• Korean Journal of Pharmacognosy
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• v.30 no.4
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• pp.397-403
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• 1999

Tyrosinase plays an important role in the process of melanin polymer biosynthesis. Therefore, the enzyme inhibitors have been of great concern as cosmetics to have skin-whitening effects on the local hyperpigmentation. During the search for new inhibitory compounds on melanin polymer biosynthesis from natural sources, MeOH extracts of 589 higher plants were tested for the inhibitory effect on tyrosinase activity by the muschroom tyrosinase assay in vitro. Among plants tested, the leaves of Cercis chinensis exhibited potent inhibitory effect on mushroom tyrosinase activity. Subsequently seven active compounds were isolated from the ethyl acetate soluble part of acetone extract of the leaves of C. chinensis by the activity guided fractionation monitoring the inhibitory effect on tyrosinase activity. Their chemical structures were identified as $kaempferol-3-0-{\alpha}-L-rhamnoside$, quercitrin, $myricetin-3-0-{\alpha}-L-rhamnoside$, myricetin-3-0-(2'-O-galloyl)- ${\alpha}$ -L-rhamopyranoside (desmanthin), (-)-epicatechin-3-0-gallate, (-)-epigallocatechin-3-0-gallate, and methyl gallate on the basis of the speculation of spectral data and chemical reaction. Among the flavonol rhamnosides, myricetin-3-0-(2'-O-galloyl)- -L-rhamnoside(desmanthin) showed most potent inhibitory effect on tyrosinase activity and the structure of B-ring in flavonol moiety was related to the activity. (-)-Epigallocatechin-3-O-gallate having pyrogallol group in flavan-3-ol moiety exhibited more potent inhibitory effect than (-)-epicatechin-3-0-gallate having catechol group in flavan-3-ol moiety on mushroom tyrosinase activity.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.220.2-220.2
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• 2011

Biodiesel and biodiesel blend fuel are receiving increasing attention as alternative fuels for diesel engines without substantial modifications. Biodiesel fuels and blending have been widely studied and applied in diesel engine because of biodiesel's lower sulfur, lower aromatic hydrocarbon and higher oxygen content. Biodiesels have the potential to be oxidized in different condition. It has reported that oxidation deterioration of biodiesel is different in the condition of storage and oxidation causes chemical property change of methyl esters. Sunlight intensity, temperature, material of container and contact surface with oxygen are key dominant factors accelerating oxidation deterioration. In this study, we chose temperature among key oxidation conditions and metal container filled with biodiesel was heated at about $110^{\circ}C$ for 10 days in order to accelerate oxidation deterioration. To better understand the effect of biodiesel blends on emission, steady state tests were conducted on a heavy duty diesel engine. The engine was fueled with Ultra Low Sulphur Diesel(ULSD), a blend of 10% and 20%(BD10, BD20) on volumetric basis, equipped with a common rail direct injection system and turbocharger, lives up to the requirements of EURO 3. The experimental results show that the blend fuel of normal biodiesel with BD10 and BD20 increased NOx. The result of PM was similar to diesel fuel on BD10, but the result of PM on BD20 was increased about 63% more than its of diesel. The blend fuel of Oxidation biodiesel with BD10 and BD20 increased NOx as the results of normal biodiesel. But PM was all increased on BD10 and BD20. Especially THC was extremely increased when test fuel contains biodiesel about 140% more than its of diesel. Through this study, we knew that oxidation deterioration of biodiesel affects emission of diesel engine.

• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.127-134
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• 1984

As a series of studies to clarify clonorchicidal substances in body surface mucus of some freshwater fishes, the substance in the epidermal mucus of Cyprinus carpio was isolated by silica gel column and thin layer chromatography and analysed for its chemical nature. Wormicidal trial was done in vitro, and the results obtained are summarized as follows: The mucus was extracted by ethyl ether and separated into 4 fractions by column chromatography using benzene as solvent. The second fraction with yellowish red colour among them showed the strongest clonorchicidal effect. The yellowish red fraction obtained by column chromatography was then fractionated into 6 spots by thin layer chromatography with petrol/ etherjchloroform (30/70, v/v), and the Rf. 0.714 spot among the 6 spots showed the strongest effect. The Rf. 0.714 spot was further fractionated into 6 spots by thin layer chromatography with benzene/acetone (90/10, vlv), and the Rf. 0.800 spot among the later 6 spots revealed the strongest effect. The Rf. 0.800 spot was chromatographed on column with benzene and 2 fractions were obtained. The second fraction of light brown colour represented the final purified fraction. By these Purification Procedures, clonorchicidal substance was Purified 15-fold with 0.035 yield from the mucus of C. carpio, and 10mg of the final fraction killed the cercaria in 26 min, the metacercaria in 115 min, and the adult in 443 min. Infra red and nuclear magnetic resonance spectrometric analysis of the purified substance revealed that the substance belongs to an ethyl ester of unsaturated fatty acid with 2 double bonds, 15 methylene groups and 1 methyl group.

