• Tribology and Lubricants
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• v.32 no.5
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• pp.141-146
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• 2016

The diketopyrrolopyrrole (DPP) pigment is a bicyclic 8-π-electron system containing two lactam units. Typical DPP derivative pigments have melting points of over 350°C and very low solubility in most solvents, and show absorption in the visible region with a molar extinction coefficient of 33,000 dm²mol⁻¹ and strong photoluminescence with maxima in the range 500–600 nm. X-ray structure analyses of DPP show that the whole molecule is almost in one plane. The phenyl rings are twisted out of the heterocyclic plane and the intermolecular hydrogen bonding between neighboring lactam NH and carbonyl units influences the structure of the DPP pigment in the solid state. In this study, mono-N-alkylation and mono-N-arylation were undertaken for Pigment Red 264 or Pigment Orange 73 with alkyl halide and aryl halide, respectively, in the presence of sodium tert-butoxide as a base catalyst to improve the solubility of DPP pigments and their application as CO₂ indicators. The synthetic yield was in the range 11–88%. The indicator dyes are highly soluble in organic solvents and shows pH-dependent absorption (λ_max 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission (λ_max 524 and 605 nm for the protonated and deprotonated forms, respectively) spectra. The mono-N-alkylated and mono-N-arylated DPP pigment was identified by ¹H-NMR (¹H-Nuclear Magnetic Resonance Spectrometer), FT-IR (Fourier Transform Infrared Spectroscopy), and MS (Mass Spectrometry). According to the results of color and hue properties obtained by a color matching analyzer, the synthesized DPP pigment material can be used as a CO₂ indicator.

• Molecular & Cellular Toxicology
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• v.2 no.3
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• pp.151-158
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• 2006

Khal was a synthetic congener of halocidin, a heterodimeric peptide consisting of 19 and 15 amino acid residues detected in Halocynthia aurantium. This compound was considered a candidate for the development of a novel peptide antibiotic. The genotoxicity of Khal was subjected to high throughput toxicity screening (HTTS) because they revealed strong antibacterial effects. Mouse lymphoma thymidine kinase ($tk^{+/-}$) gene assay (MOLY), single cell gel electrophoresis (Comet) assay and chromosomal aberration assay in mammalian cells and Ames reverse mutation assay in bacterial system were used as simplified, inexpensive, short-term in vitro screening tests in our laboratory. These compounds are not mutagenic in S. typhimurium TA98 and TA100 strains both in the presence and absence of metabolic activation. Before performing the comet assay, $IC_{20}$ of Khal was determined the concentration of $25.51\;{\mu}/mL\;and\;21.99\;{\mu}g/mL$ with and without S-9, respectively. In the comet assay, Khal was not induced DNA damage in mouse lymphoma cell line. Also, the mutation frequencies in the Khal-treated cultures were similar to the vehicle controls. It is suggests that Khal is non-mutagenic in MOLY assay. And no clastogenicity was observed in Khal-treated Chinese hamster lung cells. The results of this battery of assays indicate that Khal has no genotoxic potential in bacterial or mammalian cell systems. Therefore, we suggest that Khal, as the optimal candidates with both no genotoxic potential and antibacterial effects must be chosen.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.185-196
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• 1992

To assess its suitability as a prodrug of 5-fluorouracil (5-FU), 1-glycyloxymethyl-5-FU HCl (GFU), a 5-fluorouracil derivative having a glycyloxymethyl group at the N-l position was synthetized. Its physicochemical properties and hydrolysis kinetics, in aqueous solution of pH $1{\sim}10$ and in the presence of human plasma or rat liver homogenate were studied. Its acute toxicity and antitumor activity against sarcoma 180 were also examined, GFU showed higher lipid/water partition coefficient than 5-FU. The calculated $pK_{\alpha}$ values of 5-FU and GFU were 8.02 and 7,20, respectively. The decomposition rates of GFU in aqueous solution showed a pH-dependence over the pH range used, which could be ascribed to solvent catalysed hydrolysis reaction at pH lower than 4,16 and to specific hydroxide ion hydrolysis reaction at pH higher than 4,16, The half-life of GFU was 6,9 min in 80% human plasma solution and less than 3 min in rat liver homogenate at $37^{\circ}C$, The $LD_{50}$ value of 5-FU was 240 mg/kg while that of GFU was 440.6 mg/kg (226 mg as 5-FU). Both of 5FU and GFU showed a strong antitumor activity, Therapeutic ratios of 5-FU and GFU were 3.07 and 3.55, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.2
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• pp.139-148
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• 2012

