• 한국자기공명학회논문지
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• 제12권2호
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• pp.81-88
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• 2008

Solid HETCOR (Hetero-Correlation) requires homo-dipolar decoupling between proton spins during the evolution and the mixing period in 2D-NMR. There are two different ways of achieving it with pulse sequences. One is based on the multiple pulse (MP) sequence where thousands of intense radio frequency (rf) pulses are used to remove the homo-dipolar interaction between protons. The other is utilizing the so-called Lee-Goldburg (LG) off-resonance scheme where a continuous rf-irradiation is used. In this report, the advantage of one technique to the other, is analyzed. LG version is evaluated better in S/N and easier in setup procedure with the same experimental time.

• Archives of Pharmacal Research
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• 제19권4호
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• pp.302-306
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• 1996

The $^1H- and^{13}C-NMR$ spectra of alaternin, aurantio-obtusin, chryso-obtusin, obtusin and 2-glucosyl obtusifolin isolated from the seeds of Cassia tora have been assigned based on HMBC, long-range HETCOR, fully $^1H-coupled {13}^C-NMR$, deuterium isotope experiment, and by comparison with the model compounds.

• Bulletin of the Korean Chemical Society
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• 제13권1호
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• pp.87-91
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• 1992

The structures of the compounds, 1, 2, 3, and 4, which were precursors of analgesics, were confirmed by modern NMR techniques. The complete $^{13}C-NMR$ assignments of these systems were established by applying COLOC (COrrelated spectroscopy for LOng range Couplings), HETCOR (HETeronuclear CORrelated spectroscopy), RCT (Relay Coherence Transfer), and NOE difference spectroscopy. The limitation of COLOC approach which has been widely used recently is discussed.

• Journal of the Korean Wood Science and Technology
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• 제34권4호
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• pp.76-82
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• 2006

화백나무(Chamaecyparis pisifera (Sieb. et Zucc.) Endlicher) 잎을 채취하여 건조시킨 후 분쇄하여 2.0 kg을 acetone-$H_2O$ (7:3, v/v)로 추출하고 헥산, 메틸렌클로라이드, 에틸아세테이트 및 수용성으로 분획하여 동결건조시켰다. 에틸아세테이트용성 분획을 sephadex LH-20으로 충진한 칼럼에서 메탄올과 에탄올-헥산 혼합액을 용리용매로 사용하여 칼럼크로마토그래피를 실시하였다. 단리된 화합물들은 TLC로 확인한 후 $^1H$-, $^{13}C$-NMR, COSY, HETCOR 등의 스펙트럼을 사용하여 정확한 구조를 규명하였고 FAB-MS로써 분자량을 측정하였다. 화백나무 잎의 에틸아세테이트 가용부에는 (+)-catechin (화합물 I), taxifolin-3-O-${\beta}$-D-xylopyranoside (화합물 II), quercetin-3-O-${\alpha}$-L-rhamnopyranoside (화합물 III)가 분리되었으며 단리 화합물에 대한 항산화 실험에서는 화합물 모두 기준물질과 유사한 높은 항산화 활성을 나타내었다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.89-94
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• 1998

Marine sponges are recognized as a plentiful source of diverse biologically active secondary metabolites. Recently, we have initiated a research to discover antitumor constituents from the marine sponges collected from Korean Waters. Marine sponges collected from the South Sea of Korea were screened for several biological activities including such as brine shrimp lethality and cytotoxicity. Significant brine shrimp lethality was detected in the crude extract of a two-sponge association of Poecillastra sp. and Jaspis sp. A cross-section of this sample showed two layers of morphologically distinct sponges. The thin and dirty yellow outer layer was identified as Poecillastra sp. (Pachastrellidae), the surface of which was very rough. The light-grey inner layer was identified as Jaspis sp. (Jaspidae), the surface of which was smooth. This two-sponge association appears to be consistent as these sponges were always found in associated form regardless of collection site or collection period. Investigation of the bioactive constituents monitored by brine shrimp lethality assay led to the isolation of pectenotoxin II (PTX2) and psammaplin A as causative compounds for the brine shrimp lethality. $^1$H- and $\^$13/C-nmr signals of PTX2 was fully assigned utilizing TOCSY, HETCOR, Long-range HETCOR, and Homonuclear J-resolved 2D experiments. PTX2 displayed very potent and selective cytotoxicities in the 60 cell line panel antitumor assay at the NCI. PTX2 has progressed to acute toxicity determination and in vivo antitumor assay at the NCI (Table 1). However, significant in vitro antitumor activity of PTX2 can not be affirmed in the in vivo assay.

