• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.25-33
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• 2013

Clenbuterol and ractopamine, which are ${\beta}$-agonists, have been misused as a growth promoting agent in meat producing animals. Clenbuterol was banned for veterinary drug in Korea because of its problems regarding safety. Due to their adverse effects, such as cardiovascular and central nervous diseases on human health proper control and monitoring should be conducted. The existing analytical method of clenbuterol and ractopamine in the Food code was improved through our present study. The bovine muscle samples were subjected to enzymatic hydrolysis, extracted with ethyl acetate and defatted by hexane-methanol partitioning. A molecular imprinted polymer (MIP) solid phase extraction cartridge was used for clean-up and LC-MS/MS was operated in positive multiple reaction monitoring (MRM). Clenbuterol-$d_9$ and ractopamine-$d_3$ were used as an internal standard. The renewed method was validated according to the CODEX guideline. The limits of quantitation for clenbuterol and ractopamine were 0.2 and 0.5 ${\mu}g/kg$, respectively. The mean recoveries ranged in 104.2-113.5% for clenbuterol and in 107.6-118.1% for ractopamine. The improved method was able to save both time and expenses.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.177-183
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• 2013

In this study, the antioxidative activities and component analysis of Broussonetia kazinoki SIEB (B. kazinoki). extracts were investigated. B. kazinoki extract showed the effective free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}=8.53{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activity ($OSC_{50}$) of the ethyl acetate fraction of B. kazinoki. extracts in the luminol-dependent $Fe^{3+}-EDTA/H_2O_2$ system was $1.69{\mu}g/mL$. The ethyl acetate fraction of B. kazinoki. extracts also exhibited more prominent cellular protective effects (${\tau}_{50}$, 183.3 min at $10{\mu}g/mL$) than that of typical antioxidant $\alpha$-tocopherol (${\tau}_{50}$ = 38.00 min) in the $^1O_2$-induced photohemolysis of human erythrocytes. Components of the ethyl acetate fraction obtained from B. kazinoki extracts were analyzed by TLC, HPLC chromatogram, LC/ESI-MS/MS and $^1H$-NMR. Consequently, Components, components were identified as the kazinol J of kazinol series and luteolin (2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-chromenone) of flavonoid series having antioxidant activities. These results indicate that extract/ fraction of B. kazinoki can be used as antioxidants in biological systems, particularly skins exposed to UV radiation by quenching and/or scavenging $^1O_2$ and other ROS, and protecting cellular membranes against ROS. Thus, the extract/fraction of B. kazinoki could be applicable to new cosmeceuticals.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.236-246
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• 2016

The aim of this study was to develop an analytical method for the determination of pyribencarb and its metabolite KIE-9749 in agricultural commodities. The experiment was performed with a range of concentrations $0.05{\sim}2.5{\mu}g/g$ in apple, green pepper, potato, hulled rice, soybean, pear, peach, grape and cucumber. Each samples were extracted with acetone and cleaned by dichloromethane/saline water partition and purified with Florisil solid phase extraction (SPE) cartridge and aminopropyl SPE cartridge. Pyribencarb and KIE-9749 were separated and quantified by HPLC/UVD at 265nm using acetonitrile and water as mobile phase. The recoveries of pyribencarb and KIE-9749 were within 78.3~108.4% and 73.9~113.7% with RSD below 12.2% and 15.0%, respectively. The limits of quantification (LOQ) were both $0.05{\mu}g/g$. LC/ESI-MS/MS was optimized for confirmation of residue identity.

• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.51-57
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• 2014

In this study, the antioxidative effects and component analysis of Polygonum aviculare (P. aviculare) extracts were investigated. The ethyl acetate and the aglycone fraction from P. aviculare extracts were more active than (+)-${\alpha}$-tocopherol and $\small{L}$-ascorbic acid, which are known as strong antioxidants for their antioxidative activity by the DPPH method and chemiluminescence assay. The cellular protective effects of fractions of P. aviculare on the rose-bengal sensitized photohemolysis of human erythrocytes, increased in a concentration dependent manner ($1-10{\mu}l$). In particular, the ethyl acetate fraction at a concentration of $10{\mu}l$ showed the most prominent protective effect among all the extracts (${\tau}_{50}$, 314.70 min). TLC and HPLC chromatogram of the ethyl acetate fraction of P. aviculare extracts revealed 3 main bands (PA8, PA5, PA6) and peaks (peak 1, peak 2, peak 3), which were identified as myricetin-3-O-rhamnoside (myricitrin, PA8, peak 1), quercetin-3-${\alpha}$-rhamnoside (quercitrin, PA6, peak 3) by LC/ESI-MS/MS and $^1H$-NMR respectively. These results indicate that fractions from P. aviculare could be applicable to new functional cosmetics as antioxidants.