• Journal of Pharmaceutical Investigation
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• v.39 no.1
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• pp.7-12
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• 2009

A novel polymeric tablet of Tinidazole was formulated to treat Helicobacter pylori and Giardia lambria more efficiently, It was possible to reduce hepatotoxicity by controlling the release of Tinidazole after peroral administration. A gastric retentive formulation made of naturally occurring carbohydrate polymers and containing Tinidazole was tested in vitro for swelling and dissolution characteristics. Tinidazole tablets containing various concentration of either PEO or HPMC were prepared by the wet granulation method. In vitro release of Tinidazole at pH 1.2 and pH 6.8 buffer solutions was observed at $37^{\circ}C$ by using a KP dissolution method and an UV (313 nm) spectrophotometer. Compared to a commercial Tinidazole tablet, in vitro release of Tinidazole at both pH 1.2 and pH 6.8 buffer solutions significantly decreased as the concentration of PEO or HPMC in the tablet increased up. And the gastric retentive formulation hydrated and swelled back to about 50% of its original size in 30 min. Thus, it was possible to control the release of Tinidazole by changing the content of PEO or HPMC in the tablet, thereby manipulating the release rate and the retention of Tinidazole.

• Macromolecular Research
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• v.13 no.2
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• pp.120-127
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• 2005

Conventional poly(methyl methacrylate) (PMMA) bone cement has been widely used as an useful biopolymeric material to fix bone using artificial prostheses. However, many patients had to be reoperated, due to the poor mechanical and thermal properties of conventional PMMA bone cement, which are derived from the presence of unreacted MMA liquid, the shrinkage and bubble formation that occur during the curing process of the bone cement, and the high curing temperature ($above 100^{\circ}C$) which has to be used. In the present study, a composite PMMA bone cement was prepared by impregnating conventional PMMA bone cement with ultra high molecular weight polyethylene (UHMWPE) powder, in order to improve its mechanical and thermal properties. The UHMWPE powder has poor adhesion with other biopolymeric materials due to the inertness of the powder surface. Therefore, the surface of the UHMWPE powder was modified with two kinds of silane coupling agent containing amino groups (3-amino propyltriethoxysilane ($TSL 8331^{R}$) and N-(2-aminoethyl)-3-(amino propyltrimethoxysilane) ($TSL 8340^{R}$)), in order to improve its bonding strength with the conventional PMMA bone cement. The tensile strengths of the composite PMMA bone cements containing $3 wt\%$ of the UHMWPE powder surface-modified with various ratios of $TSL 8331^{R}$ and $TSL 8340^{R}$ were similar or a little higher than that of the conventional PMMA bone cement. However, no significant difference in the tensile strengths between the conventional PMMA bone cement and the composite PMMA bone cements could be found. However, the curing temperatures of the composite PMMA bone cements were significantly decreased.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.395-401
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• 2014

In this work, the reaction characteristics for the non-catalytic esterification of palm fatty acid distillate were analyzed. The esterification reaction was assumed as the pseudo homogeneous $2^{nd}$ order reversible reaction and 'reaction effectiveness factor (${\eta}$)' was used to take accounts into evaporation and reaction of water and methanol, which take place simultaneously in the liquid phase. The nonlinear programming was used to derive appropriate kinetic parameters, the reaction rate constant and mass transfer coefficient, minimizing the error between experimental data and the numerical values. Based on these parameters, the apparent activation energy was calculated to be 43.98 kJ/mol.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.204-204
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• 1999

