• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.668-672
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• 2003

An antioxidative activity of Portulaca oleracea was tested by in vitro experimental models. The antioxidative activities were determined by evaluation the DPPH radical scavenging activity and by measuring lipid peroxide using 2-thiobarbituric acid (TBA). The crude extract was sequentially partitioned with n-hexane, 15% aq. MeOH, EtOAc, n-BuOH, $H_2O$. Among them, a remarkable antioxidative effect was observed in the fractions of EtOAc and n-BuOH. The DPPH radical scavenging effect $(IC_{50}=17.90{\mu}g/ml)$ of the n-BuOH soluble fraction was comparable with that of natural antioxidant, ${\alpha}-tocopherol(IC_{50}=\;6.99{\mu}g/ml)$ and the inhibitory effect of lipid peroxidation in mouse liver homogenate was similar to that of natural antioxidant, L-ascorbic acid at a concentration of 0.1mg/ml to 5mg/ml. From the BuOH soluble fraction yielded two biophenolic glycosides, 3-hydroxy-1-(2-hydroxyethyl)phenyl-4-O-${\beta}$-D-glucopyranoside(1) and 2-(3,4-dihydroxyphenyl)ethyl-O-${\beta}$-D-glucopyranoside(2) using column chromatography and revered-phase HPLC. In particular, the DPPH radical scavenging activity of 2 was comparable to that tocopherol$(IC_{50}=6.59{\mu}g/ml)$.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.115-123
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• 2003

Simultaneous measurements of velocity and OH distribution were made using particle image velocimetry(PIV) and planar laser-induced fluorescence(PLIF) of OH radical in turbulent hydrogen nonpremixed flames with coaxial air. The OH radical was used as an approximate indicator of chemical reaction zone. The OH layer was correlated well with the stoichiometric velocity, $U_s$, instantaneously and on average. In addition, high strain-rate regions almost coincide with the OH distribution. The residence time in flame surface, calculated from the root-mean-square value of the radial velocity, is proportional to $(x/d_F)^{0.7}$. It is found that the mean value of principal strain rate on the OH layer can be scaled with $(x/d_F)^{-0.7}$ and therefore, the product of the residence time and the mean strain rate remains constant over all axial positions.

• Journal of Life Science
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• v.27 no.10
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• pp.1121-1129
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• 2017

The authors evaluated the scavenging activities of ABTS+ radical, hydroxy radical (OH), nitric oxide (NO), and ferric ion reducing antioxidant power (FRAP) from ethanol extracts of four edible alga, Enteromorpha linza, Porphyra tenera, Sargassum fusiforme, and Undaria pinnatifida. ABTS+ scavenging activity was analyzed according to the method of Brand-Williams et al. ABTS+ scavenging activity of S. fusiforme was evaluated to 61.8% at 8.0 mg/ml. ABTS+ scavenging activity of P. tenera was evaluated to 35.7% at 8.0 mg/ml. P. tenera and U. pinnatifida showed similar inhibitions of ABTS+ scavenging activity. According to the results of the OH assay in seaweed, inhibitory activities were in the order of S. fusiforme > P. tenera > U. pinnatifida > E. linza. The results showed scavenging activity for NO in the following order of potency: S. fusiforme > P. tenera > U. pinnatifida > E. linza with concentration values of 8.0 mg/ml. The NO scavenging activities of dough, which was instant noodles mixed with S. fusiforme and 3.5% salt, were 27.2% at 8.0 mg/ml. After boiling for 5 minutes, FRAP scavenging activity of instant noodles mixed with extracts of U. pinnatifida was evaluated to 31.5% at 8.0 mg/ml. S. fusiforme showed the highest inhibition activity of ABTS+, OH, NO, and FRAP among the four algae. Thus, these findings provide evidence that P. tenera, U. Pinnatifida, S. fusiforme, and E. linza extracts could become sources of natural antioxidants.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.27-38
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• 1999

We constructed a wire-cylinder type pulsed corona discharge system for $NO_x$ removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch. $N_2$ spectrum($c^3{\Pi}_u{\rightarrow}X^1{\Sigma}_g{^+}$) was measured in the range of 300 - 450 nm and oxidizing OH radical emission($A^2{\Sigma}^+{\rightarrow}X^2{\Pi}$) was measured in case $N_2$ was supplied with water bubbling. As wet gas composition of inlet $N_2$ supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of $C_2H_4,\;H_2O,\;H_2O_2$ on the intensity of OR emission and $NO/NO_2/NO_x$ reduction and analysed the related reaction mechanism in corona discharge process. $H_2O_2$ additive increased the intensity of OH emission and $NO/NO_x$ reduction.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.851-855
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• 2006

The aim of this study was to investigate characteristics of formation of mixed oxidants and some aspects of the performance of electrochemical process as an alternative disinfection strategy for water purification. The study of electrochemical process has shown free chlorine to be produced, but smaller amounts of stronger oxidants, such as ozone, hydrogen peroxide and OH radicals, were also generated. The formation of ozone and hydrogen peroxide increased with increasing electric conductivity, but was limited at conductivities greater than 0.6 mS/cm. Also, formation of OH radical was enhanced as electric conductivity was increased to 0.9 mS/cm and The stead-state concentrations of OH radical were calculated at $1.1{\sim}6.4{\times}10^{-14}M$. Using E. coti, inactivation kinetic studies were performed. With the exception of free chlorine, the role of mixed oxidants, especially OH radical, was investigated for enhancement of the inactivation rate.

