• Journal of the Korean Wood Science and Technology
• /
• v.25 no.2
• /
• pp.110-116
• /
• 1997

생강나무의 수피를 아세톤-물 (7:3)의 혼합용액으로 추출하여 에틸아세테이트용성과 수용성 화합물로 분리하였고 이중에서 에틸아세테이트용성 부분을 Sephadex LH-20과 TSK 40F로 충진한 칼럼크로마토그래피를 사용하여 5개의 화합물, 즉 (+)-catechin, (-)-epicatechin, quercetin 그리고 epicatechin-($4{\beta}{\rightarrow}6$-catechin 이량체와 epicatechin-($2{\beta}{\rightarrow}7$, $4{\beta}{\rightarrow}8$)-epicatechin 이량체를 단리 하였다. 단일물의 확인을 위하여 박층크로마토그래피를 실시하였으며, 화합물의 정확한 구조는 $^1H$-NMR과 $^{13}C$-NMR 스펙트럼을 이용하여 규명하였다.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.180-183
• /
• 2003

In this work. a potential inexpensive epoxy resin. epoxidized soybean oil (ESO) was synthesized and applied as a toughening agent for 4.4'-tetradiglycidyl diaminodiphenyl methane (TGDDM). The chemical structure of ESO was characterized by FT-IR, $^1H NMR, and ^{13}C NMR$ spectroscopy. The curing behaviors. thermal stabilities. fracture toughness. and flexural strength of TGDDM/ESO blend systems were investigated by using the dynamic DSC. thermogravimetric analysis (TGA). and flexural tests. The thermal stabilities of TGDDM/ESO blend systems were decreased with increasing ESO contents. whereas the critical stress intensity factor ($K_{IC}$) and flexural strength ($\sigma_f$) were increased with ESO contents up to 10 wt% ESO.

• Journal of Applied Biological Chemistry
• /
• v.42 no.4
• /
• pp.197-201
• /
• 1999

Antagonistic bacteria active against phytopathogenic fungi, Phytophthora capsici, Pythium ultimum, Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum were isolated from greenhouse soils. An antifungal compound was extracted by ethyl acetate from acidified culture filtrate and purified through column chromatography and thin layer chromatography. Activity-guided bioassay was followed throughout the purification steps using Pythium ultimum as a test organism. The purified antifungal compound was identified as phenylacetic acid (PAA) based on the data obtained from IR, EI/MS, $^1H-NMR$, and $^{13}C-NMR$. Two different isolates, which had vast differences in differential characteristics except 16S rDNA sequence homology, produced the same compound, phenylacetic acid. $ED_{50}$ values of the phenylacetic acid against P. ultimum, P. capsici, R. solani, B. cinerea, and F. oxysporum were 45, 21, 318, 360, and 226 ppm, respectively.

• Journal of the Korean Magnetic Resonance Society
• /
• v.13 no.2
• /
• pp.135-142
• /
• 2009

$^{195}Pt$ NMR measurements were performed to deduce the variation of local density of states at the Fermi energy ($E_F$-LDOS) at the surface of carbonsupported Pt catalysts due to the addition of $Nafion^{(R)}$ ionomer in the metalelectrode-assembly for fuel cells. The results showed that the EF-LDOS at the surface of Pt particles was enhanced by the addition of $Nafion^{(R)}$ ionomers whereas it was uninfluenced in the inner (bulk) part of the Pt particles. This suggests that the effects of ionomers on the electronic states of the Pt particle surface are related to the electrochemical activity of the catalysts.

• Journal of the Korean Magnetic Resonance Society
• /
• v.27 no.1
• /
• pp.1-4
• /
• 2023

Transthyretin (TTR) is an indispensable transporter protein of thyroxine and a retinol molecule in humans. TTR has a stable homo-tetrameric structure in its native state, while upon dissociation into monomers, it becomes aggregation-prone and can form an amyloid fibril. Although the amyloidogenic propensity of TTR has been known and investigated since the late 1990s, the structural information regarding TTR's amyloidogenic species is still elusive. Here, we employed high-pressure nuclear magnetic resonance (HP-NMR) approaches on the monomeric variant of TTR (TTR[F87M/L110M]; M-TTR) and observed that it experiences a two-step transition in response to the pressurized condition. Our study demonstrated that M-TTR in an ambient condition has heterogeneous structural features, which is likely related to the amyloidogenic propensity of TTR.