The plasma source ion implantation(PSII) technique which is a method using high negative voltage pulse in plasma system has the potential to change the surface properties of polymer. PSII technique increase the surface free energy by introducing polar functional groups on the surface so that it improves reactivity, hydrophilicity, adhension, biocompatability, etc. However, the mobility of polymer chains enables the modified surface layers to adapt their composition to interfacial force. This hydrophobic recovery interrupts the stability of modified surfaces to keep for the long time. In this study, poly(methyl methacrylate)(PMMA), poly(2-hydroxyethyl methacrylate)(PHEMA), and polu(2-hydroxypropyl methacylate)(PHPMA) for contact lens application, were modified to improve the wettability with PSII technique and were investigated the surface stabilities. Polymer film was prepared with solution casting(3 wt.% solution) and was annealed at 11$0^{\circ}C$ under vacuum oven to remove solvent completely and to eliminate physical ageing. The thickness of the film measured by scanning electron microscopy (SEM) and surface profilometer was about 10${\mu}{\textrm}{m}$. Polymers were treated with different kinds of gases, pulse frequency, pulse with, pulse voltage, and treatment time. Even though PMMA, PHEMA, and PHPMA have similar repeat unit structure, the optimal treatment conditions and the tendency to hydrophobic recovery were different. PHPMA, more hydrophilic polymer than PMMA and PHEMA showd better wettability and stability after mild treatment. Surface tensions were obtained by water and diiodomethane contact angle measurements to monitor the relation between hydrophobic recovery and polymer structure. Different ion species in plasma change the polar component and dispersion component of polymer surface. For better wettability surface, the increase of polar component was a dominant factor. We also characterized modified polymer surfaces using x-ray photoelectron spectroscopy(XPS), secondary ion mass spectrometry(SIMS), Fourier Transform infrared spectroscopy(FT-IR), and SEM.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.50-58
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• 1996

Interspecific hybrids between Aspergillus oryzae var oryzae and A. nidulans 514 were obtained by nuclear transfer technique. Several autotrophic mutants isolated from conidiospores of the two strains were mutagenized with ultraviolet and N-methyl-N-nitrosoguanidine. Optimal conditions for formation of intergeneric hybrids were investigated. Frequencies of hybrid formation by nuclear transfer were $3{\times}10^{-5}{\sim}1{\times}10^{-5}$. From observation of genetic stability, conidial size, DNA content, and nuclear stain, it was suggested that their karyptypes are aneuploid. The hybrids showed 1.1~1.4 fold higher xylanase activities than parental strains did. The xylanase of Aspergiilus sp. TAVD514-3 was purified and some of it's enzymatc characteristics were investigated. The enzyme was purified about 85 fold with an overall yield of 17% from the culture medium by ammonium sulfate fractionation, Sephadex G-75 gel permeation chromatography, and CM-sephadex A-50 ion exchange chromatography. The purified enzyme functions optimally at pH 9.0 and 80$^{\circ}C$. The enzymatic activity was increased by the presence of $Mg^{2+}$ and $Mn^2$ ions.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.217-222
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• 1983

By the treatment of Gibberella fujkuroi I-892 with mutagen such as UV light and N-methyl-N'-nitro-N-nitrosoguanidine, a mutant G. fujkuroi G-471 was selected as the highest producer of gibberellic acid among 800 mutant strains. It showed 30% increase of production yield compared with that of the parent strain. At optimum medium composition (saccharose 1.0%, ammonium tartarate 50mM, malt extract 1.0% KH$_2$PO$_4$ 0.5%, MgSO$_4$0.5%, FeSO$_4$0.0002%, trace element sol.0.002% (v/v), the yield of submerged culture increased by 30% after 7 days culture at 24$^{\circ}C$ (253mg/$\ell$). In submerged culture, the initial pH showed much effects on the increase of gibberellic acid production. The highest yield of the production was attained with pH adjustment to 4.0 at the initial stage of fermention.

• Korean Journal of Pharmacognosy
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• v.49 no.1
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• pp.15-22
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• 2018

The aim of this study was to develop a UPLC method for simultaneous analysis of 8 phenolic compounds including gallic aicd (1), protocatechuic acid (2), methyl gallate (3), ellagic acid (4), kaempferol-3-arabinofranosyl-7-rhamnoside (5), kaempferitrin (6), afzelin (7) and kaempferol-7-rhamnoside (8) isolated from Geranium thunbergii which has been traditionally used as anti-diarrheal agent. The UPLC method was optimized and validated using Halo C18 column ($4.6{\times}100mm$, $2.7{\mu}m$) consisting of MeOH and 0.1% formic acid at 260 nm in 25 minutes. In quantitative analysis of 8 compounds in MeOH extract of G. thunbergii, contents of 4-6 were 12.39, 20.52 and 21.45 mg/g, respectively. These compounds were measured as major phenolic compounds in G. thunbergii and can be useful as marker compounds for its quality control. These results suggest that the UPLC method can be contributed as basic data for quality evaluation of herbal preparations.