The MLS(Moving Least Squares) Difference Method is a numerical scheme that combines the MLS method of Meshfree method and Taylor expansion involving not numerical quadrature or mesh structure but only nodes. This paper presents an dynamic algorithm of MLS difference method for solving transient solid mechanics problems. The developed algorithm performs time integration by using Newmark method and directly discretizes strong forms. It is very convenient to increase the order of Taylor polynomial because derivative approximations are obtained by the Taylor series expanded by MLS method without real differentiation. The accuracy and efficiency of the dynamic algorithm are verified through numerical experiments. Numerical results converge very well to the closed-form solutions and show less oscillation and periodic error than FEM(Finite Element Method).

• Journal of the Korean Chemical Society
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• v.22 no.4
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• pp.239-244
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• 1978

Spectroscopic studies of trans-1,2-bispyrazylethylene (BPE), one of the stilbene analogues, were carried out. In normal UV spectra, a distinct $n{\rightarrow}{\pi}^*$ absorption band is missing because of a strong, nearly isoenergetic ${\pi}{\rightarrow}{\pi}^*$ absorption band. The second derivative and low temperature $(77^{\circ}K)$ UV absorption spectra were taken and $n{\rightarrow}{\pi}^*$ absorption band was identified by these methods. The transition energies of ${\pi}{\rightarrow}{\pi}^*$ transitions were calculated by Pariser-Parr-Pople (PPP)-SCF-CI MO method. The calculated values showed good agreement with the observed spectral data. Luminescence studies were also carried out at low temperature. From the fluorescence spectra, fluorescence polarization studies, and PPP-SCF-CI MO calculation, the fluorescent state was determined to be a singlet $({\pi},\;{\pi}^*)$ state. This conclusion is in good agreement with the results obtained from alkaline salt effects on the fluorescence of this compound.

• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.239-244
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• 2009

In order to alleviate the cyto-toxicity and improve the poor water solubility of 7-hydroxy-3-methoxycadalene, it was substituted with glucose, a strong hydrophilic and non cyto-toxiccompound, in the C-7 position. The yield of final product was ca. 55.4%. The $IC_{50}$ values of 7-O-${\beta}$-D-glucopyranosyl-3-methoxycadalene against normal lung cell (WI-38 cell line) and human lung cancer cell (A-549 cell line), which is a parameter for determination of cell viability, were measured to $298.2{\mu}m$ and $88.6{\mu}m$, respectively. This result indicates that the pharmaceutical efficiency of the cadalene-glucose derivative targeted to lung cancer cell could be improved more than three times compared to the non derivatized cadalene. In addition, glycosylation of 7-hydroxy-3-methoxycadalene turned its hydrophobic property to more soluble in water.

• BMB Reports
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• v.51 no.4
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• pp.188-193
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• 2018

Caffeoylserotonin (CaS), one derivative of serotonin (5-HT), is a secondary metabolite produced in pepper fruits with strong antioxidant activities. In this study, we investigated the effect of CaS on proliferation and migration of human keratinocyte HaCaT cells compared to that of 5-HT. CaS enhanced keratinocyte proliferation even under serum deficient condition. This effect of CaS was mediated by serotonin 2B receptor (5-HT2BR) related to the cell proliferation effect of 5-HT. We also confirmed that both CaS and 5-HT induced G1 progression via 5-HT2BR/ERK pathway in HaCaT cells. However, Akt pathway was additionally involved in upregulated expression levels of cyclin D1 and cyclin E induced by CaS by activating 5-HT2BR. Moreover, CaS and 5-HT induced cell migration in HaCaT cells via 5-HT2BR. However, 5-HT regulated cell migration only through ERK/AP-1/MMP9 pathway while additional Akt/NF-${\kappa}B$/MMP9 pathway was involved in the cell migration effect of CaS. These results suggest that CaS can enhance keratinocyte proliferation and migration. It might have potential as a reagent beneficial for wound closing and cell regeneration.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.39-48
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• 2013

