• Journal of the Korean Chemical Society
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• v.47 no.1
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• pp.43-46
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• 2003

From Portulaca oleracea which is widely distributed in Korea and has long been used as a folk medicine, two biophenolic glycosides, 3-hydroxy-1-(2-hydroxyethyl)phenyl-4-O-${\beta}$-D-glucopyranoside (1) and 2-(3,4-dihydroxyphenyl) ethyl-O-${\beta}$-D-glucopyranoside (2) were isolated using column chromatography and reversed-phase HPLC. $^{13}C$ NMR spectral assignment for these compounds was revised by the extensive 2-D NMR experiments such as NOESY, HMQC, and HMBC. These compounds showed a considerable antioxidant effect in DPPH assay system.

• Journal of the Korean Magnetic Resonance Society
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• v.17 no.2
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• pp.81-85
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• 2013

Various fluorine-containing materials are used in electronic devices like LCD display panels and Li-ion batteries. The structural conformation of fluorine in fluorinated materials is an important contributing factor that influences the chemical and physical properties. The conformation can be changed by heat and stress during manufacture or use. Understanding the conformational changes is critical for understanding the performance and durability of electronic devices. Solid-state NMR spectroscopy could be widely used for the analysis of various fluorine-containing materials for electronic devices. However, conventional CPMAS probes cannot be used for in-situ analysis of fluorine-containing electronic devices like LCD panels and Li-ion batteries. In this paper, we show the design, construction, and optimization of a $^{19}F-^{13}C$ double-resonance solid-state NMR probe for a 400MHz wide-bore magnet with a flat square coil for in-situ analysis of fluorine-containing electronic devices without observing fluorine background signals. This custom-built probe does not show any fluorine background signals, and can have higher efficiency for lossy samples.

• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.16-21
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• 2003

The methanol extractives from root bark of Ulmus davidiana var japonica nakai were fractionated with n-hexane, ethyl ether, ethyl acetate and waster, the water soluble fraction was also fractionated with silicagel column chromatograhy. The chemical structure of purifided compounds were identified with UV, IR, ¹H-NMR and ¹³C-NMR spectra and the antibacterial activities also were investigated. Two different antibacterial compounds (compound A and B) were fractionated with silicagel chromatography and TLC. Compounds B was identified as a catechin rahmnoside. The both of compounds had antibacterial activity on Staphylococcus aureus and Salmonella typhimurium.

• Archives of Pharmacal Research
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• v.1 no.1
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• pp.21-26
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• 1978

In connection with structure studies on triterpenoid glycosides from Phytolacca plants, full assignments of $^{13}C-NMR signals of phytolaccagenin and its glycosides, phytolaccoside B and E, have been presented.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.3
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• pp.77-85
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• 2020

Stable isotope enrichment in proteins is necessary for high-resolution nuclear magnetic resonance (NMR) experiments. Although methods for ¹³C, ¹⁵N and ²H-enrichment in prokaryotic cells are well established, full processing and correct folding of complex protein systems require higher organisms as the expression host. In the present study, we review recent efforts to enrich stable isotopes in mammalian cells for protein NMR studies.

• Natural Product Sciences
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• v.4 no.4
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• pp.221-225
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• 1998

A novel flavonol trisulphate, quercetin 7-methyl ether $3,3',4'-tri-O-KSO_3$ was isolated from the fresh leaves of Tamarix amplexicaulis (Tamaricaceae) along with the known flavonol mono sulphates, quercetin $3-O-KSO_3$ and quercetin 4'-methyl ether $3-O-KSO_3$. Structures were achieved through conventional analytical methods, including electrophoretic analysis and confirmed by FAB-MS and NMR spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.7 no.6
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• pp.433-438
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• 1986

Two new types of NMR shift reagents, one giving dipolar-only and the other giving contact-only shifts, can be prepared simply by mixing two appropriate $Ln(fod)_3$(Ln = Pr, Nd, Eu, and Yb) reagents in certain ratios. The $^1H$ and $^{13}C$ NMR spectra of pyridine-type substrates, quinoline and isoquinoline, whose paramagnetic shifts are normally a composite of contact and dipolar contributions with single lanthanide shift reagents, show the feasibility of this approach.

• Analytical Science and Technology
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• v.17 no.2
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• pp.173-179
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• 2004

The $BaTiO_3$ powders and thin films were prepared by an alkoxide modified sol-gel process (polymerization-complex route) using ethylene glycol. The stable starting (Ba-Ti)-mixed metal organic sol was made by addition of acetylacetone. The $BaTiO_3$ powders, which had a particle size of 40~77 nm, were crystallized from an amorphous to a tetragonal phase on annealing at 700 and $1100^{\circ}C$ for 1 h. From FT-IR, solid-state $^{13}C$ CP/MAS NMR spectroscopy and X-ray diffractometry, the trace of the Ba-Ti-oxycarbonate phase first appeared at $400^{\circ}C$. Hydrolyzed sol was spin coated on a quartz wafer at 3500 rpm for 60 s and pyrolyzed at $1100^{\circ}C$ for 1 h. After heat treatment, the coated layer became dense and smooth.

• Archives of Pharmacal Research
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• v.20 no.3
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• pp.201-205
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• 1997

A very high content (at least 0.23%) of ergosterol peroxide was isolated from Naematoloma fasciculare Karst. Not only ergosterol peroxide but also ergosterol showed very strong anticomplementary activity on the classical pathway, the $IC_{50}$ values being $5.0 {\mu}M$ and $1.0 {\mu}M$, respectively. The $ ^{1}H $and $^{13}C$ NMR data of ergosterol peroxide were revised and completely assigned by DEPT, $^{1}H-^{1}H$ COSY, HMQC and HMBC correlations.

• Archives of Pharmacal Research
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• v.6 no.1
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• pp.35-44
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• 1983

Interactions between thiamine.HCl and its disulfide derivatives TTFD. TPD and .alpha., .betha. cyclodextrins were investigated. By measuring the H-NMR, C-NMR chemical shifts, the assumption that cyclodextrin may from a inclusion complex with thiamines was supported qualitatively. To calculated the stability constants of them, anion exchange chromatography was applied. The simple, rapid HPLC method was proved to be pertinent thiamine/cyclodextrin system which was chemically unstable and less soluble.