• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1745-1750
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• 2013

A novel green aqueous mobile phase modified with room temperature ionic liquids (RTILs) was employed in the absence of volatile organic solvents or ion-pairing reagents to analyze thiamine, a very polar compound, by reverse phase high performance liquid chromatography (RP-HPLC). Due to its strongly hydrophilic nature, thiamine was eluted near the column dead time ($t_0$) using a mobile phase without adding RTILs or ion-pairing reagents, even if a 100% aqueous mobile phase, which has weak elution power under reverse phase conditions, was used. Thus, 1-ethyl-3-methyl-imidazolium hexafluorophosphate ([EMIM][$PF_6$]), which has the strongest chaotropic effect, was selected as a mobile phase additive to improve retention and avoid baseline disturbances at $t_0$. Various mobile phase parameters such as cation moiety, chaotropic anion moiety, pH and concentration of RTILs were optimized to determine thiamine at the proper retention time. Method validation was performed to assess linearity, intra- and inter-day accuracy and precision, recovery and repeatability; all results were found to be satisfactory. The developed method was also compared to the current official United States Pharmacopoeia (USP) and Korean Pharmacopoeia (KP) methods using an organic mobile phase containing an ionpairing reagent by means of evaluating various chromatographic parameters such as the capacity factor, theoretical plate number, peak asymmetry and tailing factor. The results indicated that the proposed method exhibited better efficiency of thiamine analysis than the official methods, and it was successfully applied to quantify thiamine in pharmaceutical preparations.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.207-211
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• 1997

Laboratory experiments were conducted to the potential ability of bioremediation with bentazon such as determining the absorption, translocation, and metabolism of $^{14}C-Bentazon$ in minari after foliar applications. The absorption and translocation of $^{14}C-bentazon$ were compared when applied to foliar of minari. In foliar applications, 21% was observed in treated leaves, 66% remained in water extracts of leaf surfaces, and 13% was found in the epicuticular wax layer after 2d. Translocation of the herbicide from treated leaves to roots was very low(79 to 9%). Analysis of methanol-soluble extracts of $^{14}C$ indicated that more than 60% of the foliarapplied herbicide was metabolized in all plant sections after 2d. However, 77% or more of the bentazon was degraded in roots and shoots 2d after root absorption. The major metabolite in these experiments was an unknown compound that was less polar than bentazon and 6- and 8-hydroxy bentazon.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.712-720
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• 2022

In this study, we evaluated the production and photoreactivity of CDOM of two polar phytoplanktons - Phaeocystis antarctica and Phaeocystis pouchetii, in order to find out UV effects on phytoplanktons. In visible region, CDOM in media of both phytoplanktons under UV-R decreased during 48hrs incubation period. However, in UV region CDOM decreased 30 % in the media of P. antarctica, but increased 10% in media of P. pouchetii, compared to CDOM concentrations of control after 48 hr incubation. This result indicates that biota in polar environment would not well protected from UV-R harmful effect when P. antarctica is dominant because of loss of CDOM, but when P. pouchetii is dominant species, production of UV absorbing organic matter could play more efficiently for UV screening for marine biota. Also we confirmed that FDOM of humic substance (C-peak) produced by these phtoplanktons under UV-R stress were well matched with fluorescence characteristics of the UV-protecting compound, MAAs. This finding shows that Phaeocystis pouchetti with low photoreactivity would contribute to DOM pool of polar marine environment under stratification by global warming.

• Food Science and Industry
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• v.51 no.2
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• pp.127-135
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• 2018

The action of antioxidants was different depending on the environments where antioxidants were located. Although basic mechanisms of lipid oxidation and antioxidants were related each other, their contribution on the degree of oxidation was different. In thisreview, terminology on antioxidant properties were defined such as antioxidant activity and antioxidant capacities. In addition, antioxidant mechanisms including primary and secondary antioxidants or hydrogen donating or electron transferring antioxidants were introduced. Also, the impact of physical points of view and antioxidant polar paradox were introduced. Depending on the types of food matrice including bulk oil, oil-in-water emulsion (O/W), or solid state, antioxidant actions showed different degree and this point was explained in detail.

