepatitis, cirrhosis, fatty liver disease, and liver cancer, have significant clinical implications and remain a global health concern. This article reviews the therapeutic potential of silkworm larvae (Bombyx mori) and explores their underlying molecular mechanisms in protecting against liver diseases. Silkworm larvae are rich in proteins, vitamins, minerals, and n-3 fatty acids, making them a promising candidate for therapeutic applications. The anti-inflammatory mechanisms of silkworm larvae involve modulating the production of cytokine such as TNF-α and interleukins, inflammatory enzymes including cyclooxygenase-2 and macrophage polarization, thereby attenuating liver inflammation. Silkworm larvae also exhibit anti-oxidative effects by scavenging free radicals, reducing intracellular reactive oxygen species and enhancing the liver's antioxidant defense system. Moreover, silkworms have been reported to decrease the serum alcohol concentration and lipid accumulation. Understanding the therapeutic properties of silkworm larvae contributes to the development of innovative strategies for liver injury prevention and treatment. Further research is warranted to elucidate the precise signaling pathways involved in the anti-inflammatory and anti-oxidative effects of silkworm larvae, paving the way for potential therapeutic interventions in liver diseases.