• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.76-82
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• 2006

Fenton's reaction are difficult to apply in the field due to the low pH requirements for the reaction and the loss of reactivity caused by the precipitation of iron (II) at neutral pH. Moreover, Fenton-like reactions using iron mineral instead of injection of iron ion as a catalyst are operated to get high removal result at low pH. Because hydroxyl radical can generate at the surface of iron mineral, there are competition with a lot of hydroxide at around neutral pH. On the other side, to operate Fenton's reaction series at neutral pH, modified Fenton reaction is suggested. The complexes, composed by iron ions (ferrous ion or ferric ion)-chelating agent, could be acted as a catalyst and presented in the solution at neutral pH. However, modified Fenton reaction requires a lot of hydrogen peroxide. Accordingly, the purpose of this experiment was to effectively combine Fenton-like reaction and modified Fenton reaction for extending application of Fenton's reaction. i.e., injecting chelating agents in Fenton-like reaction at around neutral pH is increasing the concentration of dissolved iron ion and highly promoting the oxidation effect. 2,4,6-trinitrotoluene (TNT) was used as a probe compound for comparing reaction efficiencies in this study. If the concentration of dissolved iron ion in combined Fenton process were existed more than 0.1 mM, the total TNT removal were increased. Magnetite-NTA system showed the best TNT removal (76%) and Magnetite-EDTA system indicated about 56% of TNT removal. The results of these experiments proved more promoted 40-60% of TNT removal than Fenton-like reaction's.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.12
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• pp.1686-1692
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• 2012

The antioxidative activity of Kalopanax pictus shoots extracted using five different methods, stirrer extraction (SE), ultrasonification extraction (USE), vacuum extraction (VE), reflux extraction (RE), and reflux extraction after ultrasonification extraction (RUE), was evaluated to determine the most effective extraction method. RUE showed the highest yield of extract, and total polyphenol and flavonoid content. Additionally, the RUE extract showed higher antioxidative activity than that of the other extracts based on DPPH and ABTS free radical scavenging (90.85%, 99.83%), reducing power activity (OD 0.95, 700 nm), nitrite scavenging activity (55.46%), and ferrous ion chelating effect (45.12%).

• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.182-189
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• 2008

In this study, the effect of pH on the antioxidative activities of melanoidins formed as a result of the reaction between sugars, glucose (Glc) or fructose (Fru), and amino acids, L-asparagine (L-Asn) and D-asparagine (D-Asn) are examined. For this purpose, antioxidative activities were evaluated on the basis of reducing power, including ferric reducing/antioxidant power (FRAP) and free radical scavenging activity includes 1,1-diphenyl-2-picryl- hydrazil (DPPH) and 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS) and ferrous ion chelating activity. Ethylene diamine tetraacetate (EDTA) and trolox, a water-soluble analog of tocopherol, were used as reference antioxidant compounds. The antioxidative activities of the melanoidins at a pH of 7.0 were greater than those with a pHs of 4.0 and pH 10.0. Especially, it was found that the melanoidins formed from D-isomers are more effective antioxidants in different in vitro assays. The reducing power and chelating activity of the melanoidins formed from the Fru systems were higher than those of the melanoidins formed from the Glc systems. However, the ABTS radical scavenging activity of the melanoidins formed from the Glc systems were higher than those of the melanoidins formed from the Fru systems. In particular, the DPPH radical scavenging activity and the FRAP of the melanoidins showed different antioxidative activities according to pH level.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.440-447
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• 2004

Characteristics of human ${\beta}-carotene$ 15,15'-dioxygenase isolated by recombinant DNA technology was elucidated. Optimal pH and temperature were 9.0 and $40^{\circ}C$, respectively. Enzyme activity was temperature-sensitive. Enzyme was stable at pH 6.0-9.0 for 24 hr and under $5^{\circ}C$. Half-life of enzyme at $35^{\circ}C$ was 40 min. Crude preparations of enzyme were inhibited by ferrous ion-chelating agent and sulfhydryl-binding agent. GSH offsets inhibitory effect of PCMB. With increasing substrate concentrations, enzyme activity gave typical Michaelis-Menten curve, Based on Hanes-Woolf plot of data, $K_{m}\;and\;V_{max$ were $3.39{\times}10^{6}\;M\;and\;1.2\;pmol/mg$ protein/min, respectively.

