• BMB Reports
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• v.43 no.6
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• pp.419-426
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• 2010

Aeromonas hydrophila is a bacterial pathogen that infects a large number of eukaryotes, including humans. The UDP-galactose 4'-epimerase (GalE) catalyzes interconversion of UDP-galactose to UDP-glucose and plays a key role in lipopolysaccharide biosynthesis. This makes it an important virulence determinant, and therefore a potential drug target. Our earlier studies revealed that unlike other GalEs, GalE of A. hydrophila exists as a monomer. This uniqueness necessitated elucidation of its structure and active site. Chemical modification of the 6xHis-rGalE demonstrated the role of histidine residue in catalysis and that it did not constitute the substrate binding pocket. Loss of the 6xHis-rGalE activity and coenzyme fluorescence with thiol modifying reagents established the role of two distinct vicinal thiols in catalysis. Chemical modification studies revealed arginine to be essential for catalysis. Site-directed mutagenesis indicated Tyr149 and Lys153 to be involved in catalysis. Use of glycerol as a cosolvent enhanced the GalE thermostability significantly.

• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.460-466
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• 2003

For the drug master file (DMF) of ketoconazole, four impurities (1-4) contained in ketoconazole were synthesized. During the synthesis of 2, a new synthetic method of 1,4-dihydropyrazine was established. To oxidize the aminoalcohol (2j) to the aminal (2j-1), the standard Swern oxidation condition was modified to mask the nucleophilicity of the amino group temporarily using one equivalent of acetic acid. Derivative 3 was synthesized via regioselective bromination at the 2 position of the 4-aminophenol derivative (3a) using $Br_2$ in the presence of p-TsOH. The etherification of aryl bromide with the phenol derivative (1f) was accomplished by a modification of the general Cu-mediated reaction condition using excess 1f itself as a solvent at elevated temperature (190 ℃).

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1293-1297
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• 2011

To improve the biological activities of rupestonic acid, 21 new rupestonic acid fatty ester derivatives (2a-2h) and aromatic ester derivatives (2i-2u) were synthesized and preliminarily evaluated for their anti-influenza activity in vitro by the national center for drug screening of China, using the Oseltamivir and Ribavirin as reference drugs. The results showed that 2l ($IC_{50}=0.5{\mu}mol/L$) exhibited potent anti-influenza $A_3$ viral activity among the synthesized compounds and was 10-fold more potent than that of the reference drug Oseltamivir ($IC_{50}=5.1{\mu}mol/L$).

• Korean Journal of Pharmacognosy
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• v.24 no.1
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• pp.69-77
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• 1993

Saikosaponins, originally isolated from Bupleuri Radix, were reported to exhibit diverse biological activities especially concerning with liver function. To elucidate the mode of protective action of saikosaponins on liver injury due to the acetaminophen administration, effects on drug metabolizing enzymes system and some transferase activities were checked. As the result, activities of transferase were shown to be strengthened by saikosaponin treatments significantly.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1303-1307
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• 2003

The low molecular water-soluble chitosan nanoparticles (LMWSC-NPs) were prepared, which was modified with hydrophilic and hydrophobic moieties to evaluate the potential for pharmaceutics application. The synthesis of LMWSC-NPs was identified by FT-IR and $^1H$-NMR spectra. Also, we measured the photon correlation spectroscopy (PCS), transmission electron microscope (TEM) and atomic force microscope (AFM) to investigate the characteristics and morphology of the LMWSC-NPs. At the PCS measurement, the more increase the number of substitutive group, the more decrease the positive charge of LMWSC-NP surface. From the results of TEM and AFM, spherical morphologies were observed, and their sizes were 30-150 nm. Resultantly, LMWSC-NPs prepared in this experiment will be expected as a suitable device for the drug targeting system.

