• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 1998년도 가을 학술발표회 프로그램
• /
• pp.1-1
• /
• 1998

Advanced (Chemical) oxidation processes (AOP) differ from most conventional ones in that hydroxyl radical(OH.) is considered to be the primary oxidant. Hydroxyl radicalcan react non-selectively with a great number of organic and inorganic chemicals. The typical rate constants of true hydroxyl radical reactions are in the range of between 109 to 1012 sec-1. Many processes are possible to generate hydroxyl radical. These include physical and chemical methods and their combinations. Physical means involves the use of high energy radiation such as gamma ray, electron beam, and acoustic wave. Under an applied high energy radiation, water molecules can be decomposed to yield hydroxyl radicals or aqueous electrons. Chemical means include the use of conventional oxidants such as hydrogen peroxide and ozone, two of the most efficient oxidants in the presence of promoter or catalyst. Hydrogen peroxide in the presence of a catalyst such as divalent iron ions can readily produce hydroxyl radicals. Ozone in the presence of specific chemical species such as OH- or hydrogen peroxide, can also generate hydroxyl radicals. Finally the combination of chemical and physical means can also yield hydroxyl radicals. Hydrogen peroxide in the presence of acoustic wave or ultra violet beam can generate hydroxyl radicals. The principles for hydroxyl radical generation will be discussed. Recent case studied of AOP for water treatment and other environmental of applications will be presented. These include the treatment of contaminated soils using electro-Fenton, lechate treatment with conventional Ponton, treatment of coal for sulfur removal using sonochemical and the treatment of groundwater with enhanced sonochemical processes.

• Toxicological Research
• /
• 제14권3호
• /
• pp.301-306
• /
• 1998

This experiment was carrid out to know the effects of heating and serum on hydroxyl radicals in embryonic mouse forebrain (cerebrum) culture. The heating to mouse embryonic cerebrum cells in culture was done in a water bath at 43${\circ}C$ for 60min. After that, two supernatants were prepared at 20 hrs and 48 hrs respectively after heat treatment to the brain cells. To find out the heating effects on neuron cells, mouse cerebrum cells (13 embryonic day) were cultured in hydroxyl radical generation system composed of 20mU/ml glucose oxidase (GO system), using condition of normal culture media (MEM, 5% serum, 5% $CO_2$or supernatant prepared after heating at 43${\circ}C$ for 60 min in a water bath. Supernatant prepared at 20 hrs after heat treatment had a greater protective effects against hydroxyl radical than supernatant prepared at 48 hrs after heat treatment . Otherwise, the protective effect of serum against hydroxyl radicals in the cultured brain cells is higher than that in the heat treatment. These results indicated that serum in culture media reduced cytotoxicity of hydroxyl radicals in mouse forebrain culture, also that heat treatment showed the protective effects against hydroxyl radicals generated with 20mU/ml GO system in mouse forebrain culture.

• Toxicological Research
• /
• 제14권4호
• /
• pp.541-545
• /
• 1998

This experiment carried out to compare the protective effects of some antioxidants to hydroxyl radicals in embryonic mouse whole brain tissue culture. The ICR mouse whole brain (13 embryonic day) was cultured in hydroxyl radical system in which radicals were generated by 20 mU / ml glucose oxidase (GO). In this experiment, to make ferrous iron from ferric iron, iron as an accelerator, and ascorbic acid as a reductant were used. For comparison of the protective effects to hydroxyl radicals, antioxidants such as desferrioxamine (DFX), laccase. water or ethanol extracts from Rhus Vemiciflua Stokes (RVS), and $\alpha$-tocopherol were used, because they relate to metal ion. The results of this experiment showed that all antioxidants protected effectively the cytotoxicity from hydroxyl radicals in the brain cultures. More than 70% of cell viabilities among different antioxidants was at 1 mM DFX, 1.43 $\mu\textrm{m}$ laccase, 12.5 $\mu\textrm{m}$ water extract, 12.5 $\mu\textrm{m}$ ethanol extract and 50 $\mu\textrm{m}$ $\alpha$-tocopherol individually, compared with 20 mU/ml GO alone. In comparison to the antioxidative activities of antioxidants, laccase and extracts from RVS showed strong antioxidative effects even at low concentration.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• 제10권S_3호
• /
• pp.127-137
• /
• 2001