• Analytical Science and Technology
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• v.18 no.4
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• pp.271-277
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• 2005

Urea in blood has been measured as an effective marker for diagnosis of renal function. Urea which is e end-product of nitrogen containing metabolites such as proteins is filtered through glomeruli of kidneys and then excreted as urine. If the renal function is deteriorated, the urea concentration in blood will be increased, from which the healthiness of renal function is judged. In order to improve the confidence of diagnosis results, the results must keep traceability chain to certified reference materials, which was certified by primary reference method. In this study, we proposed isotope dilution-liquid chromatography/mass spectrometry (ID-LC/MS) as a candidate primary method, in which $15^N_2$-urea is used as an internal reference material. The developed method is highly accurate in principle and is convenient as it does not require cumbersome derivatization. 0.1 mmol/L ammonium chloride was selected as a mobile phase for HPLC because it provided low interference in MS analysis of relatively low molecular weighted urea. HPLC and MS were connected with an electrospray ionization (ESI) interface of positive mode, which provided high sensitivity and reproducibility. The developed method was validated with internationally recognized reference materials, and we have obtained satisfactory results in an international ring trial. The expanded uncertainty calculated according to ISO guide was 1.8% at 95% confidence interval. The developed method is being used as a primary reference measurement method such as for certification of serum certified reference materials (CRMs).

• Journal of Plant Biotechnology
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• v.41 no.1
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• pp.1-9
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• 2014

So far it has been generally considered that proteomic approaches are very useful for studying plant-microbes interaction. In this review, recent studies based on papers published from 2010 to 2013 have investigated proteomics analysis in various interaction during plant-fungal pathogen infection by means of gel-based proteomics coupled with mass spectrometry (MS)-based analysis. In rice, three papers focused on rice-Magnaporthe oryzae interaction were mainly reviewed in this study. Interestingly, another study showed proteomic changes in rice inoculated with Puccinia triticina, which is not only an fungal pathogen in wheat and but also results to the disease resistance with non-host defense manner in rice. Additionally, proteomics analysis has been widely subjected to understand defense mechanism during other crops (wheat, tomato, strawberry and mint) and their fungal pathogen interaction. Crops inoculated are analyzed to identify differentially regulated proteins at various tissues such as leaf and apoplast using 2-DE analysis coupled with various MS approaches such as MALDI-TOF MS, nESI-LC-MS/MS and MudPIT, respectively. Taken together, this review article shows that proteomics is applicable to various organisms to understand plant-fungal pathogen interaction and will contribute to provide important information for crop disease diagnosis and crop protection.

• Korean Journal of Environmental Agriculture
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• v.32 no.4
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• pp.315-322
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• 2013

BACKGROUND: This study was performed for the identification and quantification of glucosinolate (GSL) contents in seven varieties of rapeseed (Brassica napus L.) sprouts cultivated under dark and light conditions. METHODS AND RESULTS: Crude glucosinolates (GSLs) were desulfated by treating with aryl sulfatase and purified using diethylaminoethyl sepharose (DEAE) anion exchange column. Individual GSLs were quantified using high-performance liquid chromatography (HPLC) with electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Eleven GSLs including six aliphatic (progoitrin, sinigrin, glucoalyssin, gluconapoleiferin, gluconapin, and glucobrassicanapin), four indolyl (4-hydroxyglucobrassicin, glucobrassicin, 4-methoxyglucobrassicin, and neoglucobrassicin) and one aromatic (gluconasturtiin) were identified based on the fragmentation patterns of MS spectrum. Aliphatic GSLs were noted as the predominant group with average 85.2% of the total contents. The most abundant GSLs were progoitrin which was ranged at $8.14-118.68{\mu}mol/g$ dry weight (DW). The highest total GSL amounts were documented in 'Hanra' ($146.02{\mu}mol/g$ DW) under light condition and 'Mokpo No. 68' ($86.67{\mu}mol/g$ DW) in dark condition, whereas the lowest was in 'Tamra' (30.13 and $14.50{\mu}mol/g$ DW) in both conditions. The sum of aliphatic GSLs attributed > 80% in all varieties, except 'Tamra' (67.7% and 64.9% in dark and light conditions, respectively) in the total GSL accumulation. Indolyl GSLs were ranged $2.41-15.73{\mu}mol/g$ DW, accounted 2.78-33.6% of the total GSLs in rapeseed varieties. CONCLUSION(S): These results provide valuable information regarding potential beneficial GSL contents individually. This study attempts to contribute to knowledge of the nutritional properties of the different varieties of rapeseed plants. These results may be useful for the evaluation of dietary information.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.227-234
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• 2019