• Journal of Soil and Groundwater Environment
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• v.25 no.1
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• pp.62-73
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• 2020

PAHs commonly found in industrial sites such as manufactured gas plants (MGP) are potentially toxic, mutagenic and carcinogenic, and thus require immediate remediation. In-situ chemical oxidation (ISCO) is known as a highly efficient technology for soil and groundwater remediation. Among the several types of oxidants utilized in ISCO, persulfate has gained significant attention in recent years. Peroxydisulfate ion (S₂O₈^2-) is a strong oxidant with very high redox potential (E⁰ = 2.01 V). When mixed with Fe²⁺, it is capable of forming the sulfate radical (SO₄^-·) that has an even higher redox potential (E⁰ = 2.6 V). In this study, the influence of various iron activators on the persulfate oxidation of PAHs in contaminated soils was investigated. Several iron sources such as ferrous sulfate (FeSO₄), ferrous sulfide (FeS) and zero-valent iron (Fe(0)) were tested as a persulfate activator. Acenaphthene (ANE), dibenzofuran (DBF) and fluorene (FLE) were selected as model compounds because they were the dominant PAHs found in the field-contaminated soil collected from a MGP site. Oxidation kinetics of these PAHs in an artificially contaminated soil and the PAH-contaminated field soil were investigated. For all soils, Fe(0) was the most effective iron activator. The maximum PAHs removal rate in Fe(0)-mediated reactions was 92.7% for ANE, 83.0% for FLE, and 59.3% for DBF in the artificially contaminated soil, while the removal rate of total PAHs was 72.7% in the field-contaminated soil. To promote the iron activator effect, the effects of hydroxylamine as a reducing agent on reduction of Fe³⁺ to Fe²⁺, and EDTA and pyrophosphate as chelating agents on iron stabilization in persulfate oxidation were also investigated. As hydroxylamine and chelating agents (EDTA, pyrophosphate) dosage increased, the individual PAH removal rate in the artificially contaminated soil and the total PAHs removal rate in the field-contaminated soil increased.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.2
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• pp.250-256
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• 2013

We investigated noodles supplemented with turmeric, purple sweet potato, or seaweed (Hizikia fusiforme) for their functional properties, including total phenol, flavonoid contents, electron donating abilities, and nitrite scavenging abilities. The percentage of total phenolic compounds in turmeric, purple sweet potato, and seaweed noodles were 2.40, 2.47, and 1.27%, respectively, whereas the percentage of total flavonoid contents were 0.55, 0.92, 0.74%, respectively. Results showed that purple sweet potato noodles had the highest amount of phenolic compounds and flavonoids compared to the other types of noodles. The electron donating abilities of the turmeric, purple sweet potato, and seaweed noodles were 4.72, 4.11, and 3.11 at 1,000 ppm respectively. The nitrite scavenging abilities of the turmeric, purple sweet potato, and seaweed noodles were 75.93, 79.81, and 73.51% at pH 1.2, respectively. Purple sweet potato noodles had the highest nitrite scavenging abilities, with an effect better than BHT and ascorbic acid. The ferrous ion chelating effect of turmeric, purple sweet potato, and seaweed noodles were 12.17, 13.63, and 42.12%. All of the experimental results showed good anti-oxidative activity; thus rice noodles supplemented with turmeric, purple sweet potato, or seaweed, have good functional effects for human beings.

• Mycobiology
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• v.39 no.1
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• pp.12-19
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• 2011

Cellular damage caused by reactive oxygen species has been implicated in several diseases, thus establishing a significant role for antioxidants in maintaining human health. Acetone, methanol, and hot water extracts of Pleurotus citrinopileatus were evaluated for their antioxidant activities against ${\beta}$-carotene-linoleic acid and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, reducing power, ferrous ion-chelating abilities, and xanthine oxidase inhibitory activities. In addition, the tyrosinase inhibitory effects and phenolic compound contents of the extracts were also analyzed. Methanol and acetone extracts of P. citrinopileatus showed stronger inhibition of ${\beta}$-carotene-linoleic acid compared to the hot water extract. Methanol extract (8 mg/mL) showed a significantly high reducing power of 2.92 compared to the other extracts. The hot water extract was more effective than the acetone and methanole extracts for scavenging DPPH radicals. The strongest chelating effect (92.72%) was obtained with 1.0 mg/mL of acetone extract. High performance liquid chromatography analysis detected eight phenolic compounds, including gallic acid, protocatechuic acid, chlorogenic acid, ferulic acid, naringenin, hesperetin, formononetin, and biochanin-A, in an acetonitrile and hydrochloric acid (5 : 1) solvent extract. Xanthine oxidase and tyrosinase inhibitory activities of the acetone, methanol, and hot water extracts increased with increasing concentration. This study suggests that fruiting bodies of P. citrinopileatus can potentially be used as a readily accessible source of natural antioxidants.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.241-244
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• 2017