• Journal of the Korean Chemical Society
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• v.40 no.7
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• pp.509-514
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• 1996

The three-dimensional metal complex inclusion compound $Cd(pn)Ni(CN)_4{\cdot}0.5NO_2C_6H_5$(pn: 1,2-diaminopropane=propylenediamine) crystallizes in the orthorhombic space group, $Pn2_1$a, (a=13.868(5), b=26.591(4), c=7.840(1)${\AA}$, V=2891(1)${\AA}^3$, Z=4), R=0.054 for 2800 independent reflections. The host structure of the inclusion compound appears the same one(T-type) of inclusion compound with branched aliphatic-guest molecule. The nitrobenzeneguest molecule attains the stable position in the nodal channel of T-type by placing the polar nitro group between the pn-amino groups at the node and the bulky aromatic ring in the antinodal zone of the channel. The substituted aromatic guest molecule is accommodated in the host structure of metal complex $Cd(pn)Ni(CN)_4$ with channel cavity.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.557-565
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• 2014

We report the effect of basal-plane stacking faults (BSFs) on X-ray diffraction (XRD) of non-polar (11$\underline{2}$0) a-plane GaN films with different $SiN_x$ interlayers. Complete $SiN_x$ coverage and increased three-dimensional (3D) to two-dimensional (2D) transition stages substantially reduce BSF density. It was revealed that the Si-doping profile in the Si-doped GaN layer was unaffected by the introduction of a $SiN_x$ interlayer. The smallest in-plane anisotropy of the (11$\underline{2}$0) XRD ${\omega}$-scan widths was found in the sample with multiple $SiN_x$ layers, and this finding can be attributed to the relatively isotropic GaN mosaic resulting from the increase in the 3D-2D growth step. Williamson-Hall (WH) analysis of the (h0$\underline{h}$0) series of diffractions was employed to determine the c-axis lateral coherence length (LCL) and to estimate the mosaic tilt. The c-axis LCLs obtained from WH analyses of the present study's representative a-plane GaN samples were well correlated with the BSF-related results from both the off-axis XRD ${\omega}$-scan and transmission electron microscopy (TEM). Based on WH and TEM analyses, the trends in BSF densities were very similar, even though the BSF densities extracted from LCLs indicated that the values were reduced by a factor of about twenty.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2335-2341
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• 2014

Chemical investigation on the methanol extract of the starfish Ctenodiscus crispatus resulted in the isolation of five steroids, (22E,$24{\zeta}$)-26,27-bisnor-24-methyl-$5{\alpha}$-cholest-22-en-$3{\beta}$,5,$6{\beta}$,$15{\alpha}$,25-pentol 25-O-sulfate (1), (22E,24R,25R)-24-methyl-$5{\alpha}$-cholest-22-en-$3{\beta}$,5,$6{\beta}$,$15{\alpha}$,25,26-hexol 26-O-sulfate (2), (28R)-24-ethyl-$5{\alpha}$-cholesta-$3{\beta}$,5,$6{\beta}$,8,$15{\alpha}$,28,29-heptaol-24-sulfate (3), (25S)-$5{\alpha}$-cholestane-$3{\beta}$,5,$6{\beta}$,$15{\alpha}$,$16{\beta}$,26-hexaol (4), and ${\Delta}7$-sitosterol (5). Their structures were identified by extensive spectroscopic analyses, including 1D, 2D NMR and MS and chemical methods. Compound 4 showed cytotoxicity against human hepatoma HepG2 and glioblastoma U87MG cells via inhibition of cell growth and induction of apoptosis. Induction of apoptosis by 4 was demonstrated by cell death, DNA fragmentation, increased Bax/Bcl-2 protein ratio and the activation of caspase-3, caspase-9 and poly (ADP-ribose) polymerase (PARP).

• Natural Product Sciences
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• v.13 no.4
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• pp.378-383
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• 2007

