• Macromolecular Research
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• v.15 no.7
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• pp.633-639
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• 2007

A variety of NMR techniques were applied to the micro-chemical structural characterization of polyanilines prepared via an efficient synthetic method in a self-stabilized dispersion medium in which the polymerization was conducted in a heterogeneous organic/aqueous biphasic system without any stabilizers. Here, the monomer and growing polymer chain were shown to function simultaneously as a stabilizer, imparting compatibility for the dispersion of the organic phase, and as a form of flexible template in an aqueous reaction medium. Polymerizations predicated on this concept generated polyanilines with a low defect content: solution state $^{13}C-NMR$ and solid $^{13}CDD/CP/MAS$ spectroscopy indicated that the synthesized HCPANi and its soluble derivative, HCPANi-t-BOC, evidenced distinctly different NMR spectra with fewer side peaks, as compared to conventionally prepared PANis, and the complete structural assignments of the observed NMR peaks could be determined via the combination of both 1D and 2D techniques. Ortho-linked defects in HCPANi were estimated to be as low as 7%, as shown by a comparison of the integration of the carbonyl carbon resonance peaks.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.325-330
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• 2000

Alginate obtained from brown algae had various physicochemical and rheological properties and could used as a dietary fiber, However, alginate has not been widely applied to the food industry, since it had high viscosity, high gelling effect conjugated with some mineral, and low solubility. To improve functionality of alginate, partially develymerized alginates, which was water-soluble dietary fiber were obtained by hydrolysis of alginate from the sea tangle, Laminaria japonicus, heated at $121^{\circ}C$. Effects of depolymerization of alginate on the changes of viscosity and average molecular weight, block composition ratio of mannuronate to guluronate (M/G ratio), chemical properties using $PT-IR, ^1H-NMR, and ^(13)C-NMR$ spectrum were investigated. The average molecular weight and viscosity of the alginate were rapidly decreased with the thermal decomposition, and estimated to be 1,307,415 dalton and 284,000 cps, before heating, 728,106 and 3,940.29 cps after 30 min heating, 102,635 and 22.22 cps after 2.5 hrs heating, 51,205 and 12.05 cps after 3 hrs, and 10,049 and 4.28 cps after 6.5 hrs, respectively. The M/G ratio was increased with the heating time, while MM-block did not show any changes and GG-block diminished. The results of $FT-IR, ^1H-NMR and ^(13)C-NMR$ spectrum suggested that changes of molecular structure did not occur by the thermal decomposition.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3248-3252
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• 2012

Vibrio extracellular metalloprotease (vEP), secreted from Vibrio vulnificus, shows various proteolytic function such as prothrombin activation and fibrinolytic activities. Premature form of vEP has an N-terminal (nPP) and a C-terminal (C-ter100) region. The nPP and C-ter100 regions are autocleaved for the matured metalloprotease activity. It has been proposed that two regions play a key role in regulating enzymatic activity of vEP. Especially, C-ter100 has a regulatory function on proteolytic activity of vEP. C-ter100 domain has been cloned into the E. coli expression vectors, pET32a and pGEX 4T-1 with TEV protease cleavage site and purified using gel-filtration chromatography followed by affinity chromatography. To understand how C-ter100 modulates proteolytic activity of vEP, structural studies were performed by heteronuclar multi-dimensional NMR spectroscopy. Backbone $^1H$, $^{15}N$ and $^{13}C$ resonances were assigned by data from standard triple resonance and HCCH-TOCSY experiments. The secondary structures of vEP C-ter100 were determined by TALOS+ and CSI software based on hydrogen/deuterium exchange. NMR data show that C-ter100 of vEP forms a ${\beta}$-barrel structure consisting of eight ${\beta}$-strands.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.123-129
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• 2005

Isolation and identification of pathogens from slaughter and meat processing plant were investigated. Antimicrobial activity of Amaranthus lividus against isolated pathogens such as Aeromonas sobria, Escherichia coli, Escherichia coli O157, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus was investigated. Among the chloroform, ethyl acetate and buthanol fraction of amaranthus lividus showed inhibitory effect against Aeromonas sobria CLFM1 and Escherichia coli CLFM2. Antimicrobial substance in chloroform fraction was isolated by silica gel adsorption column chromatography, sephadex LH-20 column chromatography and silica gel partition column chromatography. The antimicrobial compound of amaranthus lividus was identified as diethyl phtalate by HPLC, GC-MS, H-NMR and C-NMR.

