• Journal of the Korean Applied Science and Technology
• /
• v.34 no.2
• /
• pp.349-356
• /
• 2017

OH radical generation is one of the common method to evaluate photocatalytic activity. In many of previous studies, only the UV(Ultraviolet) light was applied to test photocatalytic ability of $TiO_2$ nanotubes by studying probe compound(4-Chlorobenzoic acid) concentration change in solution. Also, $TiO_2$ nanotubes were found to show some electrochemical characteristics when the flow of electric current was applied. In this study, the flow of electric current and UV light were applied at the same time to determine whether electrochemical characteristics of $TiO_2$ nanotube plate can give synergetic effect on the photocatalytic activity. $TiO_2$ nanotube was grown on Ti by anodic oxidation to create $TiO_2$ nanotube plate which can be used as a photocatalyst and a electrode that can undergo AOP(Advanced Oxidation Process) for water treatment. Probe compound solution was prepared using 4-chlorobenzoic acid and $H_2O$ as a solvent. NaCl was added to give conductivity to work as electrolyte. As a result, enough level of electric current flow was found to give synergetic photocatalytic effect which can be used for efficient AOP water treatment method.

• Environmental Mutagens and Carcinogens
• /
• v.19 no.2
• /
• pp.116-121
• /
• 1999

Quercetin and its glycosides showed a strong free radical scavenging effect to DPPH radical generation. However, there were not big differences between quercetin aglycone and glycosides under experimental condition of this study. On the other hand, quercetin had pro-oxidant effect in bleomycin-dependent DNA assay. Quercetin aglycone and its glycosides, quercitrin inhibited $H_2$$O_2$- induced DNA damage in CHL cells. They also have an anticlastogenicity toward DNA breakage agent by radical generation like bleomycin. These results indicate that quercetin aglycone and its glycosides are capable of protecting the free radical generation induced by reactive oxygen species like $H_2$$O_2$. The mechanism of inhibition in hydrogen peroxide-induced genotoxicity may be due to their free radical scavenging properties. Therefore, quercetin aglycone and its glycosides may be useful chemopreventive agents by protecting of free radical generation which are involved in carcinogenesis and aging. However, quercetin and its glycosides must also carefully examined for pro-oxidant properties before being proposed for use in vivo.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.7
• /
• pp.675-680
• /
• 2009

There is considerable interest in the isolation of potent radical scavenging compounds from natural resources to treat diseases involving oxidative stress. In this report, four new fungal metabolites including one new bisdihydroanthracenone derivative (1, eurorubrin), two new seco-anthraquinone derivatives [3, 2-O-methyl-9-dehydroxyeurotinone and 4, 2-O-methyl-4-O-(${\alpha}$-D-ribofuranosyl)-9-dehydroxyeurotinone], and one new anthraquinone glycoside [6,3-O-(${\alpha}$-D-ribofuranosyl)-questin], were isolated and identified from Eurotium rubrum, an endophytic fungal strain that was isolated from the inner tissue of the stem of the marine mangrove plant Hibiscus tiliaceus. In addition, three known compounds including asperflavin (2), 2-0-methyleurotinone (5), and questin (7) were also isolated and identified. Their structures were elucidated on the basis of spectroscopic analysis. All of the isolated compounds were evaluated for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity.

• ALGAE
• /
• v.21 no.1
• /
• pp.149-156
• /
• 2006

The aim of the present study was to evaluate the antioxidant activity of red algae in Jeju Island. The algal extracts were obtained with MeOH and fresh water at 20 and 70°C, and screened for antioxidant activities using hydroxyl radical (HO·), superoxide anion (O2–), hydrogen peroxide (H2O2) and DPPH free radical scavenging assays. Among them, Gracilaria verrucosa methanolic extract at 20°C (20ME, 96.85%), G. textorii aqueous extract at 20°C (20AE, 88.01%), Grateloupia filicina 20AE (85.35%), and Polysiphonia japonica 20ME (94.92%) exhibited the highest scavenging activities against HO·, O2–, H2O2, and DPPH free radicals, respectively. Moreover, P. japonica (20ME and 70ME) is correlated between DPPH free radical scavenging activity and polyphenolic contents. These results indicate that some red algae in Jeju Island could be potential candidates for development of antioxidants.

