• Journal of Korean Society of Environmental Engineers
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• v.38 no.12
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• pp.667-675
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• 2016

Nanoscale zero-valent iron (nZVI) has been effectively applied for environmental remediation due to its ability to reduce various toxic compounds. However, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of nZVIs. A modified indophenol method was suggested to determine reducing activity of nZVI. The method was originally developed to determine aqueous ammonia concentration, but it was further modified to quantify phenol and aniline. The assay focused on analysis of reduction products rather than its mother compounds, which gave more accurate quantification of reductive activity. The suggested color assay showed superior selectivity toward reduction products, phenol or aniline, in the presence of mother compounds, 4-chlorophenol or nitrobenzene. Reaction conditions, such as reagent concentration and reaction time, were optimized to maximize sensitivity. Additionally, pretreatment step using $Na_2CO_3$ was suggested to eliminate the interference of residual iron ions. Monometallic nZVI and bimetallic Ni/Fe were investigated with the reaction. The substrates showed graduated reactivity, and thus, reduction potency and kinetics of different materials and reaction mechanism was distinguished. The colorimetric assay based on modified indophenol reaction can be promises to be a useful and simple tool in various nZVI related research topics.

• The Journal of Korean Medicine
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• v.27 no.2 s.66
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• pp.122-133
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• 2006

Objectives : The amyloid $\beta$-protein ($A\beta$) is the principal component of the senile plaques characteristic of Alzheimer's disease (AD) and elicits a toxic effect on neurons in vitro and in vivo. Many environmental factors including antioxidants and proteoglycans modify $A{\beta}toxicity$. In this study, we have investigated the protective effects of water- and organic solvent-extracts of Hemerocallis fulva root fractions pre-extracted with methanol on $A\beta$-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. Methods : For this study, we used MTT reduction assay for detection of protective effects of water- and organic solvent-extracts of Hemerocallis fulva root fractions pre-extracted with methanol on $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells. We also used cell-based $\beta$-secretase assay system to investigate the inhibitory effect of water- and organic solvent-extracts of Hemerocallis fulva root on $\beta$-secretase activity. Results : We previously reported that methanol extracts of Hemerocallis fulva root strongly attenuated cytotoxicity induced by the three $A\beta$ fragments ($A{\beta}_{25-35},\;A{\beta}_{1-42}\;A{\beta}_{1-43}$) to both SK-N-MC and PC12 cells. In the present study, we found that butanol-, ethylacetate-, chloroform-, and water-extracts of Hemerocallis fulva root fractions pre-extracted with methanol had strong protective effects against $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells and inhibitory potency to $\beta$-secretase activity. Conclusion : These results suggest that butanol-, ethylacetate-, chloroform-, and water-extracts of Hemerocallis fulva root fractions pre-extracted with methanol may contain the protective component(s) against $A\beta$-induced cell death in PC12 cells as well as inhibitory component(s) to $\beta$-secretase activity.

• Toxicological Research
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• v.21 no.4
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• pp.339-345
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• 2005

Aflatoxins are produced by Aspergillus flavus, parasiticus that grows in improperly stored cereals. Aflatoxin $B_1\;(AFB_1)$ is a potent hepatocarcinogen in a variety of experimental animals including human beings. In spite of a high attention to the hepatocarcinogenecity of aflatoxins, the relative toxicity of other types $(AFB_2,\;AFG_1\;and\;AFG_2)$ of the toxins is not fully clarified. Sprague-Dawley male rats were orally administered with $AFB_1,\;AFB_2,\;AFG_1\;and\;AFG_2$ at the dose of 250, 1250, and $2500\;{\mu}g/kg$ body weight. Animals were then killed at 12, 24 or 48 hrs following aflatoxin adminstration. Subsequently the relative weight of liver was measured and histopathological examination on the liver was performed. Level of 8-OxodG and expression of ras gene in the liver was determined. The relative liver weights at high doses of $AFB_1\;and\;AFG_1$ was significantly low. The treatment of $AFB_1$ at the high dose of $2500\;{\mu}g/kg$ showed vacuolar degeneration and centrilobular hepatic necrosis with inflammatory cells. The pathological changes by $AFB_2\;AFG_1,\;and\;AFG_2$ were not clearly found. The formation of 8-OxodG by $AFB_1$ increased in a dose-dependent manner up to 24 hrs after a single treatment of $AFB_1$ thereafter decreased to the level of the control. The treatments of $AFB_2\;AFG_1,\;and\;AFG_2$ showed an inconsistent pattern in the formation of 8-OxodG in the liver of rats with increasing time. The expression of ras oncogene in the liver by $AFB_1$ at the dose of $1250\;{\mu}g/kg$ was increased twice compared to the control. The treatments of $AFB_2\;AFG_1,\;and\;AFG_2$ at all doses decreased the expression of ras in the liver. These results in the present study indicate that $AFB_1$ among aflatoxins with low comparable levels is the most toxic as determined by early biomarkers such as 8-OxodG formation and ras expression. However, the levels of 8-OxodG and ras as biomarkers were not useful to predict the relative hepatocarcinogenicity of aflatoxins to $AFB_1$ in the present model. Further studies are required to look for other biomarkers to predict carcinogenic potency of aflatoxins.

