• Journal of Korean Society on Water Environment
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• v.32 no.5
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• pp.403-409
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• 2016

In this study, a TiO₂ nanotube was grown on a titanium plate by using anodic oxidation method for the evaluation of TiO₂ nanotube morphology. The TiO₂ nanotube was grown in an electrolyte containing ethylene glycol, 0.2 wt% of NH₄F and 2 vol% of H₂O. Applied voltage varied from 30 to 70 V and the morphology of the TiO₂ nanotube was observed. After anodization, a TiO₂ nanotube plate was immersed in 35℃ ethanol for 24 hours. Anatase and rutile crystal forms of TiO₂ nanoutbe were observed after annealing. 4-chrolobenzoic acid, a probe compound for OH radicals, was dissolved in H₂O in order to measure the OH radical. Liquid chromatography was used to check the concentration of the 4-chrolobenzoic acid. The OH radical generation by TiO₂ nanotube plate was proportionate to the length of the TiO₂ nanotube. Furthermore, when the number of TiO₂ nanotube plate increased, the OH radical generation increased as well.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.1
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• pp.64-69
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• 2004

The deficiency of the neurotransmitter acetylcholine(ACh) is responsible for the initiation of Alzheimer's disease. In addition, there is a simple evidence that oxidative stress significantly increases in persons with Parkinson's disease compared to age-matched healthy persons. Therefore, the objective of the study was to investigate the neurodegeneration inhibitory effect of soybean(Glycine Max) and Yak-Kong(Rhynchosia Nolubilis) by measuring the degree of inhibiting Acetylcholinesterase (AChE) catabolizing the ACh and the free radical scavenger effect in vitro. AChE was measured by the minor modified Ellman assay. Free radical scavenging activity was measured using l-diphenyl-2-picrylhydrazyl (DPPH). First, the MeOH extracts of Soybean and Yak-Kong showed the AChE inhibiting activity of 62.0$\pm$2.43％ and 65.0$\pm$3.29％ at the 5 mg/$m\ell$ concentration. The 50％ inhibitory concentration ($IC_{50}$/) of AChE was 1.96 and 1.31 mg/$m\ell$ in the MeOH extracts of soybean and Yak-Kong. Second, the MeOH extracts of soybean and Yak-Kong showed the free radical scavenger activity of 23.1$\pm$4.26％ and 80.7$\pm$4.61％ at the 5 mg/$m\ell$. IC50 of free radical scavenger activity in Soybean and Yak-Kong was 13.00 and 1.41 mg/$m\ell$ in MeOH extracts and was 5.95 and 2.74 mg/$m\ell$ in hot-water extracts, respectively. In this study, the extracts of Soybean and Yak-Kong showed powerful effects in the AChE inhibition and free radical scavenging. The extracts of Soybean and Yak-Kong were expected to prevent the many neurodegenerative diseases.

• Preventive Nutrition and Food Science
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• v.16 no.3
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• pp.224-229
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• 2011

The radical scavenging activity and inhibition effect from lipid peroxidation induced by peroxyl radical of methanol extract from Perilla frutescens and its active compound, rosmarinic acid (RA), were investigated in vitro. The treatment of extract and RA scavenged 1,1-diphenyl-2-picrylhydrazyl, hydroxyl radical (${\cdot}OH$) and nitric oxide in a concentration-dependent manner. In particular, the extract and RA showed strong radical scavenging activity against ${\cdot}OH$, the most toxic and reactive radical. In addition, Perilla frutescens and RA effectively inhibited lipid oxidation induced by sodium nitroprusside and 2,2'-azobis(2-aminopropane) dihydrochloride, determined by the ferric thiocyanate method. The present results suggest that Perilla frutescens and RA play a protective role against oxidative stress induced by free radical and lipid peroxidation.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E3
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• pp.129-136
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• 2003

Effects of inorganic aerosols on the kinetics of the hydroxyl radical reactions with selected aliphatic alkanes have been investigated using the relative rate technique. The relative rates in the absence and presence of aerosols were determined for n-butane, n-pentane, n-hexane, n-octane, and n-decane. P-xylene was used as a reference compound. Inorganic aerosols including (NH$_4$)$_2$SO$_4$, NH$_4$NO$_3$, and NaCl aerosols at two different aerosol concentrations that are typical of polluted urban conditions were tested. Total surface areas of aerosols were 1400 (Condition I) and 3400 $\mu$$m^2$ cm$^{-3}$ (Condition II). Significant changes in the relative rates in the presence of the inorganic aerosols were not observed for the n-butanel/$.$OH, n-pentanel/$.$OH, n-hexanel/$.$OH, n-octanel/$.$OH, and n-decanel/$.$OH reactions versus p-xylenel/$.$OH reaction. These results suggest that the promoting effects depend on the semiconducting property of the aerosols and the nature of the organic compounds.

