• Journal of Sericultural and Entomological Science
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• v.42 no.2
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• pp.93-98
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• 2000

This study was designed to investigate the effect of silkworm powder on oxygen radicals and their scavenger enzymes in brain membrances of SD rats. Hydroxyl radical (OH) levels resulted in a considerable decreases in brain mitochondria fraction. Superoxide radical (O$_2$) levels were a slightly decreased in brain cytosol fraction. Lipid peroxide (LPO) and Oxidized protein (OP) levels were significantly decreased in brain mitochondria and microsomes fraction. Mn-superoxide dismutase (SOD) activity was remarkably increased in the mitochondria fraction. Cu and Zn-SOD activities were effectively increased in brain cytosol fraction. GSHPx activity was considerably increased in brain cytosol fraction. These results suggest that anti-aging effect of silkworm plays an effective role in attenuating an oxidative stress and increasing a scravenger enzyme activity in brain membranes.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.227-231
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• 1993

The role of ascorbate as an antioxidant in the prevention and cure of disease that result from free radicals has been of considerable interest and controversy lately. As an antioxidant, we can expect it to protect against radiation damage caused by free radicals that are produced when radiation, especially sparsely ionizing radiation, interacts with living tissues. The plasma and whole blood concentration of ascorbate was analyzed before and just after the radiation therapy for the purpose of estimating the consumption amount of ascorbate during radiotherapy. Whole blood ascorbate was decreased from 1.82 mg/dl to 1.58 mg/dl, plasma ascorbate was decreased from 1.13 mg/dl to 1.08 mg/dl, and urine ascorbate was decreased from 9.33 mg/dl to 6.96 mg/dl after radiotherapy. Although the difference was not significant statistically, further human study should be followed to define the role of ascorbate as a radioprotector.

• Journal of Microbiology
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• v.44 no.4
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• pp.466-471
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• 2006

In this study, we attempted to characterize the biomolecular effects of an atmospheric-pressure cold plasma (APCP) system which utilizes helium/oxygen $(He/O_2)$. APCP using $He/O_2$ generates a low level of UV while generating reactive oxygen radicals which probably serve as the primary factor in sterilization; these reactive oxygen radicals have the advantage of being capable to access the interiors of the structures of microbial cells. The damaging effects of plasma exposure on polypeptides, DNA, and enzyme proteins in the cell were assessed using biochemical methods.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.292-293
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• 2002

대기 중에서 HOx(OH, H $O_2$) 라디칼은 가장 중요한 산화제로서 광화학 반응의 핵심적 역할을 한다. 이러한 OH 라디칼의 정확한 농도를 측정하기 위한 여러 가지 시도가 있었으나, 그 존재량이 적고 수명이 짧기 때문에 측정에 많은 어려움이 있다. 간접적인 측정에 근거한 모델링과 계산적인 이론 값에 의하면 대류권에서의 전 지구적 평균 OH 라디칼의 농도는 대략 $10^{6}$molecules $cm^{-3}$이고, H $O_2$ 라디칼의 농도는 $10^{8}$molecules $cm^{-3}$정도로 추정된다. (중략)

• Journal of Pharmaceutical Investigation
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• v.25 no.4
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• pp.313-322
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• 1995

The covalent conjugation of human recombinant superoxide dismutase (hrSOD) with trichloros-triazine activated polyethylene glycol (PEG) 5000 formed soluble conjugates with molecular weight of 92KD, which retained $90{\sim}98%$ of original activity with a markedly prolonged plasma half-life of enzyme activity. The effect of hrSOD-PEG conjugates on acetaminophen (ACP)-induced hepatotoxicity was tested in male rats which were pretreated with 3-methylcholanthrene. HrSOD-PEG conjugates inhibited the hepatotoxicity produced by ACP, on the other hand, native hrSOD had no protective effect. The above results indicated that oxygen radicals might participate in the mechanism of the ACP-induced hepatotoxicity and that polymer conjugated-protein drugs with prolonged half-lives could be employed as an effective therapeutic agent.

