• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.145-151
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• 2007

To investigate the chemical constituents of Acer tegmentosum, the bark were collected, air-dried and extracted with 70% aqueous acetone. Then it was successively partitioned with n-hexane, $CH_2Cl_2$, EtOAc and $H_2O$. Repeated Sephadex LH-20 column chromatography on the EtOAc soluble fraction gave five phenolic compounds. Their structures were elucidated as (+)-catechin (1), (-)-epi-catechin (2), Q-epicatechin-3-O-gallate (3), gallic acid (4) and 6'-0-galloylsalidroside (5) on the basis of spectroscopic evidences using $^1H-NMR$, $^{13}C-NMR$, 2D-NMR and MS spectroscopy, (-)-epicatechin-3-Ogallate (3), gallic acid (4), 6'-Ogalloylsalidroside (5) have not been reported in this plant yet.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.512-516
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• 1996

Sophorose $(2-O-{\beta}-D-glucopyranosyl-D-glucopyranose)$ was chemically synthesized from D-glucopyranose through six steps of chemical reactions with the yield of 21%. The chemical structures of sophorose and some compounds obtained during reactions were confirmed by interpretations of spectral data, NMR, IR, etc.

• 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.

• Analytical Science and Technology
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• v.20 no.5
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• pp.400-405
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• 2007

The comparative analysis of glycerin in cosmetic samples was carried out by LC/MS and $^1H$ NMR spectrometry. For the LC/MS analysis, aqueous solution was controlled in strong basic condition with sodium hydroxide, and benzoyl chloride was added to the solution for the derivatization of glycerin. The derivative was extracted using pentane and analyzed by the LC/MS. For the $^1H$ NMR analysis, sample was directly dissolved in $D_2O$ solvent without pretreatment. The quantitative analysis of glycerin was done by $^1H$ NMR ERETIC method. The analysis results of LC/MS and $^1H$ NMR showed that the calibration curves were a good linearity with $r^2=0.9991$ in the range of 0.1 to $10{\mu}g/mL$ and $r^2=1$ in the range of 25 to $500{\mu}g/mL$, respectively.

• Journal of the Korean Magnetic Resonance Society
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• v.18 no.2
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• pp.82-88
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• 2014

Three bicyclic and one monocyclic sesquiterpenoids were isolated from the marine sponge Topsentia species. Their planar structures were completely determined from a combination of extensive 1D and 2D NMR experiments, and also the relative stereochemistry on the chiral centers were established by the ROESY experiment. Compound 1 was determined as a new stereoisomer. Furthermore, the NMR spectral data for compounds 2 and 4, of which have not been reported, were listed. Four compounds did not show any cytotoxicity, instead compound 4 exhibited moderate antifungal activity against Candida albicans.

• 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 Magnetic Resonance Society
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• v.4 no.2
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• pp.125-132
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• 2000

The detailed $^1$H and $^{13}$ C NMR assignments of a novel sucrose isovaleryl ester isolated from the seed of Euphorbia Lathyris L., were achieved by one-and two-dimensional techniques. The new sucrose ester was characterized as an $\alpha$-D-glucopyranoside, 3,4,6-tris-O-(3-methyl-1-oxobutyl)-$\beta$-D-fructofuranosyl, 2,6-bis(3-methylbutanoate); sucrose 4,7,8,11,12-pentaisovalerate by MS and NMR experiments.

• Journal of Plant Biotechnology
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• v.34 no.3
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• pp.207-212
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• 2007

This study describes a simple and rapid method for quantitative determination of $\gamma$-aminobutyric acid (GABA) using $^1H$ NMR spectroscopy from whole cell extracts of plant suspension cultures. When 9 cell lines derived from 8 species of higher plants maintained in liquid Marashige and Skoog (MS) medium supplemented with 1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) were subjected to $^1H$ NMR, a cell line of Coriandrum sativum L. exhibited the highest level of GABA. The level reached up to 16.9 mg/dry wt when cells were cultured in MS medium supplemented with 0.5 mg/L 2,4-D after 3 weeks of incubation. The method for quantitative determination of GABA using $^1H$ NMR established in this study could be applied to high-throughput screening of various plant resources for GABA production and the cell suspension culture system of C. sativum could be further developed for commercial production of GABA.

• Natural Product Sciences
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• v.27 no.2
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• pp.122-127
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• 2021

A new steroidal saponin, (23S,24S)-spirosta-5,25(27)-diene-1𝛽,3𝛽,23,24-tetrol 1-O-((2,3-diacetyl-α-L-rhamnopyranosyl)-(1→2)-[𝛽-D-xylopyranosyl-(1→3)]-α-L-arabinopyranoside)-24-O-𝛽-D-glucopyranoside (humilisoside) together with the known 𝛽-sitosterol 3-O-glucopyranoside, adenosine, dioscin, and methylprotodioscin were isolated from the leaves of Dracaena humilis. Their structures were elucidated by spectral techniques including mass spectrometry (ESIMS, HRESIMS, tandem MS-MS), 1D NMR (¹H, ¹³C NMR), 2D NMR (HSQC, ¹H-¹H COSY, HMBC, NOESY), chemical method as well as by comparison with spectroscopic data reported in the literature. The chemotaxonomic significance of the isolation of these compounds is discussed. This is the first report on the phytochemical investigation of D. humilis.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1145-1148
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• 1999

1H NMR spectra of methyl-, ethyl-, propyl-, isopropyl-, butyl-, N-methylethyl-, N-methylpropyl-, and N-methylisopropylamine coordinated to the paramagnetic 11-tungstocobalto(II)silicate anion (SiW11Co) in dimethylsulfoxide-d6 or dimethylformamide-d7 are reported. For these complexes the ligand exchange is slow on the NMR time scale and pure 1H NMR signals have been observed at room temperature. No complex is detected in D2O. From the pseudocontact shifts of the CH2 and CH3 groups in ethylamine the energy of the gauche conformers with respect to the anti conformer is estimated. Two diastereotopic protons in the CH2 group of N-methylethylamine have quite different chemical shifts especially at low temperatures (e.g. 48.5 vs. 19.4 ppm at -10℃). This may be attributed mainly to the different positions of the two protons in the most stable (gauche) conformer.