• Applied Biological Chemistry
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• v.42 no.4
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• pp.351-355
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• 1999

In order to find anti-dementia drugs from natural products, prolyl endopeptidase inhibitors were purified from Puerariae Flos by consecutive solvent partition, followed by silica gel, Sephadex LH-20, and HPLC. Four isoflavonoid inhibitors were isolated and identified as tectorigenin, genistein, 5,7-dihydroxy-4',6-dimethoxyisoflavone, and 5-hydroxy-6,7,4'-trimethoxyisoflavone by means of instrumental analyses including $^{1}H-$, $^{13}C-$, $^{2}D-NMR$ and MS and $IC_{50}$ values against PEP were 5.30 ppm$(17.7\;{\mu}M)$, 10.39 ppm$(38.5\;{\mu}M)$, 13.92 ppm$(44.3\;{\mu}M)$, and 20.61 ppm$(62.8\;{\mu}M)$, respectively. Some previous mistakes in $^{13}C-NMR$ assignment were revised by careful investigation of HMBC and HMQC data.

• Applied Biological Chemistry
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• v.36 no.2
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• pp.134-137
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• 1993

Yongia sonchifolia Max. has been used as raw materials of traditional Kimchi and medicinal herb in Korea. This study was performed to investigate biologically active components in the plant. First, the writer carried out the experiment of antitumor screening test against Sarcoma-180A and the cytotoxic activity against Chinese hamster V-79 cells with methanol extract of the plant. And the aqueous solution of the extract from roots of Youngia sonchifolia Max. was partitioned into n-hexane. The concentrated extract of n-hexane layer was chromatographed on silica gel column and developed with n-hexane and ethylacetate. Two yellow elutes, on concentration, were recrystallized from ethylacetate, and the $R_f$ value of TLC of the crystal was 0.43. After analysis by $^{1}H-NMR$, $^{13}C-NMR$ and MS to confirm the structure, the author could identify the compound as bauerenyl acetate, a naturally occurring pentacyclic triterpene. The crystal was colorless plate and m.p. was $280{\sim}282^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1323-1329
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• 2020

To characterize the molecular structure of PhE-gal synthesized using Escherichia coli 𝛽-gal, NMR (¹H- and ¹³C-) spectroscopy and mass spectrometry of PhE-gal were conducted. ¹H NMR spectrum of PhE-gal showed multiple peaks corresponding to the galactosyl group, which is an evidence of galactosylation on 2-phenylethanol (PhE). Downfield proton peaks at 𝛿_H 7.30~7.21 ppm showed the presence of aromatic protons of PhE as well as benzyl CH₂ protons at 𝛿_H 2.88 ppm. Up field proton peaks at 𝛿_H 4.31 ppm, 4.07 ppm and multiple peaks from 𝛿_H 3.86~3.38 ppm are indicative of galactocylation on PhE. ¹³C NMR spectrum revealed the presence of 12 carbons suggestive of PhE-gal. Among 12 carbon peaks from PhE-gal, the four peaks at 138.7, 129.0, 128.6 and 126.5 were assigned aromatic carbons in the phenyl ring. Three peaks at 129.0, 128.6 and 126.5 showed high intensities, indicating CH aromatic carbons. ¹³C NMR data of PhE-gal showed 6 monosaccharide peaks from galactose and 2 peaks from aliphatic chain of PhE, indicating that PhE-gal was galactosyl PhE. The mass value (sodium adduct ion of PhE-gal, m/z = 307.1181) from mass spectrometry analysis of PhE-gal, and ¹H and ¹³C NMR spectral data were in good agreement with the expecting structure of PhE-gal. We are expecting that through future study it will eventually be able to develop a new additive with low cytotoxicity.

• 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.