Phenathrene derivatives, such as batatasins, are well-known constituents in Dioscorea Rhizoma. Although phenanthrenes have been reported as representative compounds in this plant, standard markers for quality control have been focused on the polar constituents (saponins and purine derivatives). Herein, simple, rapid and reliable HPLC method was developed to determine 3,5-dimethoxyphenanthrene-2,7-diol (DMP) and batatasin-I (BA-I) as non-polar standard maker compounds of Dioscorea Rhizoma. DMP and BA-I were analyzed under optimized HPLC conditions [column: Columbus $5{\mu}$ C18 100A ($30{\times}4.6mm$ i.d., $5{\mu}m$; mobile phase: $H_2O$ with 0.025% $CH_3COOH$ (v/v) for solvent A and $CH_3CN$ with 0.025% $CH_3COOH$ (v/v) for solvent B, gradient elution; flow rate: 2 mL/min; detection: 260 nm), and each experiment was finished within 13 min. Good linearity was achieved in the range from 0.5 to $10.0{\mu}g/mL$ for each compound, and intra- and inter-day precision were in the acceptable levels. The recovery test were performed with three different Dioscorea Rhizoma samples (D. opposita, D. batatas and D. japonica), and showed its accuracy values in the range of 97.2 - 102.8% for three different concentrations of DMP and BA-I. The content levels of DMP and BA-I were ranged under 0.0020%. These results demonstrated that amounts of DMP and BA-I are easily determined with conventional HPLC-UV-DAD method although the content levels were lower than those of saponins and allantoin in Dioscorea Rhizoma. This HPLC method could be used for quality control of various Dioscorea preparations.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.368-374
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• 2020

BACKGROUND: The residual analysis of polar pesticides has remained a challenge. It is even more difficult to simultaneously analyze multiple polar pesticides. Diquat, paraquat, and chlormequat are typical examples of highly polar pesticides. The existing methods for the analysis of diquat, paraquat and chlormequat are complex and time consuming. Therefore, a simple, quick and effective method was developed in the represent study for simultaneous analysis of diquat, paraquat and chlormequat in animal products, meat and fat using UPLC-MS/MS. METHODS AND RESULTS: Sample extraction was carried out using acidified acetonitrile and water and re- extracted with acidified acetonitrile and combine the extracts followed by centrifugation. The extract was then cleaned up with a HLB cartridge after reconstitution with acidic acetonitrile and water. The method was validated in quintuplicate at three different concentrations. The limits of detection (LOD) and quantification (LOQ) were 0.0015 and 0.005 mg/L, respectively. Matrix suppression effect was observed for all of the analytes. A seven point matrix matched calibration curve was constructed for each of the compound resulted excellent linearity with determination coefficients (R2) ≥ 0.991. Accuracy and precision of the method was calculated from the recovery and repeatability and ranged from 62.4 to 119.7% with relative standard deviation less than 18.8%. CONCLUSION: The recovery and repeatability of the developed method were in the acceptable range according to the Codex Alimentarius guideline. The developed method can be applied for the routine monitoring of diquat, paraquat, and chlormequat in animal products, meat and fat.

• Nutrition Research and Practice
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• v.8 no.3
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• pp.257-266
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• 2014

BACKGROUND/OBJECTIVE: Licorice has been shown to possess cancer chemopreventive effects. However, glycyrrhizin, a major component in licorice, was found to interfere with steroid metabolism and cause edema and hypertension. The roasting process of licorice modifies the chemical composition and converts glycyrrhizin to glycyrrhetinic acid. The purpose of this study was to examine the anti-carcinogenic effects of the ethanol extract of roasted licorice (EERL) and to identify the active compound in EERL. MATERIALS/METHODS: Ethanol and aqueous extracts of roasted and un-roasted licorice were prepared. The active fraction was separated from the methylene chloride (MC)-soluble fraction of EERL and the structure of the purified compound was determined by nuclear magnetic resonance spectroscopy. The anti-carcinogenic effects of licorice extracts and licochalcone A was evaluated using a MTT assay, Western blot, flow cytometry, and two-stage skin carcinogenesis model. RESULTS: EERL was determined to be more potent and efficacious than the ethanol extract of un-roasted licorice in inhibiting the growth of DU145 and MLL prostate cancer cells, as well as HT-29 colon cancer cells. The aqueous extracts of un-roasted and roasted licorice showed minimal effects on cell growth. EERL potently inhibited growth of MCF-7 and MDA-MB-231 breast, B16-F10 melanoma, and A375 and A2058 skin cancer cells, whereas EERL slightly stimulated the growth of normal IEC-6 intestinal epithelial cells and CCD118SK fibroblasts. The MC-soluble fraction was more efficacious than EERL in inhibiting DU145 cell growth. Licochalcone A was isolated from the MC fraction and identified as the active compound of EERL. Both EERL and licochalcone A induced apoptosis of DU145 cells. EERL potently inhibited chemically-induced skin papilloma formation in mice. CONCLUSIONS: Non-polar compounds in EERL exert potent anti-carcinogenic effects, and that roasted rather than un-roasted licorice should be favored as a cancer preventive agent, whether being used as an additive to food or medicine preparations.