This paper develops a 2-D moving least squares(MLS) difference method for Stefan problem by extending the 1-D version of the conventional method. Unlike to 1-D interfacial modeling, the complex topology change in 2-D domain due to arbitrarily moving boundary is successfully modelled. The MLS derivative approximation that drives the kinetics of moving boundary is derived while the strong merit of MLS Difference Method that utilizes only nodal computation is effectively conserved. The governing equations are differentiated by an implicit scheme for achieving numerical stability and the moving boundary is updated by an explicit scheme for maximizing numerical efficiency. Numerical experiments prove that the MLS Difference Method shows very good accuracy and efficiency in solving complex 2-D Stefan problems.

• Journal of Korean Medicine for Obesity Research
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• v.20 no.1
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• pp.1-9
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• 2020

Objectives: Artemisinin and its derivatives extracted from Artemisia annua, a Chinese herbal medicine, have variable biological effects due to structural differences. Up to date, the anti-obesity effect of dihydroartemisinin (DHA), a derivative of artemisinin, is unknown. The purpose of this study was to investigate the anti-adipogenic and lipolytic effects of DHA on 3T3-L1 preadipocytes. Methods: Oil Red O staining and AdipoRed assay were used to measure lipid accumulation and triglyceride (TG) content in 3T3-L1 cells, respectively. Cell count analysis was used to determine the cytotoxicity of 3T3-L1 cells. Western blot and real-time reverse transcription polymerase chain reaction analyses were used to analyze the expression of protein and mRNA in 3T3-L1 cells, respectively. Results: DHA at 5 μM markedly inhibited lipid accumulation and reduced TG content in differentiating 3T3-L1 cells with no cytotoxicity. Furthermore, DHA at 5 μM inhibited the expression of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), and perilipin A as well as the phosphorylation of signal transducer and activator of transcription-3 (STAT-3) in differentiating 3T3-L1 cells. Moreover, while DHA at 5 μM had no effect on the mRNA expression of adiponectin, it strongly suppressed that of leptin in differentiating 3T3-L1 cells. However, DHA at 5 μM had no lipolytic effect on differentiated 3T3-L1 cells, as assessed by no enhancement of glycerol release. Conclusions: These results demonstrate that DHA at 5 μM has a strong anti-adipogenic effect on differentiating 3T3-L1 cells through the reduced expression and phosphorylation of C/EBP-α, PPAR-γ, FAS, perilipin A, and STAT-3.

• YAKHAK HOEJI
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• v.45 no.5
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• pp.468-475
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• 2001

Fenofibrate is a fibric acid derivative that is a strong reducer of triglyceride. Micronozed formulation of fenofibrate has improved bioavailability compared to non-micrornized formulation. This study performed a retrospective comparison of micrornized and non-micrornized fenofibrate (28 in micronized and 51 in non-micronized group) by comparing the means of changes in total triglyceride, total cholesterol, HDL-cholesterol and TC/HDL ratio in type 2 diabetics with dyslipidemia The result skewed that after 12 weeks of treatment both drugs produced a significant reduction in total triglyceride levels (62% with micronized, 37% with non-micronized). The mean decrease observed for total triglyceride levels were significantly lower for micronized fenofibrate (p<0.001). Both drugs showed a significant reduction for total cholesterol levels (-22% with micronized, -14% with non-micronized fenofibrate). The mean decrease observed for total cholesterol was not significantly different between the two drugs (p>0.05). HDL-cholesterol levels increased by 24% and 15%) with micronized and non-micronized, respectively and the differences from the baseline were statistically significant for both drugs (p<0.05). The mean change of HDL-cholesterol was not significantly different between the two drugs. There was a statistically significant reduction in TC/HBL-cholesterol ratio from baseline for both drugs (7.1 to 4.8 with micronized and 5.1 to 4.5 with non-micronized), and the reduction of TC/HDL-cholesterol ratio tended to be significantly greater with micronized fenofibrate (p<0.05). This study shows that short-term treatment with micronized fenofibrate is more effective than non-micronized fenosbrate in type 2 diabetes patients with dyslipidemia.