• 대한화학회지
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• 제35권3호
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• pp.196-203
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• 1991

25$^{\circ}$C 때 벤조산과 메타 및 파라위치에 할로겐(F, Cl, Br)이 치환된 $pK_a$값을 메탄올-물 혼합용매(0∼80% 메탄올) 중에서 Fuoss-Kraus 식에 근거한 전도도법과 Gelb의 전도도법을 이용하여 결정하였다. 할로겐 치환기에 따른 벤조산의 $pK_a$ 변화를 전자받게 유도효과와 전자주게 공명효과로 복합시킨 치환기 상수(${\sigma}_1$ 및 ${\sigma}_R$)로써 논의하였다. ${\sigma}_1$가 $D^{-1}$에 대하여 양(+)의 기울기를 갖는 직선성을 보인 반면 ${\sigma}_R$은 $D^{-1}$에 대하여 음(-)의 기울기를 갖는 직선성을 보이고 있는데, 이를 field effect의 유전상수 의존성과 할로겐 치환기의 ${\pi}$-고립쌍 전자와 이온화 중심간의 through-space ${\pi}$-상호작용으로 해석하였다.

• 생명과학회지
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• 제11권1호
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• pp.93-96
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• 2001

n-BuOH fraction obtained from MeOH extracts of Allium monanthum was applied to repeated silica gel column chromatographies to give a glycosylglyceride. The chemical structure of the compound was determined to be 1-O-linolenoyl-2-O-linolenoyl-3-O-$\beta$-D-galactopyranosyl-누-glycerol on the basis of NMR data and by the adaptation of chemical methods.

• 생약학회지
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• 제38권4호
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• pp.358-362
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• 2007

From the EtOAc fraction of the MeOH extract of Ulmus davidiana, (-)-catechin (1), (-)-catechin-7-O-${\beta}$-D-apiofuranoside (2), and (-)-catechin-7-O-${\beta}$-D-xylopyranoside (3) were isolated and characterized on the basis of $^1H-and\;^{13}C-NMR$, and FABMS spectral data. Compounds 1-3 showed more strong reducing power activities than ${\alpha}-tocopherol$, a positive control.

• Natural Product Sciences
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• 제6권3호
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• pp.135-138
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• 2000

MeOH extract of Cuscuta chinensis seeds was fractionated with n-hexane, EtOAc and BuOH successively, and antioxidant activities were tested for all fractions using DPPH free radical scavenging method. In the tested fractions, EtOAc fraction showed high antioxidant activity$(EC_{50},\;50\;{\mu}g)$ From the EtOAc fraction, five compounds have been isolated. On the basis of spectral data, these compounds were identified as ${\beta}-sitosterol$, methyl 4-hydroxy-3,5-dimethoxycinnamate, ${\beta}-sitosterol-3-O-{\beta}-D-glucopyranoside$, caffeic acid, quercetin, kaempferol and calycopteretin. Among these compounds, ${\beta}-sitosterol$ and ${\beta}-sitosterol-3-O-{\beta}-D-glucopyranoside$ showed no antioxidant activity. $EC_{50}$ values of methyl 4-hydroxy-3,5-dimethoxycinnamate, caffeic acid, quercetin, kaempferol and calycopteretin were 0.6, 8, 19, 17 and $12\;{\mu}g$, respectively.

• Journal of the Korean Wood Science and Technology
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• 제31권2호
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• pp.45-51
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• 2003

큰잎자작 변재의 메탄올(methanol, MeOH) 조추출물로부터 silica gel column, CPC 등의 크로마토그라피를 이용하여 4종의 화합물을 단리하였으며, 단리물질에 대한 NMR 등의 기기분석 결과, flavonoid 및 lignan 배당체인 catechin 7-O-𝛽-D-xylopyranoside, lyoniresinol 9'-O-𝛽-D-glucopyranoside, 그리고 diarylheptanoid인 11-oxo-3, 8, 12, 17-tetrahydroxy-9-ene [7, 0]-metacyclophane 및 11-oxo-3, 8, 9, 10, 12, 17-hexahydroxy [7, 0]-metacyclophane으로 각각 동정하였다.