• Environmental Analysis Health and Toxicology
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• v.8 no.3_4
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• pp.23-32
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• 1993

This study was designed to elucidate the mechanism of nephrotoxicity caused by antitumor agent tetraphosphine platinum (II) complex (RC-1), which was synthesized as a tetraphosphine Pt (II) derivatives recently. Rats treated with RC-1 (20mg/kg/day) showed the increase of BUN value and malondialdehyde contents in kidney homogenate, compared to the control and which means the lipid peroxidation was a main cause of nephrotoxicity. In order to investigate the cytotoxic mechanism of RC-1, we also tested and revealed the generation of oxygen free radicals derived from neutrophil stimulated by RC-1 and interaction of the oxygen free radicals with the erythrocyte membrane. From the above results, we suggest that nephrotoxicity of general platinum (II) antitumor compounds as well as RC-1 were inhibited by radical scavengers.

• Environmental Analysis Health and Toxicology
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• v.18 no.3
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• pp.175-182
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• 2003

Bisphenol A shares similarities in structure, metabolism and action with DES, a known human teratogen and carcinogen. Bisphenol A, a monomer of polycarbonate and epoxy resins, has been detected in canned food and human saliva. The purpose of the this study was to evaluate the cytotoxicity, cell proliferation of bisphenol A In the presence of a rat liver S9 mix, contaning cytochrome P450 enzymes, and Cu (II). In the present study, Bisphenol A in combination with Cu (II) exhibited a enhancement in cytotoxicity which were inhibited by free radical scavengers. The content of malondialdehyde, an end product of lipid peroxidation, was also found to increase with concentration of bisphenol A. Also, we examined the change of CuZn-SOD, Mn-SOD, catalase and GPx activities in the MCF-7 cells exposed to bisphenol A. The activities of CuZn-SOD, CPx, catalase were found to decrease with bisphenol A concentration. Meanwhile, the activity of Mn-SOD was unchanged. This indicated that elevated oxidative stress caused by imbalance between the production and removal of free radicals occurred in cells.

• Preventive Nutrition and Food Science
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• v.4 no.2
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• pp.92-96
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• 1999

The effects of aqueous extracts from Korean commercial teas on excessive free radicals were examined utilizing spin trapping, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical and lipid peroxidation. A potent scavenging effect of green tea and oriental senna tea was dound using sipin trapping. The most effective teasagainst the DPPH radical was green tea, followed inorder by pine leak tea, Chinese gutta percha tea and orietnal senna tea. Similar to the effects of DPPH radical , green tea, pine leaf tea, Chinese gutta percha tea and oriential senna tea had an inhibitory effect on lipid peroxidation. These findings predict that Korean tea is a promising material for scavenging free radicals, and for curing diseases related to free-radical reactions.

• Korean Journal of Plant Resources
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• v.23 no.3
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• pp.207-213
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• 2010

Hovenia dulcis Thunb fruits were successively extracted with hot water, water, methanol, ethyl acetate, and chloroform. The crude extracts were investigated for potential antioxidant by measuring scavenging against DPPH free radicals, reducing power, superoxide radicals, and protection of protein damage and cultured cells from a lethal dose of hydrogen peroxide ($H_2O_2$). In all chemical assays used, the hot water extract of H. dulcis fruits, which contained $61.14{\pm}2.57$ (Tannic acid mg/g extract, n=3) of total phenolic compounds contents exhibited highest activity in in vitro models of DPPH free radical scavenging activity, reducing power assay, superoxide radical scavenging activity and protection of protein damage. In addition, the hot water extract protected cultured RAW 264.7 macrophages from a lethal dose of $H_2O_2$ and reduced reactive oxygen species level in RAW 264.7 cells.

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1657-1660
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• 2004

Several critical geometries associated with the rearrangement of $CH_3SNO_2\;to\;CH_3SONO$ are calculated with the density functional theory (DFT) method and compared with those of the ab initio molecular orbital methods. There are two probable pathways for this rearrangement, one involving the transition state of an oxygen migration and the other through the homolytic decomposition to radicals. The reaction barrier via the transition state is about 60 kcal/mol and the decomposition energy into radicals about 35 kcal/mol, suggesting that the reaction pathway via the homolytic cleavage to radical species is energetically favorable. Since even the homolytic cleavage requires large energies, the rearrangement reaction is unlikely without the aid of catalysts.