• Natural Product Sciences
• /
• v.29 no.1
• /
• pp.17-23
• /
• 2023

A phytochemical investigation of the fruits extract of Melia toosendan afforded the isolation of two new nor-neolignans, meliasendanins E (1) and F (2), as well as twelve known compounds (3 - 14) using various separation technique such as Diaion HP20, silica, RP-18 gel column chromatography and semi-preparative HPLC. Their chemical structures were elucidated by extensive NMR spectroscopic data including 2D-NMR, and HR-ESI-MS as well as ECD data. Among the twelve known compounds, the absolute structures of 3 - 6 were determined first, and given the trivial names as meliasendanins G-J (3 - 6). Based on the evaluation of anti-inflammatory activity, compounds 7 - 8 exhibited inhibitory effects on LPS-induced nitric oxide production in RAW 264.7 macrophages with IC₅₀ values of 34.6 and 39.5 µM, respectively.

• Journal of the Korean Magnetic Resonance Society
• /
• v.27 no.4
• /
• pp.23-27
• /
• 2023

Hoxc, or the Homeobox C cluster, is a group of genes that play a crucial role in embryonic development, particularly in patterning the body along the anterior-posterior axis. These genes encode transcription factors, which are proteins that bind to DNA and regulate the expression of other genes. Hoxc9 is specifically involved in the development of the skeletal system, nervous system, and adipose tissue. Hoxc9 overexpression has been linked to the development of various cancers such as leukemia and breast cancer. Here, we assigned the chemical shifts Hoxc9 DNA binding domain (DBD) using heteronuclear NMR techniques. The helical regions of Hoxc9 DBD correspond to the residues T200 - F213 (Helix I), T218 - L229 (Helix II), and T232 - K249 (Helix III). Our result would be helpful for studing the molecular interactions of the Hoxc9 DBD and other proteins.

• Natural Product Sciences
• /
• v.19 no.3
• /
• pp.206-214
• /
• 2013

The crocetin derivatives, crocin (1), gentiobiosyl glucosyl crocetin (3), and mono-gentiobiosyl crocetin (4) were isolated from the fruit of Gardenia jasminoides (Gj) and crocetin (2) from the processed fruit of Gj (PGj) by column chromatography. Their structures were determined on the basis of spectroscopic methods including IR, MS, and NMR (1D and 2D). These compounds were evaluated for their inhibition activity on melanin production in ${\alpha}$-MSH (melanocyte stimulating hormone) activated B16F10 cells. Compounds 1 - 4 reduced melanin content in a dose-dependent manner at concentrations of 20 - 60 uM. They also suppressed tyrosinase protein and m-RNA expressions dose dependently, assayed by western blot analysis, and RT-PCR experiment in B16F10 murine melanoma cells.

• Natural Product Sciences
• /
• v.19 no.3
• /
• pp.258-262
• /
• 2013

Three ergosterol derivatives, ergosta-4,6,8(14),22-tetraen-3-one (1), ergosta-7,24(28)-dien-3-ol (2), and 5,8-epidioxyergosta-6,22-dien-3-ol(3) were isolated from the fruit body of Phellinus pini. Their structures were based on spectroscopic methods including IR, MS, and NMR (1D and 2D). These compounds were evaluated for their activity to decrease melanin production in ${\alpha}$-MSH (melanocyte stimulating hormone) activated B16F10 cells. Compound 1, 2, and 3 reduced melanin content in a dose-dependent manner at concentrations of 5~15 uM. They also suppressed the tyrosinase expression of protein and m-RNA level dose dependently by western blot analysis and RT-PCR experiment in B16F10 murine melanoma cells.

• Journal of the Korean Wood Science and Technology
• /
• v.19 no.4
• /
• pp.73-79
• /
• 1991

The flavonoids from plants is very widly used as natural dye for food and medicine etc. In this study, red pine which is widespread in Korea was studied to find new chemicals which may use as raw material for the special purpose. The fIavonoids of red pine bark were separated with Sephadex LH-20 and Toyo pearl HW-40F as packed materials and the structure of separated f1avonoids was determined by $^1H$-and $^{13}C$-NMR spectroscopy. The (+) catechin which is widespread in nature and dihydroquercetin-3'-0-${\beta}$-galactoside were found in red pine bark. The dihydroquercetin-3'-0-${\beta}$-galactoside is newly found in this species.