• BMB Reports
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• v.32 no.6
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• pp.585-593
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• 1999

The water and methanol extracts of Artemisia argyi showed significant cytotoxicities against J774A.1 cells but not so much against normal leukocytes. The cytotoxicities were found to be dependent on the extract concentration and the incubation time. The concentration of water and methanol extracts inhibiting 50% of cell proliferation ($IC_{50}$) were estimated to be 44.2 mg/ml and 71.6 mg/ml, respectively. In the presence of Artemisia argyi water extract, total superoxide dismutase (CuZnSOD and MnSOD) activities of media, cytoplasmic and mitochondrial fractions of J774A.1 cells increased in accordance with cytotoxicity. MnSOD was found to be the main component of enhanced total SOD activities, particulary in the mitochondrial fraction. In contrast to SOD, catalase and glutathione peroxidase (GPx) were not found in any instance of the current investigation. In addition, substantial amount of $O_2^-$ appeared to be generated in the mitochondrial fraction under the influence of Artemisia argyi. All data put together, it is postulated that Artemisia argyi extracts seem to stimulate $O_2^-$ generation in mitochondria of J774A.1 cells with concomitant increases of SODs. Since $H_2O_2$, the reaction product of SOD on $O_2^-$, is known to be readily converted to very toxic $OH{\cdot}$ in the absence of catalase and/or GPx cooperation, toxicity derived from ROS such as $O_2^-$, $H_2O_2$, and $OH{\cdot}$ may be the main cause of necrosis and/or apoptosis of J774A.1 cells.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1060-1064
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• 1995

The reactivity of superoxide ion (O2-.) with halogenated substrates is investigated by cyclic voltammetry and rotated ring-disk electrode method in aprotic solvents. The more positive the reduction potential of the substituted nitrile, the more facile is nucleophilic displacement by O2-.. The reaction rates of halogenonitriles with O2-. vary according to the leaving-group propensity of halide (Br > Cl > F). The relative reaction rates of other substituted nitriles are in the order of electron-withdrawing propensity of the substituent group (CN > C(O)NH2 > Ph ≒ CH2CN). The reaction of O2-. with dihalocarbons indicates that five-membered rings can be rapidly formed by the cyclization of substrate and O2-., and the relative rates of cyclization depend on the number of methylenic carbons {Br(CH2)nBr, [n=1 < 2 < 3 > 4 > 5]}. Mechanisms are proposed for the reaction of O2-. with halogenated substrates.

• Applied Biological Chemistry
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• v.36 no.5
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• pp.364-369
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• 1993

Triton X-100 enhances to a marked extent the analytical sensitivity of the nitrobluetetrazolium (NBT) reduction method for the assay of superoxide$(O^-_{\.{^.2}})$ production. In the present work, it was attempted to elucidate the physicochemical nature of this Triton X-100 effect, focusing on not only the surfactant-caused stabilization of the water-insoluble formazan colloid but also the kinetic competition between the $NBT-O^-_{\.{^.2}}$ reaction and the autodisproportionation of concommitantly occuring in aqueous media. The measurements of formazan and $H_2O_2$ formed in a number of reaction systems, as prepared by vortex-mixing potassium superoxide dissolved in an aprotic solvent with aqueous solutions of NBT, revealed that Triton X-100 exerts its effect both through preventing formazan colloid from aggregation and thereby increasing the formazan absorbance and through suppressing the autodisproportionation reaction of $O^-_{\.{^.2}}$. It also turned out that the relative shares of the colloid stabilization effect and the kinetic effect in the contribution to the sensitivity amplification of the NBT method are dependent upon the reaction conditions, particulary the molar concentration ratio of NBT to $O^-_{\.{^.2}}$ in the reaction systems.

• Molecules and Cells
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• v.45 no.4
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• pp.193-201
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• 2022

Excessive production of reactive oxygen species (ROS) is a key phenomenon in tumor necrosis factor (TNF)-α-induced cell death. However, the role of ROS in necroptosis remains mostly elusive. In this study, we show that TNF-α induces the mitochondrial accumulation of superoxide anions, not H₂O₂, in cancer cells undergoing necroptosis. TNF-α-induced mitochondrial superoxide anions production is strictly RIP3 expression-dependent. Unexpectedly, TNF-α stimulates NADPH oxidase (NOX), not mitochondrial energy metabolism, to activate superoxide production in the RIP3-positive cancer cells. In parallel, mitochondrial superoxide-metabolizing enzymes, such as manganese-superoxide dismutase (SOD2) and peroxiredoxin III, are not involved in the superoxide accumulation. Mitochondrial-targeted superoxide scavengers and a NOX inhibitor eliminate the accumulated superoxide without affecting TNF-α-induced necroptosis. Therefore, our study provides the first evidence that mitochondrial superoxide accumulation is a consequence of necroptosis.

• YAKHAK HOEJI
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• v.52 no.6
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• pp.441-445
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• 2008

To investigate effect of caffeic acid on the intracellular reactive oxygen species production, we used DHE for intracellular superoxide anion production, DCF for intracellular ${H_2}{O_2}$ production and DHR for intracellular hydroperoxide production in Raw 264.7 cells. DPPH assay showed that antioxidant activity of caffeic acid with 39.5 ${\mu}M$ of ${IC}_{50}$ values was similar to that of ascorbic acid with 41.3 ${\mu}M$ of ${IC}_{50}$ values. Caffeic acid dose-dependently inhibited silica-induced ${H_2}{O_2}$ and hydroperoxide production but did not affect superoxide anion production in Raw 264.7 cells, which suggest that antioxidant effect of caffeic acid acts on the post-step of superoxide anion. On the other hand, caffeic acid showed a potent antioxidant effect in $lCuSO_4$-induced lipid peroxidation. Furthermore, plasma superoxide dismutase activity (3.43${\pm}$0.23 U/ml) in 10 mg/kg caffeic acid-fed mice was significantly higher than that (2.32${\pm}$0.24 U/ml) of control. From the above results, it is referred that caffeic acid appears to have potent anti-oxidant activity in both cell system and in vivo system.