• The Korea Journal of Herbology
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• v.27 no.3
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• pp.23-29
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• 2012

Objective : Sanguisorbae Radix(SO). that belong to Rosaceae is widely distributed in Asia including Korea, Japan and China. It has been used as traditional medicine from old times as a treatment for anti-inflammatory drugs. This study was designed to investigate the effects of n-BuOH fractions of SO on anti-oxidant effect and anti-microbial effect on $Streptococcus$ $mutans$ ($S.$ $mutans$). Methods : The anti-microbial effect of $n$-BuOH fractions of SO. was assessed by the paper disk diffusion method and anti-oxidant effect was assessed by the DPPH radical scavenging effect, Superoxide anion radical scavenging effect and SOD like ability. Results : DPPH radical scavenging of the $n$-BuOH fraction from SO in 50 ug/mL was shown to be Fr-2 (89.9%), Fr-3 (88.7%), Fr-4 (76.3%), Fr-1 (59.4%), Fr-5 (56.2%). Superoxside anion radical scavenging activity of the n-BuOH fraction from SO. in 50 ug/mL for Fr-3 was shown to be 78%. SOD-like activity of n-BuOH fraction from the SO in 1000 ug/mL for Fr-3 were shown to be 76.1% respectively. The $n$-BuOH fraction from the SO had high anti-microbial effect on $S.$ $mutans$. Conclusion : As a result, the $n$-BuOH fraction from SO. has good anti-microbial and anti-oxidant effects in a concentration-dependent manner.

• Journal of Applied Biological Chemistry
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• v.50 no.3
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• pp.115-119
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• 2007

To discover the sources with antioxidant and tyrosinase inhibitory activities in Korean traditional medicines, 10 extract of medicinal plants were screened for their potential to scavenge stable 1,1-diphenyl-2-picryhydrazyl (DPPH) free radical, inhibit hydroxyl radical (${\cdot}OH$), total phenolic content, and inhibition of tyrosinase. The potency of DPPH radical scavenging activity was shown in the extract of Ulmus davidiana var. japonica Nakai that has a greater effect with $IC_{50}$ values of $6.49{\pm}5.43{\mu}g/mL$, than BHA ($IC_{50}=20.99{\pm}0.74{\mu}g/mL$), L-ascorbic acid $(IC_{50}=20.59{\pm}1.06{\mu}g/mL),\;and\;{\alpha}-tocopherol\;(IC_{50}=25.55{\pm}0.26{\mu}g/mL)$ as a positive control. The ${\cdot}OH$ scavenging activities were observed in the plants tested. Acanthopanax senticosus, Cirsium setiders, U. davidiana exhibited scavenging activity of more than 60% at $500{\mu}g/mL$. The scavenging activity(%) of BHA and a-tocopherol were 64.32 and 55.87% at $500{\mu}g/mL$, respectively. The total phenolic content was determined, in order to assess its effect on the extract's antioxidant activity. The total phenoic content of $33.37{\pm}0.52mg/g$ was conformed by methanolic extract of U. davidiana. The U. davidiana and Morus bombycis exhibited tyrosinase inhibitory activity with a $34.28{\pm}1.32\;and\;75.57{\pm}1.10%$, respectively. In particular, M. bombycis has stronger tyrosinase inhibitory activity than albutin with $36.48{\pm}3.56%$ as a positive control. This work showed that the inhibitory abilities of Korean medicinal plants, such as U. davidiana and M. bombycis, on DPPH free radical, inhibit hydroxyl radical (${\cdot}OH$), and inhibition of tyrosinase and total phenolic content, can be useful in the prevention and treatment of free radical-relate disease. Investigations into further isolation of inhibitory principles of U. davidiana and M. bombycis are now in progress.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.761-767
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• 2018

Degenerative diseases are commonly associated with excess free radicals. Acer okamotoanum, a plant endemic to Korea, is reported to have anti-oxidant, anti-cancer, and anti-viral activities. We previously isolated flavonoids from the ethyl acetate fraction of A. okamotoanum such as quercitrin (QU), isoquercitrin (IQ), and afzelin (AF). In the present study, the in vitro antioxidant activity of flavonoids such as QU, IQ, and AF isolated from the ethyl acetate fraction of A. okamotoanum were investigated by measuring the free radical scavenging activity including 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical ($^{\cdot}OH$), and superoxide anion ($O_2{^-}$). The flavonoids (QU, IQ, and AF) concentration-dependently showed a DPPH radical scavenging activity. In particular, QU and IQ showed a higher DPPH radical scavenging activity than that of AF. In addition, the flavonoids (QU, IQ, and AF) at $10{\mu}g/mL$ showed over an 80% scavenging effect against $^{\cdot}OH$ radical production. Furthermore, the $O_2{^-}$ radical scavenging activity of the flavonoids, QU, IQ, and AF increased in a dose-dependent manner. Particularly, IQ exerted the strongest scavenging activities against $^{\cdot}OH$ and $O_2{^-}$ radicals among the other flavonoids. These results indicate that the flavonoids from A. okamotoanum, in particular IQ, would have a protective activity against oxidative stress induced by free radicals, and potentially be considered as a natural antioxidant agent.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.145-148
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• 2000

• Korean Journal of Pharmacognosy
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• v.34 no.4 s.135
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• pp.324-326
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• 2003

The methanol (MeOH) extract and ist fractions of Taraxacum mongolicum (Compositae) were examined for their scavenging effects on 1,1-diphenyl-2- phenylhydrazyl (DPPH) and superoxide radicals, and hepatoprotective effects on tacrine-induced cytotoxicity in human hepatoma cell line, Hep G2 cells. Both methylene chloride $(CH_2Cl_2)$ and butanol (n-BuOH) soluble fractions of the MeOH extract showed the free radicals scavenging and hepatoprotective effects. From these results, it is suggested that hepatoprotective effect of these fractions partly relies on their free radical scavenging activity.