• The Korean Journal of Pharmacology
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• v.21 no.1
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• pp.34-48
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• 1985

In vitro effects of nitrofurantoin, an antimicrobial agent for acute and chronic urinary tract infection, on the lung microsomal lipid peroxidation and the generation of reactive oxygen radicals were investigated to elucidate the biochemical mechanisms of its in vivopulmonary toxicity. The interaction of nitrofurantoin with porcine lung microsome resulted in significant lipid peroxidation. In addition, nitrofurantoin stimulated the generation of reactive oxygen radicals, $O^{-}_{2}{\cdot},\;H_2O_2$ as well as a highly reactive secondary oxygen species, $OH{\cdot}$. The stimulation of lipid peroxidation was inhibited not only by superoxide dismutase and catalase, but also by hydroxyl radical scavengers, mannitol and thiourea. Neither singlet oxygen $({^1}O_{2})$ was detected during the incubation of microsome with nitrofurantoin, nor lipid peroxidation was inhibited by singlet oxygen scavengers. When incubated anaerobically under the nitrogen atmosphere, the ability of nitrofurantoin to stimulatle lipid peroxidation was abolished. It appears that NADPH-dependent metaboliam of nitrofurantoin in pulmonary microsome under aerobic condition is accompanied by the stimulation of lipid peroxidation through the mediation of reactive oxygen radicals, particularly hydroxyl radical. It is strongly suggested from these results that the stimulation of pulmonary microsomal lipid peroxidation by the reactive oxygen radical may be a in vivo mechanism of pulmonary toxicity caused by nitrofurantoin.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.527-538
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• 2023

The aim of this study was to investigate the antioxidant effects of O. robusta stem extract (ORE) and to determine the total polyphenol and flavonoid contents. Free radical scavenging properties were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)), and ·OH (hydroxyl radical) scavenging assays. Total polyphenol and flavonoid contents were measured using Folin-Ciocalteu reagent and aluminum chloride colorimetric methods, respectively. Active compounds of ORE were determined using high-performance liquid chromatography (HPLC). The results of the study showed that ORE exhibited DPPH, ABTS, and ·OH radical scavenging activities in a dose-dependent manner. Especially, 1,000 ㎍/mL of ORE showed the strongest radical scavenging properties against DPPH, ABTS, and ·OH. ORE contained total polyphenol content of 57.4 mg GAE/g and total flavonoid content of 5.4 mg QE/g, which may contribute to their antioxidant effects. As a result of HPLC, the contents of active compounds in ORE, dihydrokaempferol (0.65 ㎍/mL), and 3-O-methylquercetin (1.10 ㎍/mL) were confirmed. In conclusion, ORE may be useful as a functional material with antioxidant properties.

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.237-243
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• 1995

The measurments of neutral semiquinone radicals, which were formed from the laser flash photolysis of anthraquinone (AQ) in the mixed solvents were carried out by the time resolved electron spin resonance (trESR) spectroscopy. The chemically induced dynamic electron polarization (CIDEP) spectra of the neutral semiquinone radical (AQH${\cdot}$) and semiquinone radical anion (AQ${\cdot}$-) were successively detected in the laser flash photolysis of AQ in the mixtures of 2-propanol (PrOH) and triethylamine (TEA). The neutral semiquinone radical was short-lived with the half-life of 0.8 ${\mu}sec$, whereas the semiquinone radical anion was relatively stable and then its cwESR could be observed. The rate constant of the spin-depolarization of semiquinone radical anion was $2.6{\times}10^5 sec^{-1}$ and the decay of the radical anion was the first order reaction with the rate constant of $3.0{\times}10^2\; sec^{-1}$. No CIDEP of semiquinone radical anion was observed in the mixture of PrOH and the lower concentration of TEA than 2 percent. The CIDEP spectrum of the neutral semiquinone radical was detected in the mixture of benzene and TEA with the half-life of 3.0 ${\mu}sec$. The neutral semiquinone radical could not be detected by cwESR. Neither CIDEP nor ESR absorption could be observed in PrOH, TEA or benzene only.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1393-1402
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• 1997