An analytical method was developed for the determination of oxytetracycline in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After the samples were extracted with methanol, the extracts were adjusted to pH 4 by formic acid and sodium chloride was added to remove water. Dispersive solid phase extraction (d-SPE) cleanup was carried out using $MgSO_4$ (anhydrous magnesium sulfate), PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed with LC-MS/MS using ESI (electrospray ionization) in positive ion MRM (multiple reaction monitoring) mode. The matrix-matched calibration curves were constructed using six levels ($0.001{\sim}0.25{\mu}g/mL$) and coefficient of determination ($r^2$) was above 0.99. Recovery results at three concentrations (LOQ, $10{\times}LOQ$, and $50{\times}LOQ$, n=5) were from 80.0 to 108.2% with relative standard deviations (RSDs) less than of 11.4%. For inter-laboratory validation, the average recovery was in the range of 83.5~103.2% and the coefficient of variation (CV) was below 14.1%. All results satisfied the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for oxytetracycline determination in agricultural commodities. This study could be useful for safety management of oxytetracycline residues in agricultural products.

• Molecules and Cells
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• v.40 no.9
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• pp.621-631
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• 2017

Vaccinia-related kinase 1 (VRK1) and VRK3 are members of the VRK family of serine/threonine kinases and are principally localized in the nucleus. Despite the crucial roles of VRK1/VRK3 in physiology and disease, the molecular and functional interactions of VRK1/VRK3 are poorly understood. Here, we identified over 200 unreported VRK1/VRK3-interacting candidate proteins by affinity purification and LC-MS/MS. The networks of VRK1 and VRK3 interactomes were found to be associated with important biological processes such as the cell cycle, DNA repair, chromatin assembly, and RNA processing. Interactions of interacting proteins with VRK1/VRK3 were confirmed by biochemical assays. We also found that phosphorylations of XRCC5 were regulated by both VRK1/VRK3, and that of CCNB1 was regulated by VRK3. In liver cancer cells and tissues, VRK1/VRK3 were highly upregulated and its depletion affected cell cycle progression in the different phases. VRK3 seemed to affect S phase progression and G2 or M phase entry and exit, whereas VRK1 affects G1/S transition in the liver cancer, which could be explained by different interacting candidate proteins. Thus, this study not only provides a resource for investigating the unidentified functions of VRK1/VRK3, but also an insight into the regulatory roles of VRK1/VRK3 in biological processes.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.88-94
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• 2008

Two sugar biosynthetic cassette plasm ids were used to direct the biosynthesis of a deoxyaminosugar. The pOTBP1 plasmid containing TDP-glucose synthase (desIII), TDP-glucose-4,6-dehydratase (desIV), and glycosyltransferase (desVII/desVIII) was constructed and transformed into S. venezuelae YJ003, a strain in which the entire gene cluster of desosamine biosynthesis is deleted. The expression plasmid pOTBP3 containing 4-aminotransferase (gerB) and 3,5-epimerase (orf9) was transformed again into S. venezuelae YJ003-OTBP1 to obtain S. venezuelae YJ003-OTBP3 for the production of 4-amino-4,6-dideoxy-L-glucose derivatives. The crude extracts obtained from S. venezuelae ATCC 15439, S. venezuelae YJ003, and S. venezuelae YJ003-OTBP3 were further analyzed by TLC, bioassay, HPLC, ESI/MS, LC/MS, and MS/MS. The results of our study clearly shows that S. venezuelae YJ003-OTBP3 constructs other new hybrid macrolide derivatives including 4-amino-4,6-dideoxy-L-glycosylated YC-17 (3, [M+ $Na^+$] m/z=464.5), methymycin (4, m/z=480.5), novamethymycin (6, m/z=496.5), and pikromycin (5, m/z=536.5) from a 12-membered ring aglycon (10-deoxymethynolide, 1) and a 14-membered ring aglycon (narbonolide, 2). These results suggest a successful engineering of a deoxysugar pathway to generate novel hybrid macrolide derivatives, including deoxyaminosugar.