• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.183-192
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• 2014

For the structure determination of D-(+)-sucrose, which consists of ${\alpha}$-D-(+)-glucose and ${\beta}$-D-(+)-fructose, it was acetylated with acetic anhydride and triethyl amine, pyridine, zinc chloride, and sodium acetate as catalysts. The acetylated D-(+)-sucrose was acid-hydrolyzed using sulfuric acid and sodium chloride in methanolic solution. The structures of the reaction products were determined by $^1H$-NMR and $^{13}C$-NMR spectra. The yield of the acetylation indicated the high value in zinc chloride as 70% in zinc chloride catalyst. The acid-hydrolyzed product of the acetylated D-(+)-sucrose, 2,3,4,6,1',3',4',6'-octa-O-acetyl-D-(+)-sucrose, gave 2,3,4,6-tetra-O-acetyl-${\beta}$-D-(+)-glucose and it suggests that the acetylated D-(+)-sucrose was rearranged through the formation of oxonium ion by mutarotation in the 2,3,4,6-tetra-O-acetyl-${\alpha}$-D-(+)-glucose moiety and through the ring opening in the 1',3',4',6'-tetra-O-acetyl-${\beta}$-D-(+)-fructose moiety.

• 분석과학
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• 제20권5호
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• pp.400-405
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• 2007

액체크로마토그래피/질량분석법(LC/MS) 및 핵자기공명분광분석법 $^1H(NMR)$을 이용하여 화장품에 들어있는 글리세린을 동시 비교분석하였다. 화장품 시료를 물에 용해시키고 수산화나트륨을 첨가하여 시료용액을 강알칼리 상태로 유지시킨 후, 시료용액 중의 글리세린을 benzoyl chloride로 유도체화 반응 시키고 유도체화된 글리세린을 pentane으로 추출하여 LC/MS로 정량분석 하였다. $^1H$ NMR 분석은 시료를 전처리 없이 $D_2O$ 용매에 직접 용해시키고, 글리세린을 ERETIC(Electronic REference To access In vivo Concentrations) 방법을 이용하여 $^1H$ NMR로 직접 정량분석 하였다. LC/MS 및 NMR 분석결과 LC/MS의 검량선은 $0.1-10{\mu}g/mL$ 농도범위에서 $r^2=0.9991$ 이었고 $^1H$ NMR의 검량선은 $25-500{\mu}g/mL$ 농도범위에서 $r^2=1$의 상관계수를 갖는 좋은 직선성을 얻었다.

• Natural Product Sciences
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• 제12권3호
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• pp.122-124
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• 2006

Three flavonoid glycosides, $kaempferol-3-O-{\alpha}-L-rhamnopyranosyl-(1\;{\rightarrow}\;6)-{\beta}$-D-glucopyranoside$ or kaempferol-3-O-rutinoside (1), $isorhamnetic-3-O-{\alpha}-L-rhamnopyranosyl-(16)-{\beta}-D-glucopyranoside$ or isorhamnetin-3-O-rutinoside (2), and $quercetin-3-O-{\beta}-D-glucopyranosyl-(1 ${\rightarrow}\;2)-{\beta}-L-arabinopyranoside$ 3, the latter one being a new compound, were isolated from the methanolic extract of the aerial parts of Carrichtera annua. Mass spectrometry and 1D and 2D NMR spectroscopy allowed establishing the structure of these compounds.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1187-1191
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• 2010

$^1H-^{15}N$ heteronuclear dipolar coupling solid-state NMR experiments on lipid bilayer or bicelle samples are very useful for the structural studies of membrane proteins. However, to study these biological samples using solid-state NMR, a specific probe with high efficiency and high capability is required. In this paper, we describe the optimized design, construction, and efficiency of a 400 MHz wide-bore $^1H-^{15}N$ solid-state NMR probe with 5-mm solenoidal rf coil for high power, multi-pulse sequence experiments, such as 2D PISEMA or 2D SAMMY.

• 한국자기공명학회논문지
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• 제5권1호
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• pp.29-36
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• 2001

The structures of two VBS (viral binding site) RNAs, SL1 and SL2, of Yeast Saccharomyces cerevisiae vims have been studied by 2D and 3D NMR experiments. VBSs play a crucial role in viral particle binding to the plus strand and packaging of the RNA. The secondary structures of the two VBS RNAs share a common feature of the stem-internal loop-stem-hairpin loop structure although the size of the internal loops of SL1 and SL2 differs. 2D experiments were sufficient for fill assignments of SL1. However, isotope labeling of the sample and multidimensional experiments were required for 28-nucleotide-long SL2 due to the spectral overlap. Several 3D HCCH experiments have accomplished full assignment of SL2 RNA.

• 한국자기공명학회논문지
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• 제23권4호
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• pp.87-92
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• 2019

Allium hookeri (Liliaceae) has been received the increasing attention as a bioactive resource due to its potent biological activities including anti-oxidant, anti-obesity, anti-microbial and lipid-regulating activities. The beneficial effects of A. hookeri are known contributed from the high content of organosulfur compounds in A. hookeri. Though a variety of articles demonstrated that A. hookeri contains 'saponin' as a bioactive constituent, the scientific evidence to prove it was limited. In the present study, we have attempted to identify saponin contained in A. hookeri through chromatographic isolation and NMR spectroscopic methods. As a result, a spirostane-type steroidal saponin (1) has been successfully isolated from the methanolic extract of A. hookeri roots. The structure of 1 was elucidated by extensive 1D and 2D spectroscopic methods including ¹H-NMR, ¹³C-NMR, ¹H-¹H COSY, HSQC, HMBC and NOESY; identified as (3β, 22R, 25S)-spirost-5-en-3yl O-6-deoxy-α-L-mannopyranosyl-(1→4)-O-6-deoxy-α-L-mannopyranosyl-(1→4)-O-[6-deoxy-α-L-mannopyranosyl-(1→2)]-β-D-gluco pyranoside. 1 showed the significant inhibitory activity on mushroom tyrosinase with IC₅₀ values of 248.7 μM while the inhibition on alpha-glucosidase was not significant.