• International journal of thyroidology
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• v.11 no.2
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• pp.71-74
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• 2018

Adverse events such as hemoptysis and gastrointestinal hemorrhage during tyrosine kinase inhibitor treatment are relatively rare, but the severity of the bleeding can be higher than other common adverse events. It is necessary to educate patients about its possibility so that they can be found early. In this case report of radioiodine refractory thyroid cancer patient, hemoptysis and gastrointestinal bleeding has occurred following lenvatinib administration. Drug interruption and dose modification and dose interruption were required in addition to management for bleeding itself. It is necessary to confirm the high risk of bleeding before the administration of tyrosine kinase inhibitors, and to appropriately control the follow-up interval and drug dosage accordingly.

• BMB Reports
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• v.49 no.11
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• pp.585-586
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• 2016

Extracellular vesicles (EVs) are natural carriers of biomolecules that play central roles in cell-to-cell communications. Based on this, there have been various attempts to use EVs as therapeutic drug carriers. From chemical reagents to nucleic acids, various macromolecules were successfully loaded into EVs; however, loading of proteins with high molecular weight has been huddled with several problems. Purification of recombinant proteins is expensive and time consuming, and easily results in modification of proteins due to physical or chemical forces. Also, the loading efficiency of conventional methods is too low for most proteins. We have recently proposed a new method, the so-called exosomes for protein loading via optically reversible protein-protein interaction (EXPLORs), to overcome the limitations. Since EXPLORs are produced by actively loading of intracellular proteins into EVs using blue light without protein purification steps, we demonstrated that the EXPLOR technique significantly improves the loading and delivery efficiency of therapeutic proteins. In further in vitro and in vivo experiments, we demonstrate the potential of EXPLOR technology as a novel platform for biopharmaceuticals, by successful delivery of several functional proteins such as Cre recombinase, into the target cells.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.287-295
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• 2017

Using nanotechnology, magnetic nanoparticles of iron oxide were produced via co-precipitation method and followed modification with organic compounds. In the next step, functionalized monomer was provided via coupling ${\beta}$-cyclodextrine and allylamine onto modified magnetic nanoparticles. These nanoparticles were used to establish the adsorption rate of celecoxib. Magnetic nanoparticles are modified by (3-mercaptopropyl)trimethoxysilane. Nano-adsorbent was characterized by analytical and spectroscopic methods, such as Fourier transform infrared spectroscopy, elemental analysis, thermo-gravimetric analysis, and transmission electron microscopy (TEM). Laboratory parameters, such as the kinetics of adsorption isotherms, pH, reaction temperature and capacity were optimized. Finally, by using this nano-adsorbent in the optimized condition, extraction of celecoxib from biological samples as urine, drug matrix and blood plasma was carried out by high performance liquid chromatography with sensitivity and high accuracy.

• YAKHAK HOEJI
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• v.46 no.3
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• pp.155-160
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• 2002

Through a modification of allicin structure a disagreeable odor and chemical instability of allicin can be improved. 3-Alkoxy-6-allylthiopyridazine derivatives exhibit a superior effect for prevention and treatment of hepatic diseases induced by carbon tetrachloride and aflatoxin B1 and for prevention of human tissues from radiation. These compounds inhibit also efficiently SK-Hep-1 cell proliferation through induction of apoptosis. So another 4,5-mono- or di-substituted 3-alkyloxy-6-allylthiopyridazine derivatives were synthesized on purpose to find out SAR of allylthiopyridazine in hepatoprotective and hepatotherapeutic acitivitis and to develop more effective drug candidate.

• KSBB Journal
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• v.16 no.5
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• pp.505-510
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• 2001

The preparation, characterization and drug release behaviour of drug(indomethacin) loaded Poly(L-lactic acid)(PLA), tarmarind acetate and levan acetate mircospheres were investigated. Hydrophobic tarmarind acetate and levan acetate were prepared by chemical modification of hydrophilic tarmaried gum and levan and microspheres were made by a solvent evaporation method. In the case of poly(L-lactic acid) microspheres, drug release rate was effected by polymer-drug ratios and drum release was sustained by increasing of polymer content. The yield of microspheres were effected by many factors and the mean size was below 1 $\mu$m, The IND release profiles from tarmarind acetate and levan acetate micropheres were more slightly less than ploy(L-lactic acid) microspheres.