• Toxicological Research
• /
• v.18 no.2
• /
• pp.159-165
• /
• 2002

Recently, we reported (korean J. Biomed. Lab. Sci., 6(4): 245-251, 2000) that cyclohexane (l.56 g/kg of body wt., i.p.) administration led to lung injury in rats. However the detailed mechanism remain to be elucidated. This study was designed to clarify the mechanism of lung damage induced by cyclohexane in rats. First, lung damage was assessed by quantifying bronchoalveolar lavage fluid (BAL) protein content as well us by histopathological examination. Second, activities of serum xanthine oxidase (XO), pulmonary XO and oxygen free radical scavenging enzymes. XO tope conversion (O/D + O, %) ratio and content of reduced glutathione (GSH) were determined. In the histopathological findings, the vasodilation, local edema and hemorrhage were demonstrated in alveoli of lung. And vascular lumens filled with lipid droplets, increased macrophages in luminal margin and increased fibroblast-like interstitial cells in interstitial space were observed in electron micrographs. The introperitoneal treatment of cyclohexane dramatically increased BAL protein by 21-fold compared with control. Cyclohexane administration to rats led to a significant rise of serum and pulmonary XO activities and O/D + O ratio by 47%,30% and 24%, respectively, compared witれ control. Furthermore, activities of pulmonary oxygen free radical scavenging enzymes such as superoxide dismutase, glutathione peroxidase and glutathione S-transferase, and GSH content were not found to be statistically different between control and cyclohexane-treated rats. These results indicate that intraperitoneal injection of cyclohexane to rats may induce the lipid embolism in pulmonary blood vessel and lead to the hypoxia with the ensuing of oxygen free radical generation, and which may be responsible for the pulmonary injury.

• Preventive Nutrition and Food Science
• /
• v.19 no.3
• /
• pp.129-135
• /
• 2014

The protective role of phloroglucinol against oxidative stress and stress-induced premature senescence (SIPS) was investigated in vitro and in cell culture. Phloroglucinol had strong and concentration-dependent radical scavenging effects against nitric oxide (NO), superoxide anions ($O_2{^-}$), and hydroxyl radicals. In this study, free radical generators were used to induce oxidative stress in LLC-PK1 renal epithelial cells. Treatment with phloroglucinol attenuated the oxidative stress induced by peroxyl radicals, NO, $O_2{^-}$, and peroxynitrite. Phloroglucinol also increased cell viability and decreased lipid peroxidation in a concentration-dependent manner. WI-38 human diploid fibroblast cells were used to investigate the protective effect of phloroglucinol against hydrogen peroxide ($H_2O_2$)-induced SIPS. Phloroglucinol treatment attenuated $H_2O_2$-induced SIPS by increasing cell viability and inhibited lipid peroxidation, suggesting that treatment with phloroglucinol should delay the aging process. The present study supports the promising role of phloroglucinol as an antioxidative agent against free radical-induced oxidative stress and SIPS.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.4
• /
• pp.719-730
• /
• 2014

The hot water extract from Artemisia capillaris fermented with Hericium erinaceum mycelium (AC-HE) were assessed for the protection against oxidative modification of biological macromolecules and cell death. Antioxidant activity of AC-HE evaluated using 2,2-diphenyl-1-picrylhydrazyl radical, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical and peroxyl radical scavenging assays. AC-HE showed 61.73% DPPH radical scavenging activity at $500{\mu}g/mL$, 97.39% ABTS radical scavenging activity at $250{\mu}g/mL$, and 44.18% peroxyl radical scavenging activity at $100{\mu}g/mL$. AC-HE were shown to significantly inhibited DNA strand breakage induced by peroxyl radical. AC-HE also prevented peroxyl radical-mediated human serum albumin modification. AC-HE effectively inhibited $H_2O_2$ induced cell death and significantly increased of the 11.47% cell survival at $100{\mu}g/mL$. AC-HE also decreased intracellular reactive oxygen species (ROS) levels in $H_2O_2$-treated cells. The results suggested that AC-HE can contribute to antioxidant and protected cells from oxidative stress-induced cell injury.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.785-789
• /
• 2008

