• Natural Product Sciences
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• v.3 no.1
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• pp.11-13
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• 1997

From the methanolic extract of defatted tender leaf of Camellia sinensis a new 4-hydroxy angular furocoumarin $C_{12}H_8O_5$, m.p. $212^{\circ}C$, was isolated using high-speed counter-current chromatographic technique. The structure of the compound was established as 4-hydroxy-2'-methoxy angular furocoumarin on the basis of physical methods viz. $^1H$ NMR, $^{13}C$ NMR and MS.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.317-322
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• 2011

• Journal of the Korean Magnetic Resonance Society
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• v.14 no.1
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• pp.18-27
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• 2010

The NMR spectrum and spin-lattice relaxation times, $T_1$, of the $^{1}H$ nuclei in $(NH_{4})_{2}Cd_{2}(SO_{4})_{3}$ single crystals were obtained. The two minima in $T_1$ in the paraelectric phase are attributed to the reorientational motions of the $NH_{4}^{+}$ groups. The $^{1}H\;T_1$ of the $(NH_{4})_{2}Cd_{2}(SO_{4})_{3}$ crystals can be described with Bloembergen- Purcell-Pound (BPP) theory. The experimental value of $T_1$ can be expressed in terms of an isotropic correlation time ${\tau}_H$ for molecular motions by using the BPP theory, and determine the role of protons in these processes.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.770-775
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• 1993

Chemical structure of poly(ethylene terephthalate-co-1, 4-cyclohexylene dimethylene terephthalate), P(ET-CT) copolyesters was investigated by High Resolution NMR analysis. The copolymer composition and isomeric ratio were determined by methylene resonance peaks which were separated into three peaks corresponding to ET, trans CT and cis CT units, respectively. The copolymer sequence distribution was evaluated from the carbon resonance peaks connected to carbonyl groups in benzene, indicating died distribution. According to statistics model, these copolyesters are almost random copolymers. The copolymer sequence distribution could be simulated and its averaged length was calculated by random copolymer statistics.

• Journal of the Korean Magnetic Resonance Society
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• v.23 no.4
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• pp.93-97
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• 2019

Black ginger (Kaempferia parviflora) is a short-lived ginger plant with dark purple colored root and is known to be effective in treating diabetes and obesity. To find out the difference in the characteristics of the black ginger according to the variety of production, 1D proton NMR experiments were performed on 4 types of black gingers from different regions. The NMR spectra of all black ginger showed the characteristic peaks of the polymethoxy flavone compounds, and the chemical shifts and intensity of peaks showed slight differences depending of the type of black ginger implying the difference in molecular environment. These initial NMR experiments can be applied to the identification of the diversity of black ginger in physiological function according to the climate of regions using SNIF-NMR (Site-specific Natural Isotope Fractionation studied by NMR).

• Journal of Pharmaceutical Investigation
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• v.39 no.1
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• pp.43-49
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• 2009

Aspirin or acetylsalicylic acid, a member of the salicylate family, is frequently used as an analgesic, antipyretic, anti-inflammatory and antiplatelet drug. Because aspirin is chemically unstable in water and heat for tablet formulation, additives including lubricants are used in preparing aspirin tablets, using a dry-granulation process. Aspirin tablets are produced by a number of manufacturers which usually use their own unique combination of additives during the manufacturing process. In this study, we employed an NMR based metabolomics technique to identify the manufacturers of various aspirin tablets. Aspirin tablets from six different companies were analyzed by 1H 400 MHz NMR. The acquired data was then integrated and processed by principal component analysis (PCA). Based on the NMR data, we were able to identify peaks corresponding to acetylsalicylic acid in all of the six samples, whereas different NMR patterns were found in the aromatic and aliphatic regions depending on the unique additive used. These observations led to the conclusion that the differences in the NMR patterns among the different aspirin tablets were due to the presence of additives.

