• 생약학회지
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• 제21권2호
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• pp.148-152
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• 1990

Seven flavonol glycosides from the EtOAc fraction of Ginkgo biloba leaves were identified by high performance liquid chromatography. Separation by reversed phase chromatography on $Lichrosorb^{\circledR}$ RP-18 column was achieved by isocratic elution. The content of the major acylated flavonol glycoside, kaempferol 3-0-[$6'-O-{p}-coumaroyl-{\beta}-_D-glucosyl(1{\rightarrow}2)-{\alpha}-_L-rhamnoside$] was about 8.0% and 0.55% for EtOAc fraction and MeOH extract, respectively.

• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1661-1677
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• 2006

Rhizobium and related genera are soil bacteria with great metabolic plasticity. These microorganisms survive in many different environments and are capable of eliciting the formation of nitrogen-fixing nodules on legumes. The successful establishment of symbiosis is precisely regulated and requires a series of signal exchanges between the two partners. Quorum sensing (QS) is a prevalent form of population density-dependent gene regulation. Recently, increasing evidence indicates that rhizobial quorum sensing provides a pervasive regulatory network, which plays a more generalized role in the physiological activity of free-living rhizobia, as well as during symbiosis. Several rhizobia utilize multiple, overlapping quorum sensing systems to regulate diverse properties, including conjugal transfer and copy number control of plasmids, exopolysaccharide biosynthesis, rhizosphere-related functions, and cell growth. Genomic and proteomic analyses have begun to reveal the wide range of functions under quorum-sensing control.

• 한국미생물·생명공학회지
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• 제32권1호
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• pp.1-10
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• 2004

Many bacteria monitor their population density and control the expression of specialized gene sets in response to bacterial cell density based on a mechanism referred to as quorum sensing. In all cases, quorum sensing involves the production and detection of extracellular signaling molecules, auto inducers, as which Gram-negative and Gram-positive bacteria use most prevalently acylated homoserine lactones and processed oligo-peptides, respectively. Through quorum-sensing communication circuits, bacteria regulate a diverse array of physiological functions, including virulence, symbiosis, competence, conjugation, antibiotic production, motility, sporulation, and biofilm formation. Many pathogens have evolved quorum-sensing mechanisms to mount population-density-dependent attacks to over-whelm the defense responses of plants, animals, and humans. Since these AHL-mediated signaling mechanisms are widespread and highly conserved in many pathogenic bacteria, the disruption of quorum-sensing system might be an attractive target for novel anti-infective therapy. To control AHL-mediated pathogenicity, several promising strategies to disrupt bacterial quorum sensing have been reported, and several chemicals and enzymes have been also investigated for years. These studies indicate that anti-quorum sensing strategies could be developed as possible alternatives of antibiotics.

• 약학회지
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• 제34권2호
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• pp.80-87
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• 1990

3-Substituted 5-aminoisoxazole-4-carboxylates were prepared by the reaction of corresponding bormoaldoximes with cyanoacetate. The 3-trifluoromethylisoxazole derivatives were acylated to amides with various aminopyridine derivatives to afford diamides. The ester group was hydrolyzed and decarboxylated easily to give 3-trifluoromethyl-5-aminoisoxazole. The aminoisoxazole was also converted to amides. 5-Amino-3-trifluoromethylisoxazole-5-one-4-carboxylate was prepared by the reaction of trifluoroacetoaldoximoyl bromide and malonate. 5-Amino-3-methylisoxazole-5-one-4-acetate was prepared by the reaction of hydroxylamine and acetylmalonate. The synthesized compounds were tested for antiinflammatory activities.

• 대한화학회지
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• 제58권6호
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• pp.569-574
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• 2014

The synthesis of O-desmethylangolensin (O-DMA) analogues from methoxy-substituted benzoic acids was described. Treatment of methoxy-substituted benzoic acids with 2 equiv of ethyllithium afforded methoxypropiophenones, which were subsequently transformed to ethyl 2-(methoxyphenyl)propionates via 1,2-rearrangement of the methoxyphenyl group using $Pb(OAc)_4/HClO_4$ in triethyl orthoformate. After hydrolysis with KOH, the 2-(methoxyphenyl)propionic acids were reacted with di-2-pyridyl carbonate to afford 2-pyridyl 2-(methoxyphenyl)propionates, which were acylated with methoxy-substituted phenylmagnesium bromides to give methoxy-${\alpha}$-methyldesoxybenzoins. The methoxy groups of these compounds were selectively or fully demethylated using boron tribromide to give diverse O-DMA analogues in high yields.