• Natural Product Sciences
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• 제2권2호
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• pp.106-114
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• 1996

Four polymethoxyfavones were isolated from the leaves of Citrus deliciosa, three of which (nobiletin, 5-O-demethylnobiletin, and tangeritin) are bioactive. The fourth (7,4'-dihydroxy-5,6,8,3'-tetramethoxyflavone) is reported for the first time in the genus Citrus and is a potential chemotaxonomic marker. The structures of these flavones were confirmed by analysing their spectral data and comparison with similar compounds. The previously reported $^{13}C$ NMR assignment of 5-O-demethylnobiletin has been revised on the basis of 2D NMR experiments (HETCOR, COSY, and COLOC). The chemotaxonomic value of the present finding is verified.

• Journal of the Korean Wood Science and Technology
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• 제34권3호
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• pp.73-83
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• 2006

구상나무(Abies koreana Maximowicz)와 전나무(Abies holophylla Wilson) 잎을 채취하여 건조시킨 후 분말로 제조하여 각각 1.5 kg을 아세톤-물(7:3, v/v)로 추출하고 헥산, 메틸렌클로라이드, 에틸아세테이트 및 수용성으로 분획하여 동결건조 시켰다. 에틸아세테이트용성 분획을 Sephadex LH-20으로 충진한 칼럼에서 메탄올과 에탄올-헥산 혼합액을 용리용매로 사용하여 칼럼크로마토그래피를 실시하였다. 단리된 화합물들은 TLC로 확인한 후 $^1H-$, $^{13}C-NMR$, COSY, HETCOR 등의 스펙트럼을 사용하여 정확한 구조를 규명하였고 FAB 및 EI-MS로써 분자량을 측정하였다. 많은 양의 aromadendrin-7-O-${\beta}$-D-glucopyranoside (화합물 III), polydatin (화합물 VI), (-)-rhododendrol-2-O-${\beta}$-D-glucopyranoside (화합물 VII)가 단리되었으며, 소량의 (+)-catechin (화합물 I), kaempferol-3-O-${\beta}$-D-glucopyranoside (화합물IV), myricetin-3-O-${\beta}$-D-glucopyranoside (화합물 V), naringenin-7-O-${\beta}$-D-glucopyranoside (화합물 II)도 단리 되었다. DPPH 라디칼 소거법을 이용하여 단리된 화합물들에 대한 항산화 활성시험을 실시하였으며 (+)- catechin과 polydatin이 항산화 효능을 나타내었다.

• 한국자기공명학회논문지
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• 제10권1호
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• pp.115-125
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• 2006

Hippuryl-L-histidyl-L-leucine(HHL) is widely used as a substrate of angiotensin converting enzyme(ACE) cleaving the neurotransmitter angiotensin(I) to the octapeptide angiotensin(II). The structure of the substrate molecules should provide information regarding the geometric requirements of the ACE active site. For the purpose of determination of in vivo reaction, metallo(Cu, Zn)-HHL complexes were synthesized and the degree of complex formation were identified by MALDITOF, ESI mass spectrometric analysis. Tn addition, the pH-dependent species distribution curves were obtained by potentiometric titration. Nitrogen atoms of imidazole ring and oxygen atom of caboxylate groups in the peptide chain were observed to be participated in the metal complex formation. After purification of complexes further structural characterization were made by utilizing UV-Vis, electrochemical methods and NMR. Complete NMR signal assignments were carried out by using 2D-spectrum techniques COSY, TOCSY, NOESY, HETCOR. A complex that two imidazole and carboxylate groups are asymmetrically participating to coordination mode was predicted to the solution-state structure of $Cu(II)-HHL_2$ based on $^{13}C-NMR$ signal assignment and NOE information.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.93-98
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• 2006

Two new compounds 1'-(stigmast-11,20(21),25-trien 3$\alpha$,9$\alpha$-diolyl)-3'-(pimara-11,15-dien-3$\alpha$-olyl) glycerol (1) and stigmast-5-en-3$\alpha$,26-diol (2) along with known fatty acids n-hexacosanoic acid (3) and hexadecanoic acid (4), have been isolated from the methanol extract of rice hulls of Oryza sativa. The structures of the compounds were elucidated using 1D and 2D NMR spectral methods, viz; $^1H, ^{13}C, ^{13}C$-DEPT, $^1H-^1H$ COSY, $^1H-^{13}C$ HETCOR, HSQC and HMBC aided by IR, EIMS, FABMS and HRFABMS. Compound (1) showed inhibition to radish germination, growth of shoot and root length.