• Archives of Pharmacal Research
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• 제17권5호
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• pp.314-317
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• 1994

The studies were camied out to evaluate the constituents in the leaves of Crataegus pinnatifida var. psilosa (Rosaceae) continuously. From the BuOH fraction of the MeOH extract, four flavonoid compounds, hyperoside (1), vitexin (2), 3"-O-rhamnosylvitexin (3) and $quercetin-3-O-{\alpha}-L-rhamnopyranoslyl-(1{\rightarrow}6)-{\beta}$-D-galactopyranoside (4) were isolated and identified on the basis of their physico-chemical properties and spectroscopic evidences by comparison with authentic samples.

• Archives of Pharmacal Research
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• 제20권3호
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• pp.280-282
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• 1997

A genuine dammarane-glycoside, named as ginsenoside $ Rs_3$, was isolated from the MeOH extracts of Korean red ginseng (Panax ginseng C.A. Meyer) through repeated silica gel column chromatographies and its chemical structure was determined as (20S)-protopanaxadiol $3-O-[6^{11}-O-acetyl-{\beta}-D-glucopyranosyl (1{\rightarrow2)-{\beta}-D-$glucopyranoside on the basis of several spectral and physical evidences including HMBC and FAB-MS.

• Journal of Forest and Environmental Science
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• 제23권1호
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• pp.1-4
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• 2007

The bark of Juglans mandshurica Maxim. was collected, extracted with acetone-$H_2O$ (7:3, v/v), fractioned with n-hexane, $CH_2Cl_2$ and EtOAc, then each fraction was freeze-dried to give some powders. A portion of the EtOAc (28.4 g) fraction was chromatographed on a Sephadex LH-20 column eluting with a series of MeOH-$H_2O$ and EtOH-hexane mixture. Four gallotannins, gallic acid (1), ellagic acid (2), 1,2,4,6-tetra-O-galloyl-${\beta}$-D-glucose (3) and 1,2,3,4,6-penta-O-galloyl-${\beta}$-D-glucose (4), have been isolated from the EtOAc fraction Their structures were elucidated on the basis of chemical evidence and spectrometric analysis such as NMR and MS. The antioxidant activities on each fraction and the isolated gallotannins were evaluated by DPPH radical scavenging test.

• Journal of Applied Biological Chemistry
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• 제59권2호
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• pp.103-106
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• 2016

가지 잎으로부터 3종의 phenylpropanoid, 1종의 flavonoid glycoside, 그리고 1종의 norsesquiterpenoid glycoside 화합물을 분리 동정하였다. 가지 잎을 80 % MeOH로 추출하였으며, 얻어진 추출물을 n-hexane, EtOAc, n-BuOH 및 물 층으로 계통분획을 실시하였다. 이 중 n-BuOH 분획에 대하여 $SiO_2$, ODS 및 Sephadex LH-20 column chromatography를 반복 실시하여 5종의 화합물을 분리, 정제하였다. Nuclear magnetic resonance, infrared spectroscopy 및 mass spectrometry의 spectroscopic data를 해석하여 이 화합물들을 caffeic acid (1), chlorogenic acid (2), cryptochlorogenic acid (3), panasenoside (4), 및 (6R,7E,9R)-4,7-megastigmadien-3-one-9-${\beta}$-${\small{D}}$-glucopyranoside (5) 로 각각 동정하였다. 본 연구에서 화합물 3과 4는 가지 잎에서 처음으로 분리, 동정하였다.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3880-3886
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• 2011

The nucleophilic substitution reactions of diisopropyl thiophophinic chloride (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $65.0^{\circ}C$. The anilinolysis rate of 3 is rather slow to be rationalized by the conventional stereoelectronic effects. The obtained deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are secondary inverse ($k_H/k_D$ = 0.80-0.96). The anilinolyses of ten P=S systems in MeCN are reviewed on the basis of DKIEs and selectivity parameters to obtain systematic information on the DKIEs and mechanism for thiophosphoryl transfer reactions. The steric effects of the two ligands on reactivity, DKIEs, mechanism, and substituent effects of the nucleophile (X) on the DKIEs are discussed.