The sonochemical Process has been applied as a treatment method and was investigated its effect on the decomposition of humic substances(HS). The reaction kinetics and mechanisms in the Process of sonochemical treatment for humic substances(HS) in wastewater have also been discussed. It was observed that the metal ions such as Fe(II) and Mn(II) showed catalytic effects, while Al(III), Ca(II), and Mg(II) had inhibitory effects on the decomposition of humic substances in sonochemical reaction with hydrogen peroxide. Experimental results also showed factors such as hydrogen peroxide dose affected the formation of disinfection by-products. Two trihalomethanes, chloroform and dichlorobromomethane were formed as major disinfection by-products during chlorination. The mechanism of radical reaction is controlled by an oxidation process. The radicals are so reactive that most of them are consumed by HS radicals and hydroxyl radicals can be acted on organic solutes by hydroxyl addition, hydrogen abstraction, and electron transfer. The depolymerization and the radical reaction of HS radicals appear to occur simultaneously. The final steps of the reaction are the conversion of organic acids to carbon dioxide.

• Korean Journal of Acupuncture
• /
• 제22권4호
• /
• pp.57-65
• /
• 2005

대계는 전통 한의학에서 약용 물질로 널리 쓰이고 있으므로, 대계의 약침을 조제하여 항산화적 활성을 검증해 보았다. 실험의 재료로 쓰인 대계는 동국대학교 한의과대학 부속 한방 병원에서 구입하여 사용하였고 (경상북도 경주), 이를 약침액으로 조제한 후 동결 건조 방법으로 5.1 %의 분말을 회수 하였다. 대계 약침액의 항산화 능력을 측정하기 위하여 DPPH자유기의 소거능은 Gyamfi et al. 의 방법을 따랐고, superoxide radicals $(O_2^-{\cdot})$ 소거능은 Gotoh et al.의 방법을 일부 수정하여 사용하였다. Hydroxyl radicals의 직접적인 소거능과 iron ions 사이의 관계는 deoxyribose assay를 통하여 검증하였다. 이상의 실험 결과에서 1) Non-site-specific scavenging assay (hydroxyl radicals, OH) 및 2) Site-specific scavenging assay (chelate iron ions) 그리고 3) 전산화 효과에서 모두 대계 약침액은 농도 의존적인 저해 효과를 보였으며, 특히 pro-oxidant 실험에서는 산화를 촉진하지 않는 것으로 나타났다. 끝으로 hydorxyl radical에 의하여 매개되는 DNA의 분절 효과를 적절하게 방어하는 것을 관찰할 수 있었다. 따라서 대계 약침액은 산화적 스트레스를 직접적으로 방어 하고, 다양한 산화적 손상에 의한 병증을 예방할 것으로 사료된다.

• Applied Biological Chemistry
• /
• 제47권3호
• /
• pp.293-299
• /
• 2004

거대배아미 에탄올 추출물의 항산화활성을 지질과산화 억제활성 및 활성산소종의 소거활성을 중심으로 일반미와 대조하여 검토하였다. 연구 결과, 발아처리는 전반적으로 환원력 및 지질과산화 억제활성, superoxide radical 및 hydroxyl radical 소거활성을 상승시켰으며, 발아처리에 의한 항산화 활성의 증가현상이 화청거대배아미에서 가장 뚜렷하였다. Superoxide radical 소거작용에 있어서는 남풍거대배아미가 전체적인 소거활성은 높았으나, 발아처리에 의한 활성의 상승률은 역시 화청거대배아미가 가장 높았고, 그 작용기작은 시료에 의한 직접적인 radical 소거에 있는 것으로 나타났다. 생체 독성이 가장 큰 hydroxyl radical 소거활성을 조사한 결과, 화청거대배아미가 전체적인 소거활성 뿐 아니라, 발아처리에 의한 소거활성의 증가율도 가장 높았으며, 그 작용기작도 $Fe^{2+}$의 포족이 아닌 직접적인 라디칼 소거임이 밝혀졌다. 이와 같은 in vitro에서 관찰된 시료의 ROS 소거활성은 TPA하여 유도된 HL-60 세포의 ROS 생산을 억제하는데 유효하게 작용하였다.

• 한국자원식물학회지
• /
• 제22권6호
• /
• pp.489-497
• /
• 2009

In this study, we evaluated and compared the protective effects of two major constituents, baicalein and baicalin, against oxidative DNA and cell damages caused by hydroxyl radical. Antioxidant properties were evaluated using DPPH and hydroxyl radicals scavenging assays and $Fe^{2+}$ chelating assay. ${\varphi}X$ 174 RFI plasmid DNA and intracellular DNA migration assay were used to evaluate the protective effect against oxidative DNA damage. Also, MTT and lipid peroxidation assays were used to evaluate their protective effects against oxidative cell damage. Both baicalein and baicalin prevented intracellular DNA and cells from oxidative damage caused by hydroxyl radical via antioxidant activities. Baicalein demonstrated a stronger antioxidant activity in scavenging DPPH radicals and chelating $Fe^{2+}$ while baicalin scavenged hydroxyl radicals more efficiently. The differences in the level of baicalein and baicalin pose a different pathological pathway for each. The antioxidant activity of baicalin was due to its ability to scavenge hydroxyl radical whilst baicalein was a stronger $Fe^{2+}$ chelator. Further investigation to compare the molecular mechanisms of antitumor activities of baicalein and baicalin is vital to anticancer research.