• 한국염색가공학회지
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• 제7권1호
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• pp.65-71
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• 1995

Wool yarns were treated in dimethylformamide solutions containing various concentrations of three dibasic acid anhydrides : succinic, itaconic, and phthalic anhydrides in various conditions. The structural aspects of these dibasic acid anhydrides are different : the succinic, itaconic, and phthalic acid anhydrides have saturated aliphatic etylene, unsaturated aliphatic vinyl and aromatic phenyl groups, respectively. The reaction mechanism of the acylation of wool keratin and some resction conditions were invastigated. And the results are as follows. 1. The N-acylation and formation of free carboxyl group were dominant rather than the O-acylation cross-linked on the side chain of polypeptide. The acylation of wool keratin is easier than that of silk fibroin. 2. The higher molecular weight, steric hinderance and resonance caused lower acylating reactivity. By the determination of acyl contents for acylated keratin, it was rerealed that the degree of acylation was succinic acid anhydride > itaconic acid anhhydride > phthalic acid anhydride.

• 생약학회지
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• 제7권1호
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• pp.51-54
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• 1976

Steroid and terpenoid constituents of 3 species of genus Phytolacca have been examined by TLC. All contained ${\alpha}$-spinasterol, its glucoside and acylated glucoside, jaligonic acid and its methylester, esculentic acid and its methylester, and 10 phytolaccosides. Jaligonic acid was the major free triterpenoid and phytolaccoside E was the major saponin in all plants. Bayogenin, oleanolic acid, spergulagenic acid, acinosolic acid, hederogenin, and their derivatives contained in other Phytolacca spp. were not found in these plants.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.411-414
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• 2002

Acylated homoserine lactones (AHLs) are membrane-permeant signal molecules responsible for biofilm formation of gram-negative bacteria via a unique mechanism known as quorum sensing. A target specific bioassay employing the AHL-responsive Agrobacterium tumefaciens reporter strain has been developed to identify new AHL-like compounds from natural products, which could be developed into antifouling compounds. By varying the X-gal concentration, incubation time, solvent for sample preparation and the sample loading procedure, it was possible to detect low level AHLs up to $10^1nM$. The length of the acyl chain of the AHLs was found to affect the sensitivity of this bioassay.

• 한국식생활문화학회지
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• 제14권5호
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• pp.467-476
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• 1999

We studied to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Soybean protein isolate was acylated rapidly up to 80% modification and more of 80% modification was proceed slowly. Electrophoretic analysis showed that more changes in modified protein. Also, modification of soybean protein produced more ionizable tyrosines and exposed more hydrophobic groups, while modified protein exhibited a loss of reactive sulfhydryl groups. Spectrophoretic studies demonstrated that the shift was occurred at the UV 278nm and fluorescence 333nm, respectively, and the intensity decreased as the degree of modification was increased.

• Journal of Applied Biological Chemistry
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• 제43권2호
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• pp.79-85
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• 2000

Biodegradable films were prepared from roasted sesame meal and rice bran. Acetic anhydride, succinic anhydride, and formaldehyde were added to the film-forming solutions, and their effects on tensile strength, percent elongation, water vapor permeability, and water solubility of the films were studied. Roasted sesame meal did not form film without acylation or addition of formaldehyde. Acylated roasted sesame films had higher tensile strength and water-solubility, and lower % elongation than rice bran films. Acylation with acetic and succinic anhydrides increased tensile strength, percent elongation, and water solubility of rice bran films, but decreased water vapor permeability. Treatment with formaldehyde increased tensile strength of roasted sesame and rice bran films and % elongation of rice bran films, while reducing water-solubility of roasted sesame and rice bran films and water vapor permeability of rice bran films.