• Journal of the Korean Magnetic Resonance Society
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• v.3 no.1
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• pp.44-51
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• 1999

An enzyme derived conformational changes of cobalamine is thought to be important in the homolytic cleavage of Co-C bond which is the first step of catalytic Cl-cycle of coenzyme B12-dependent enzymes. Modern 2D-NMR and NMR-based distance geometric studies were carried out to determine the 3D structure of corrin ring. Homonuclear and heteronuclear correlation NMR experiments were performed for complete 1H-NMR signal assignments. Distances between numerous proton pairs were deduced based on the NOE cross peak intensities and subsequently used as input into the distance geometry program for the 3D structure determination. The detailed 3D structure from the present NMR-based analysis was compared with the result from X-ray crystallographic study, which revealed greater conformational changes occur in benzimidazole group and sugar ring than in macrocyclic corrin and tetrapyrrole. In addition, the distance geometry used in this study was found to be quite useful for NMR-based structure determination of medium-sized molecules that give poor NOE effects arising from their intermediate tumbling rate ($\omega$$\tau$c 1.0).

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.44-52
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• 1980

Ionic dissociation rates of $\alpha$-chlorobenzyl ethyl ether in each solvent of toluene-$d_8$ and carbon tetrachloride were measured by the method of dynamic NMR spectroscopy. The spin system of these 1H NMR spectra was $AB_3$. The theoretical spectrum was calculated by computer simulation of dynamic NMR spectra, which agreed very well with observed spectra. From this computer simulation, the ionic dissociation rate constant k was obtained, and by Eyring plot with it, slope and intercept length was gained, from which kinetic parameters were calculated.The easiness of ionic dissociation depended upon solvent polarity. Activation enthalpy was 4.7 kcal/mole in toluene-$d_8$, 10.7 kcal/mole in carbon tetrachloride, and activation entropy was -35. 8 e.u. in toluene-$d_8$, -14.4 e.u. in carbon tetrachloride. It was understood that though the ${\Delta}H^{neq}$ value was small, this ionic dissociation had an easier procession in nonpolar solvents with increasing temperatures. Considering that the ionic dissociation could be thought as the first step of $S_N1$ mechanism, attention might be paid to the results that the value of ${\Delta}S^{neq}$ had a large negative value in comparison with a small ${\Delta}H^{neq}$.

• Korean Journal of Agricultural Science
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• v.45 no.3
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• pp.455-461
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• 2018

Deoxynivalenol (DON), a Fusarium mycotoxin, causes health hazards for both humans and livestock. Therefore, the aim of this study was to investigate the metabolic profiles of the liver, serum, and urine of piglets fed DON using proton nuclear magnetic resonance ($^1H-NMR$) spectroscopy. The $^1H-NMR$ spectra of the liver, serum, and urine samples of the piglets provided with feed containing 8 mg DON/kg for 4 weeks were aligned and identified using the icoshift algorithm of MATLAB $R^2013b$. The data were analyzed by multivariate analysis and by MetaboAnalyst 4.0. The DON-treated groups exhibited discriminating metabolites in the three different sample types. Metabolic profiling by $^1H-NMR$ spectroscopy revealed potential metabolites including lactate, glucose, taurine, alanine, glycine, glutamate, creatine, and glutamine upon mycotoxin exposure (variable importance in the projection, VIP > 1). Forty-six metabolites selected from the principal component analysis (PCA) helped to predict sixty-five pathways in the DON-treated piglets using metabolite sets containing at least two compounds. The DON treatment catalyzed the citrate synthase reactions which led to an increase in the acetate and a decrease in the glucose concentrations. Therefore, our findings suggest that glyceraldehyde-3-phosphate dehydrogenase, citrate synthase, ATP synthase, and pyruvate carboxylase should be considered important in piglets fed DON contaminated feed. Metabolomics analysis could be a powerful method for the discovery of novel indicators underlying mycotoxin treatments.

• Journal of the Korean Chemical Society
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• v.23 no.2
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• pp.94-98
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• 1979

From the catalytic reductions of the respective 2-amino-, and 2-nitro-3,4-dihydro-5,6-dimethoxy-1(2H)-naphthalenone, a major reduction product of 2-amino-5,6-dimethoxy-1,2,3,4-tetrahydro-naphthalene was obtained, along with a minute amount of rearranged product, 5,6-dimethoxy-1,2,3,4-tetrahydro-2(1H)-naphthalenone. The unusual formation of 5,6-dimethoxy-1,2,3,4-tetrahydro-2(1H)-naphthalenone was verified on the basis of ir, and nmr spectra, and elemental analysis. A plausible mechanism for the rearrangement is proposed.