Characteristics of the lifted flame which is generated by issuing of the fuel through the miniature nozzle, d = 0.164 mm, are studied using the planar laser induced fluorescence technique. OH radical is excited on the $Q_{1}$(8) line of the $A^{2}$.SIGMA.$^{+.leq.X2}$ .PI.(1, 0) band transition (283.55 nm) and LIF signals are captured at the bands of (0, 0) and (1, 1) transition (306 ~ 326 nm) using the filters and ICCD camera. Hydroxyl radical (OH) profile for nozzle attached flame shows that OH radical populations at the flame sides and flame tip are larger than those at the base. But for the lifted flame (tribrachial flame) case, those are larger at the flame base than at the flame tip and flame sides. The OH radical is more dense near the center line of flame base at the blowing out. This fact proves the Chung and Lee's blowout theory-blowout occurs when the flame is anchored at the flame axis. axis.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.124-129
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• 2009

Antioxidant activities of the extract of red seaweed, Polysiphonia morrowii, were evaluated using several in vitro assay systems. Activity-guided fractionation revealed that the 90% MeOH fraction of the P. morrowii extract exhibited the highest antioxidant activity, and that this fraction had a high total phenolic content ($135.7{\pm}5.0\;mg$ gallic acid/g extract). Therefore, the antioxidant activities of the 90% MeOH fraction against 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical, reducing power, ferrous chelating, and hydrogen peroxide were investigated. The results revealed that the antioxidant activities of the 90% MeOH fraction were similar and/or superior to that of commercial antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, the ability of the 90% MeOH fraction to inhibit oxidative damage to DNA was assessed by measuring the conversion of the supercoiled pBR322 plasmid DNA to the open circular form. The 90% MeOH fraction was found to significantly protect this hydroxyl radical-induced DNA damage in a dose-dependent manner. Taken together, these findings suggest that the 90% MeOH fraction of P. morrowii extract and/or its constituents has the potential for use as a new bioresource of antioxidants.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.90-98
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• 2007

The antioxidant activities of water ($H_2O$) and ethanol (EtOH) extracts from hamcho (Salicornia herbacea L.) juice and cake prepared by enzymatic treatments were evaluated by in vitro assays against DPPH, superoxide, and hydroxyl radicals. Among the $H_2O$ and EtOH extracts from five different carbohydrases treated, the EtOH extract from viscozyme-treated hamcho cake had higher yield and phenolic content, and exhibited the strongest radical scavenging activity against DPPH ($IC_{50}=186.91\;{\mu}g/mL$), superoxide ($IC_{50}=87.54\;{\mu}g/mL$), and hydroxyl radicals ($IC_{50}=367.07\;{\mu}g/mL$). Antioxidant assay-guided fractionation and purification of the EtOH extract led to isolation and identification of five phenolic compounds, procatechuic, ferulic and caffeic acids, quercetin, and isorhamnetin. Most of these phenolic compounds exhibited considerable DPPH, superoxide, and hydroxyl radical scavenging activities, and in particular, caffeic and ferulic acids had stronger superoxide and hydroxyl radical scavenging activities than the well-known antioxidant radical scavenger, (+)-catechin (p<0.05). Quercetin and isorhamnetin were the primary compounds responsible for the strong antioxidant activity in the EtOH extract of the viscozyme-treated hamcho cake. Meanwhile, these five phenolic compounds were detected in the EtOH extract of the viscozyme-treated hamcho cake at the following levels (dry base of hamcho); procatechuic acid (1.54 mg%), caffeic acid (6.87 mg%), ferulic acid (8.45 mg%), quercetin (12.63 mg%), and isorhamnetin (6.65 mg%). However, three of these phenolic compounds (procatechuic, caffeic acid, and ferulic acids) were detectable in the $H_2O$ extract of viscozyme-treated hamcho juice. These results suggest that the EtOH extract of viscozyme-treated hamcho cake may be a potential source of natural antioxidants.