• Archives of Pharmacal Research
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• v.20 no.5
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• pp.491-495
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• 1997

All fifteen flavonoids (1-15) have been isolated from the roots of Sophora flavescens (Leguminosae) as active principles of the cytotoxic property toward human tumor cell lines such as A549, SK-OV-3, SK-Mel-2, XF498 and HCT15, in vitro. By means of spectral analyses, particularlyby the aid of various two dimensional NMR experiments, all $^1H-NMR$ ad $^{13}C$ -NMR signals of 1-15 were completely assigned, and thus the structures of 1-15 were established unambiguously.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4021-4026
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• 2011

Functions of the luteinizing hormone releasing hormone (LHRH) and its induced release by divalent metal ions have received great attention because this neurotransmitter subsequently regulates the secretion of luteinizing hormone (LH). Metal-LHRH complexes were synthesized by addition of various Cu(II),Ni(II),Zn(II) ions into LHRH in order to understand how the induced release of LHRH is possible. The degree of complexation was monitored by $^1H$, $^{13}C$-NMR chemical shifts, and final products were identified by Mass spectrometry. Solutionstate structure determination of Zn(II)-LHRH out of metal-complexes was accomplished by using NMR and NMR-based distance geometry (DG). Interproton distance information from nuclear Overhauser effect spectroscopy was utilized for structure determination. Structure obtained in this study has a cyclic conformation exhibiting a specific ${\alpha}$-helical turn with residue numbers His[2]-Leu[7] out of 10 amino acids. Comparison of chemical shifts and EPR studies of Ni(II),Cu(II)-LHRH complexes exhibit that these metal complexes have 4-coordination geometry.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.655-659
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• 2006

Two dineolignans (1,2) with nitric oxide inhibitory activities were isolated from Saururus chinensis (Saururaceae) using silica gel column chromatography. Although the structures, saucernetin-7 (1) and -8 (2), have been already reported, NMR assignment of the two compounds was completed aided by 2D-NMR spectroscopy including $^1H-^1H$ COSY, $^1H-^{13}C$ COSY, HMBC and NOESY NMR spectra. Compounds 1 and 2 exhibited significant nitride oxide inhibitory activity in LPS-induced RAW 264.7 cells with $IC_{50}$ values of $11.3{\mu}M\;and\;7.1{\mu}M$, respectively.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.70-75
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• 2007

In the present study, we has been isolated the anti-cariogenic component, stigmasterol, from Aralia continentalis (A. continentalis) and identified by MS, $^1$H-NMR and $^{13}$C-NMR and also investigated the anti-cariogenic properties of stigmasterol. The methanol extract of ,A. continentalis showed concentration-dependent inhibitory activity against the growth and acid production of S. mutans. The MeOH extract was suspended in H$_2$O and sequentially partitioned with n-hexane, CHCl$_3$, EtOAc, and n-BuOH. The CHCl$_3$ fraction showed remarkable antibacterial activity against S. mutans. The anti-cariogenic compound, stigmasterol, has been isolated successively through the screening system and various chromatography methods. Anti-cariogenic properties of stigmasterol were also investigated. From this active chloroform subfraction, isolation and identification finally gave (24E)-stigmasta-5,22-dien-3${\beta}$-ol (stigmasterol) {[a]$_D\;^{25}$ -48.33$^{\circ}C$(C 0.28, CHCl$_3$)} by spectroscopic methods (MS, $^1$H-NMR and $^{13}$C-NMR) as an active principle. The compound, stigmasterol, showed significant growth, acid production, adhesion and water-insoluble glucan synthesis inhibitory effect against S. mutans. These results suggest that stigmasterol from ,A. continentalis may inhibit cariogenic properties of S. mutans and these properties may provide some scientific rationales that the local inhabitants used the extracts for treatment of dental diseases.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.129-133
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• 2004

The active compound responsible fer the anti-oxidant activity in Chinese cabbage kimchi were isolated and identified. The dichloromethane fraction of Chinese cabbage kimchi with the greatest anti-oxidant activity was used. Silica gel column chromatography, Sephadex LH-20 column chromatography, TLC, and Sep-pak catridge were used for isolating the active compounds and IR, EI-MS, GC-MS, $^{1}H-NMR$, $^{13}C-NMR$ were used to identify the structure of the isolated compounds. 3-(4'-Hydroxyl-3',5'-dimethoxyphenyl)propionic acid of molecular weight 226, which had 3.4 times greater free radical scavenging activity than Vit. C and significantly greater anti-oxidant activity against LDL oxidation than the control, was obtained, This active principle may be beneficial in preventing hyperlipidemia and artherosclerosis in human.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.679-684
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• 1992

New Pd(IV) complexes have been prepared through the reactions of $trans-[Pd(en)_2Cl_2](ClO_4)_2 $(en = ethylenediamine) with Guanine, Adenine, or Uracil anion as purine and pyrimidine base. We identified the ratio of central metal versus ligands by $C{\cdot}H{\cdot}N$ elemental analysis and proposed the coordinating site of the base by infrared spectrum, $^1H-NMR,\; and\; ^{13}C$-NMR spectrum. Guanine or Adenine ligand coordinated at N7 site and an en ligand exchanged for $ClO_4^-$ counter ions of the starting material . As these results, the complexes showed the formula $[Pd(en)L_2(ClO_4)_2](ClO_4)_2{\cdot}(en)$, (L = Guanine, Adenine). But in the Uracil complex no exchange of the en ligand and $ClO_4^-$ occured and Uracil anion preferred the N1 to N3 as coordinating site, the complex $[Pd(en)_2(Urac)_2](ClO_4)_2(Urac = Uracil anion).$