• Polymer(Korea)
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• v.39 no.2
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• pp.287-292
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• 2015

Characterization of a series of bio-based terpolymers containing various amounts of ethylene glycol, 1,4-cyclohexylene dimethanol, and isosorbide units were studied by $^1H$ NMR and $^{13}C$ NMR. The NMR results revealed that they had all random microstructures and that their sequence distribution was affected by the content of isosorbide. From DSC data for the terpolymer series investigated, it was observed that the glass transition temperature increased mainly as the content of isosorbide increased. The glass transition temperatures of terpolymers were estimated from the composition by extended Fox equation.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.59-65
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• 1993

We isolated Actinomycetes strain GMT 1155 and purified the active compound, MT 1155, on the morphological reversion of ts/NRK cell from the isolate. MT 1155 was identified as toyocamycin having antifungal and antitumor activities from physico-chemical properties and UV, IR, $^1H$-NMR, $^13C$-NMR and mass spectrum. MT 1155 showed the morphologically reversional activity on ts/NRK cell and the cytotoxicity on CTLL cell at the final concentrations of 1.7 JlM and 0.2 11M, respectively and its $IC_{50}$ value on protein kinase A enzyme was 2.3 $\mu$M. Also it had strong antifungal activity against several pathogenic fungi but not antibacterial activity. And it did not inhibit both protein kinase C activity and the bleb-formation of K562 cell induced by phorbol esters.

• Polymer(Korea)
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• v.26 no.4
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• pp.452-461
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• 2002

In this study, the effect of various concentrations of antioxidants on thermo-oxidative degradation of polyamide 6 was investigated. Unstabilized and stabilized polyamides 6 were subjected to long-term oven aging in ambient atmosphere at 70~$160^{\circ}C$. All of specimens were discolored within 100 hr at temperature range of 70~$160^{\circ}C$. Optimum antioxidant concentration was determined from the data of mechanical properties, yellowness index and relative viscosity. The synergistic effect of each primary and secondary antioxidant concentrations was not observed. Yellowing phenomenon was explained by using NMR, IR and EA. Different carbonyl groups were detected by $^{13}C$/NMR. During thermooxidative degradation, oxygen consumptions were determined by EA. The lifetime after long-term aging was predicted using Arrhenius equation.

• Elastomers and Composites
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• v.43 no.4
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• pp.281-287
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• 2008

Using solid state $^{13}C$ NMR, polybutadiene rubber vulcanizates were qualitatively and quantitatively analyzed. In the filled conventional system of BR vulcanizate accelerated with TBBS, addition to the olefinic double bond and substitution in the $\alpha$ position to the double bond occurred simultaneously. Also the latter $\alpha$ substitution reaction was faster than the former addition reaction at initial reaction time. In addition, it was suggested that double bond-addition-polysulfide structures might be modified into 5-membered and 6-membered cyclic structures in overcure time. These chain modifications were correlated with the decrease in the chemical crosslink density in overcure time.

• Elastomers and Composites
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• v.48 no.1
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• pp.85-91
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• 2013

In this study, we synthesized a terpolymer consisting of ethylene, 1-hexene, and styrenic monomer using a metallocene catalyst and cocatalyst ststem. The styrenic monomers empolyed as the third monomer were styrene, p-methylstyrene, and 4-tert-butylstyrene. The structure and composition of the terpolymers were characterized using $^{13}C$ NMR and $^1H$ NMR. Catalytic activity, polymer yield, molecular weight and molecular weight distribution of the terpolymers were analyzed. We also determined the glass transition temperature(Tg), crystallinity and thermal properties of the terpolymers by DMA, WAXS and TGA.

• Analytical Science and Technology
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• v.11 no.1
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• pp.73-78
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• 1998

The reverse detection heteronuclear multiple quantum coherence, HMQC study of metcyano complex of horse myoglobin(MbCN) has provided the complete assignment of hyperfine shifted resonances of heme carbons attached with proton(s). The application of HMQC experiment to the paramagnetic low-spin MbCN gives clear $^1H$ and $^{13}C$ coherences for the paramagnetic amino acid residues as well as heme side chains, and can be extended to the low-spin paramagnetic hemoprotein derivative for the assignment of natural abundance $^{13}C$ resonances. This assignment strategy can avoid possible ambiguities that may result from the sole utilization of $^1H$ nuclear Overhauser effect for the assignment of heme $^1H$ signals resonating in the diamagnetic region. The resulting 2,4-vinyl ${\alpha}$-carbons and 7-propionate ${\beta}$-carbon follow anomalous anti-Curie behavior, and are indicative of incoplanarity with heme plane. Magnetic/electronic asymmetry of heme induced by proximal histidine(His) makes spread that the hyperfine shifted heme carbon resonances over the range of 250 ppm at $25^{\circ}C$. These heme carbon resonances would be the much more sensitive probe than those of proton resonances in analyzing the nature of heme electronic structure of myoglobin.