• Journal of Life Science
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• v.12 no.2
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• pp.75-79
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• 2002

Tea catechins, the most important compounds in tea polyphenols, can efficiently scavenge superoxide anion free-radical ($O_2$.), hydroxyl radical. (.OH) The mechanism of scavenging active oxygen free radicals was investigated by ESR spin trapping technique and Chemiluminescence. Results showed that various tea catechins constitute an antioxidant cycle in accordance with the decreasing order of the first reductive potential, and produce the effect of cooperative strength each other. Esterificated catechins could scavenge active oxygen free radicals more effectively than the non-esterificated ones. When.OH and $O_2$.- were scavenged by (-)-epigallocatechin gallate [(-)- EGCG], the stoichiometric factors were 6, and the rate constants of scavenging reaction reached $7.71{\times}10^6$ and $3.52{\times}10^{11}$ L $mmol^{-1}s^{-1}$, respectively. In the mean time, tea catechins could scavenge superoxide anion fiee radical ($O_2$-.) and hydroxyl radical (.OH) in a dose dependent manner. But at higher concentration or pH value, tea catechins can induce the prooxidant.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.10a
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• pp.66-70
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• 2003

The first line of antioxidant defense against reactive oxygen species includes the enzymatic activity of the superoxide dismutase (SOD) that catalyzes the disproportionation of superoxide to hydrogen peroxide and water. The SOD mainly removes highly toxic $O_2$$^{[-10]}$ and also prevents $O_2$$^{[-10]}$ mediated reduction of iron and subsequent OH$^{[-10]}$ generation. Along with an interest in SOD as a first line of defense against damage mediated by the superoxide anion, the SOD1 enzyme has been subjected to investigation in the molecular and cellular level. (omitted)

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.345-353
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• 1995

${\beta}-Carboline$ alkaloids including harmaline have been shown to inhibit enzymatically or nonenzymatically induced-lipid peroxidation of microsomes. This study was done to explore the antioxidant ability of harmaline and harmalol on the oxidative injuries of hyaluronic acid, lipid and collagen by $Fe^{2+}$ and $H_2O_2$. Their scavenging actions on reactive oxygen species were also examined. Harmaline, harmalol, superoxide dismutase, catalase and DMSO inhibited both degradation of hyaluronic acid by $Fe^{2+}$ and $H_2O_2$ and lipid peroxidation of microsomes by $Fe^{2+}$. In these reactions, DABCO inhibited degradation of hyaluronic acid but did not affect lipid peroxidation. ${\beta}-Carbolines$ inhibited degradation of cartilage collagen by $Fe^{2+}$, $H_2O_2$ and ascorbic acid. The reduction of ferricytochrome c due to autoxidation of $Fe^{2+}$, which is inhibited by superoxide dismutase, was not affected by harmaline and harmalol. They also did not have a decomposing action on $H_2O_2$. Hydroxyl radical production in the presence of $Fe^{2+}$ and $H_2O_2$ was inhibited by harmaline, harmalol and DMSO. Harmaline and harmalol may inhibit the oxidative injuries of hyaluronic acid, lipid and cartilage collagen by $Fe^{2+}$ and $H_2O_2$ through their scavenging actions on reactive oxygen species, OH and probably iron-oxygen complexes and exert antioxidant abilities.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.135-142
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• 1984

New type dioxygen bridged complexes of palladium were prepared by using $KO_2$ as a source of superoxide ion $(O_2^-)$. The method is completely different from the traditional one which has adopted the oxidative addition of molecular oxygen to transition metal complexes in low valency. It was suggested that the reaction to prepare the dioxygen complexes proceeded via nucleophilic displacement followed by electron transfer reaction. Five new type dioxygen complexes having ${\pi}$-allyl ligand were prepared and characterized by the application of the reaction of $O_2^-$.

• Microbiology and Biotechnology Letters
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• v.28 no.1
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• pp.1-7
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• 2000

The bacterial strain JW-2 which conferred resistance against paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) was isolated from soil. The strain was identified as an Ochrobactrum anthropi based on its morphological, physiological, biological and fatty acid composition, and was designated as Ochrobactrum anthropi JW-2. We compard paraquat resistance of O. anthropi JW-2 with Escherichia coli J105. In the presence of 100mM paraquat, E. coli JM105 was not grown whereas the growth rate of O. anthropi was about 70% of control. We compared the sensitivity of O. anthropi JW-2 and E. coli J105 to redox-cycling compounds such as paraquat, plumbagin or menadione, which are known to exacebate wuperoxide generation. O. anthropi JW-2 did not show cross-resistance to plumbagin or menadione. superoxide dismutase activity was increased in paraqunt-treated E. coli JM105 while it was not increased in O.anthropi JW-2. These results suggest that the mechanism of paraquat resistance in O.anthropi JW-2 is probably due to selectively decreased permeability toward paraquat by membrane protein.