• 한국자기공명학회논문지
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• 제15권2호
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• pp.128-136
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• 2011

A new sesterterpenoid, phorbaketal derivative, was isolated from the marine sponge Phorbas species. Its planar structures was completely determined from a combination of extensive 1D and 2D NMR experiments and MS data, and also the stereochemistry on the chiral centers were established by the ROESY experiment and the comparison with the $^1H$ and $^{13}C$ chemical shifts of the known phorbaketal compounds. This compound 1 moderately showed cytotoxicity effect against hepatoma cancer HepG2 cell.

• 한국지능시스템학회논문지
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• 제15권2호
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• pp.230-235
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• 2005

본 논문에서는 잡음에 열화된 대역에서 지능적으로 잡음의 패턴을 추정하여 지각 필터의 성능을 개선시켜 오디오 신호의 음질을 개선하는 알고리즘을 제안한다. 제안된 알고리즘은 묵음 구간에서 추정한 고정된 추정 잡음을 사용하는 기존의 방식을 사용하지 않고, 신호 구간마다 달라지는 신호의 세기와 잡음의 영향 정도를 고려하여 신호가 열세하고 잡음이 대부분을 차지하는 대역, 즉 잡음에 열화된 대역에서 잡음 패턴을 추정하여 신호를 열화시키는 잡음을 효과적으로 제어하는 방식으로 지각적으로 개선된 음질의 신호를 얻을 수 있다. 기존 방식과의 비교를 위해 다양한 신호 대 잡음 비(signal-to-noise ration, SNR)에서 열화된 오디오 신호를 입력으로 사용하였다. 입력 SNR이 $5\cal{dB},\;10\cal{dB},\;15\cal{dB}$와 $20\cal{dB}$의 각각의 경우에 대하여 객관적인 평가인 세그멘탈 신호 대 잡음비(Segmental SNR, SSNR)와 잡음 대 마스킹 비(Noise-to-mask ratio, NMR), 또한 주관적인 평가인 청감 테스트(Mean opinion score, MOS test)를 비교하였다. 그 결과, SSNR 측면에서는 각각의 경우에 대해 $7.4\cal{dB},\;6.8\cal{dB},\;5.7\cal{dB},\;5.1\cal{dB}$ 그리고, NMR 측면에서는 $15.7\cal{dB},\;15.5\cal{dB},\;15.2\cal{dB},\;14.8\cal{dB}$ 의 개선을 확인할 수 있었다. 또한 주관적인 측정 결과인 테스트의 개선 확인 및 음질 개선에 의한 성능을 확인할 수 있었다.

• 동의생리병리학회지
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• 제21권1호
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• pp.231-234
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• 2007

Dichlororinated bibenzyl compound (4) has been isolated from the New Zealand liverwort. This compound was elucidated using 1D/2D-NMR and mass spectral method. The compound (3) inhibited the growth of the Gram positive bacterium Bacillus subtilis ATCC 19659, (2 mm inhibition zone and 2 mm inhibition zone at 30 ${\mu}$g/disc), Candida albicans ATCC 14053, (2 mm inhibition zone and 2 mm inhibition zone at 30 ${\mu}$g/disc), and the dermatophytic fungi Trichophyton mentagrophytes ATCC 28185, (12 mm inhibition zone at 30 ${\mu}$g/disc) and Cladosporium resinae ATCC 52833 (2 mm inhibition zone at 30 ${\mu}$g/disc). This bibenzyl compound (4) exhibited antimicrobial activity.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2535-2541
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• 2009

Prebiotic isomaltooligosaccharide preparations contain $\alpha$-D-glucooligosaccharides comprising isomaltooligosaccharides (IMOs) and non-prebiotic maltooligosaccharides (MOs). They are both glucose oligosaccharides characterized by their degree of polymerization (DP) value (from 2 to $\sim$10), linkages types and positions (IMOs: $\alpha$-(1$\rightarrow$2, 3, 6 and in a lower proportion internal 1$\rightarrow$4) linkages, MOs: α-(1$\rightarrow$4) linkages). Their structure is the key factor for their prebiotic potential. In order to determine and elucidate the exact structure of unknown IMOs and MOs, unambiguous assignments of $^{13}C$ and $^1H$ chemical shifts of commercial standards, representative of IMOs and MOs diversity, have been determined using optimized standard one and two-dimensional experiments such as $^1H$ NMR, $^{13}C$ NMR, APT and ${^1}H-{^1}H$ COSY, TOCSY, NOESY and <$^1H-{^{13}}C$ heteronuclear HSQC, HSQC-TOCSY, and HMBC. Here we point out the differential effect of substitution by a glucose residue at different positions on chemical shifts of anomeric as well as ring carbons together with the effect of the reducing end configuration for low DP oligosaccharides and diasteroisotopic effect for H-6 protons. From this study, structural $^{13}C$ specific spectral features can be identified as tools for structural analysis of isomaltooligosaccharides.