• 대한한의학회지
• /
• 제26권3호
• /
• pp.204-214
• /
• 2005

Objectives : The verity extract of the Gagam-Hyungbang-Gihwang-tang (GHG) was assessed to determine the mechanisms of its antioxidant activity. Methods : The fellowing effects were measured : GHG exhibited a concentration-treatment; scavenging ${\alpha},\;{\alpha}-diphenyl-\beta-picrylhydrazyl$ (DPPH) radical, linoleic acid oxidation in a thiocyanate assay system, and superoxide anion, hydroxyl radical-induced DNA nicking. We investigated mRNA levels such as superoxide-dismutase. Results : The GHG extract showed dose-dependent free radical scavenging activity, including DPPH radicals, hydroxyl radicals, and superoxide anion, using different systems. The GHG was also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in Fenton's reaction mixture. Furthermore, SOD-1 mRNA expression levels increased in tat hepatoma H4IIE cells Conclusions : We expect that GHG will to helpful to the development of antioxidant activity treatments.

• Environmental Analysis Health and Toxicology
• /
• 제23권1호
• /
• pp.41-45
• /
• 2008

Algal fucoidan is a marine polysaccharide containing sulfur with a wide variety of biological activities including anti-inflammatory and anti-thrombotic effects. Although antioxidants can inhibit inflammatory signals through inhibiting activator protein-1 and/or nuclear factor-kappaB activation, it is obscure whether fucoidan directly scavenges oxy-radicals or indirectly regulates oxidant production and/or antioxidant defense system. The antioxidant activities of fucoidan against peroxyl radicals, peroxynitrites and hydroxyl radicals were determined by the total oxy-radical scavenging capacity (TOSC) assay. The specific TOSC values of fucoidan against peroxyl radicals, peroxynitrites or hydroxyl radicals were $282{\pm}60$, $43{\pm}1$ or $40{\pm}1\;TOSC/mg/mL$, respectively. These specific TOSC values against peroxyl radicals, peroxynitrites or hydroxyl radicals are 23, 12, or 13% of the specific TOSC values of glutathione, a positive control, respectively. These results suggest that fucoidan has direct oxy-radical scavenging capacity, which may be related with anti-inflammatory effect of fucoidan.

• Toxicological Research
• /
• 제23권3호
• /
• pp.263-269
• /
• 2007

Although taurine (2-aminoethanesulfonic acid) can inhibit oxidative stress in both animal and epidemiological studies, it is obscure whether taurine directly scavenges oxy-radicals or indirectly regulates oxidant production and/or antioxidant defense system. The reason for this discrepancy remains unknown but may be due, in part, to the lack of a validated assay system for evaluating oxy-radical scavenging capacity. The antioxidant activities of taurine and hypotaurine (2-aminoethanesulfinic acid), a precursor of taurine, against peroxyl radicals, hydroxyl radicals and peroxynitrites were determined by the total oxy-radical scavenging capacity (TOSC) assay and cell-based assay using H4IIE cells. tert-Butylhydroperoxide or hydrogen peroxide-induced cell toxicity determined by MTT assay was markedly inhibited by 10mM taurine or hypotaurine. The tert-butylhydroperoxide- or hydrogen peroxide-induced changes in oxidative stress markers, such as cellular glutathione and malondialdehyde, were ameliorated by 10mM taurine or hypotaurine. However, specific TOSC values calculated from the slope of the linear regression for taurine against peroxyl radicals, hydroxyl radicals or peroxynitrites were all less than 1 TOSC/mM. On the other hand specific TOSC values for hypotaurine against peroxyl radicals, hydroxyl radicals or peroxynitrites were 48, 2096, or 69 TOSC/mM, respectively. These results suggest that taurine protects cells against oxidative insults, which is not ascribed to directly scavenging activity of taurine against oxy-radicals. These results support the idea that the oxidation state of sulfur in antioxidants may be a determinant of oxy-radical scavenging capacity.