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.707-711
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• 2006

Phase 2 enzymes are transcriptionally induced by a wide variety of chemical agents and natural products, and their induction plays a critical role in protection against chemical carcinogens and other toxic xenobiotics. The activity of the methanol extract and fractions of paprika (Capsicum annuum L.) was examined in murine Hepa1c1c7 cells for the induction of nicotinamide adenine dinucleotide (phosphate) NAD(P)H/quinone reductase (QR). The ethyl acetate (EtOAc) fraction induced QR activity in a dose-dependent manner in the concentration range of 10 to $500\;{\mu}g/mL$ with a maximum of a 3.3-fold increase in induction. The EtOAc fraction also showed high QR induction potency in Ah-receptor-defective mutant of Hepa 1c1c7 cells ($BP^rcl$ cells), which indicates that this fraction is a monofunctional inducer of QR. These results suggest that useful cancer chemopreventive materials could be isolated from EtOAc fraction of Paprika.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.261-267
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• 2005

Phase II enzymes are transcriptionally induced by synthetic chemical agents and natural products, and such induction plays critical roles in protection against chemical carcinogens and other toxic xenobiotics. To discover natural products for use as cancer chemopreventive agents, the ability of Citrus aurantium Linn (Jikak) to induce activities of quinone reductase (QR) and glutathione S-transferase (GST) in wild-type murine hepatoma cell line (Hepa 1c1c7) and Ah-receptor-defective mutant of the same cell line (Bprcl) was investigated. Hexane and chloroform fractions of C. aurantium Linn (Jikak) at doses not exhibiting cytotoxicity were effective inducers of QR (${\sim}1.8-fold$) and GST (${\sim}1.5-fold$) in Hepa 1c1c7 cells, whereas showed low QR induction potency in Bprcl cells, which indicates they have weak monofunctional action. Results suggest C. aurantium Linn (Jikak) as potentially useful cancer chemopteventive agent.

• Journal of Food Hygiene and Safety
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• v.19 no.1
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• pp.1-8
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• 2004

This study was executed to determine the cumulative dietary risk of PAHs exposed by food ingestion. Food samples including barbecued beef, barbecued pork, grilled chicken, ham, bacon and vegetable oil which were collected from food markets. These samples were saponified, extracted and cleaned up to purify PAHs, and then the purified sample solutions were analyzed by HPLC-FL. Generally, the levels of total PAHs in barbecued beef (0.2 ppb), bacon (0.3 ppb), barbecued pork (0.7 ppb), ham (0.8 ppb), and vegetable oil (1.2 ppb) were low, whereas the level of total PAHs in grilled chicken (9.3 ppb) was significantly high. For the exposure assessment of PAHs due to food ingestion, PAHs levels converted into TEQ$_{BaP}$, the average body weight for 20-73 age group and consumed levels of food proposed from report on the National Health and Nutrition Survey were used. The estimated lifetime average daily intake of dietary PAHs was 4.32${\times}$10$^{-4}$ $\mu\textrm{g}$-TEQ$_{BaP}$kg/day as the mean value. The dietary risk adjusted to cancer potency of benzo(a)pyrene as 7.3 (mg/kg/day)$^{-1}$ was 3.44${\times}$10$^{-6}$ based on current data.ata.