The present study is the first report of utilizing $TiO_2$ photocatalyst to analytically calibrate the hydroperoxyl radical ($HO_2\;^{\cdot}$). An in-situ calibration method of $HO_2\;^{\cdot}$ is proposed for air monitoring by using an 2-methyl-6-(pmethoxyphenyl)- 3,7-dihydroimidazo-[1,2-a]pyrazin-3-one (MCLA)-chemiluminescence (CL) technique. In this method, $HO_2\;^{\cdot}$($pK_a$ = 4.80) is produced by the ultraviolet (UV) photolysis of immobilized $TiO_2$ using a constant flow rate of air equilibrated water, in which $HO_2\;^{\cdot}$ is controlled by using various lengths of knotted tubing reactor (KTR). The principle of the proposed calibration is based on the experimentally determined halflife ($t_{1/2}$) of $HO_2\;^{\cdot}$ and its empirically observed pH-dependent rate constant, $k_{obs}$, at a given pH. The concentration of $HO_2\;^{\cdot}$/$O_2\;^{\cdot}$− is increased as pH increases. This pH dependence is due to the different disproportionative reactivities between $HO_2\;^{\cdot}$/$O_2\;^{\cdot}$− and $HO_2\;^{\cdot}$/$O_2\;^{\cdot}$−. Experimental results indicate the practical feasibility of the approach, producing very promising method.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.10
• /
• pp.2873-2876
• /
• 2010

Excess free iron generates oxidative stress that may contribute to the pathogenesis of various causes of neurodegenerative diseases. Previous studies have shown that one of the primary causes of increased brain iron may be the release of excess iron from intracellular iron storage molecules. In this study, we attempted to characterize the oxidative damage of DNA induced by the reaction of ferritin with $H_2O_2$. When DNA was incubated with ferritin and $H_2O_2$, DNA strand breakage increased in a time-dependent manner. Hydroxyl radical scavengers strongly inhibited the ferritin/$H_2O_2$ system-induced DNA cleavage. We investigated the generation of hydroxyl radical in the reaction of ferritin with $H_2O_2$ using a chromogen, 2,2'-azinobis-(2-ethylbenzthiazoline-6-sulfonate) (ABTS), which reacted with ${\cdot}OH$ to form $ABTS^{+\cdot}$. The initial rate of $ABTS^{+\cdot}$ formation increased as a function of incubation time. These results suggest that DNA strand breakage is mediated in the reaction of ferritin with $H_2O_2$ via the generation of hydroxyl radicals. The iron-specific chelator, deferoxamine, also inhibited DNA cleavage. Spectrophotometric study using a color reagent showed that the release of iron from $H_2O_2$-treated ferritin increased in a time-dependent manner. Ferritin enhanced mutation of the lacZ' gene in the presence of $H_2O_2$ when measured as a loss of $\alpha$-complementation. These results indicate that ferritin/$H_2O_2$ system-mediated DNA cleavage and mutation may be attributable to hydroxyl radical generation via a Fenton-like reaction of free iron ions released from oxidatively damaged ferritin.

• Korean Chemical Engineering Research
• /
• v.45 no.3
• /
• pp.298-303
• /
• 2007

Several combinations of ozone based advanced oxidation processes were tested for the treatment of red water (RW) containing recalcitrant chemical pollutants produced from 2,4,6-trinitrotoluene (TNT) manufacturing process. $O_3$, $UV/O_3$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes were tested for the treatment of RW. The order of organic and color removal efficiency was found to be : $O_3{\leq}UV/O_3$ < $UV/O_3/H_2O_2$ < $UV/O_3/H_2O_2/Fe^{2+}$. The optimum conditions for the removal of organic and color in the $UV/O_3/H_2O_2/Fe^{2+}$ process were 0.053 g/min of ozone flow rate, 10 mM of $H_2O_2$ concentration and 0.1 mM of $FeSO_4$ concentration. Organic and color removal efficiencies were 96 and 100 % respectively in the $UV/O_3/H_2O_2/Fe^{2+}$ process. tert-butyl alcohol (t-buOH) was used as the hydroxyl radical scavenger. Enhancement of hydroxyl radical production was achieved by the combination of ozone with several oxidants such as UV, $H_2O_2$, $Fe^{2+}$.