The antioxidant activity of various solvent extracts from Jeju camellia mistletoe (Korthalsella japonica (Thunb.) Engl.) was investigated using various in vitro assays as the 1,1-diphenyl-2-picrylhydrazyl radical scavenging, ferrous ion chelating and reducing power assays. Methanol and ethanol extracts showed the most potent antioxidant activity in all assays tested followed by water extract. The inhibitory effect of the Jeju camellia mistletoe extracts on pancreatic lipase and $\acute{a}$-glucosidase was also evaluated and the results showed that methanol and ethanol extracts markedly reduced both enzyme activities. Therefore, the methanol and ethanol extracts of Jeju camellia mistletoe is definitely worthy of further investigation for these beneficial effects on nutraceutical medicine.

• Preventive Nutrition and Food Science
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• v.17 no.2
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• pp.116-121
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• 2012

Water extract from Pinus densiflora (WPD) was investigated for its antioxidant activity and its ability to provide protection from DNA damage. A series of antioxidant assays, including a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging assay, a reducing power assay, a metal-chelating assay, a superoxide radical scavenging assay, and a nitrite scavenging ability, as well as a DNA damage protection assay were performed. Total phenolic content was found to be 211.32 mg Tan/g WPD. The extract scavenged 50% DPPH free radical at a concentration of 21.35 ${\mu}g/mL$. At that same concentration, the reducing power ability of WPD was higher than that of ${\alpha}$-tocopherol. The extract chelated 68.9% ferrous ion at the concentration of 4 mg/mL. WPD showed better nitrite scavenging effect at the lower pH. Meanwhile, WPD exhibited a strong capability for DNA damage protection at 1 mg/mL concentration. Taken together, these data suggest water extract from Pinus densiflora could be used as a suitable natural antioxidant.

• Korean Journal of Plant Resources
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• v.24 no.2
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• pp.253-259
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• 2011

In this studies, contents and activities of antioxidative substances in the fruits of a pear cultivar and five Korean wild pear lines were investigated. The content of total phenolic compounds was highest with Pyrus pyrifolia var. culta "Shingo" (7.68 $mg{\cdot}g^{-1}$, D.W.) while total flavonoids was highest with P. ussuriensis var. acidula (5.66 $mg{\cdot}g^{-1}$, D.W.). The contents of total polyphenols and flavonoids varied according to plant species, but in general pyrifolia lines had higher total polyphenols than total flavonoids whereas in ussuriensis lines total flavonoid contents were higher than total polyphenols. The scavenging effects of DDPH radicals was highest with highest with P. ussuriensis var. seoulensis ($RC_{50}$=1.45 $mg{\cdot}mL^{-1}$) and that of ABTS radicals was highest with P. ussuriensis var. acidula ($RC_{50}$=0.69 $mg{\cdot}mL^{-1}$). A pear cultivar "Shingo" showed highest total polyphenol content, but scavenging activity of DDPH and ABTS radicals was lowest. The fruits of P. ussuriensis var. seoulensis contained low level of phenolic compounds, but their scavenging effects on two radicals was superior. Ferrous ion chelating effect was high in P. pyrifolia var. culta (98.93%), and in P. ussuriensis var. sinensis (68.71%), but two species had low scavenging activity. The content of phenolic compounds in wild pears was not always directly proportional to the radical scavenging activity. Neither radical scavenging activity was to ferrous ion chelating activity. In conclusion the fruits of P. ussuriensis var. acidula, P. ussuriensis var. seoulensis, and P. ussuriensis var. sinensis had great potential for the development of new antioxidative functional food because their antioxidative activity is higher or at least similar to P. pyrifolia var. culta. However, due to their different levels of antioxidative effects, the development of methods of using them jointly, not singly, to obtain maximum level of antioxidants is recommended.