• 농약과학회지
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• 제2권1호
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• pp.18-23
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• 1998

유기합성을 통한 천연물기원 신농약 선도물질을 얻기 위해 피마자잎으로부터 동정된 활성물질 ricinine의 합성방법을 설정한 후 살충활성을 조사하였다. Ricinine은 4단계과정의 cyanoacetic acid 중합반응과 malono nitrile의 단순고리화 반응 2가지 방법으로 합성하였으며 합성 수율은 중합반응보다 단순고리화 반응에서 높은 수율을 나타냈다. 합성된 ricinine및 중간생성물의 살충활성 조사결과 1,000 ${\mu}g/ml$ 농도수준에서 ricinine은 벼멸구와 콩바구미에 대해 각각 80%, 75%의 살충력을 나타냈다. 점박이응애의 경우 분자구조내에 chloride 기가 존재하는 chloronorricinine과 chlororicinic acid가 500 ${\mu}g/ml$ 수준에서 60%의 살충효과를 보여주었으며, 10 ${\mu}g/ml$ 수준에서 빨간집모기 유충에 대한 활성은 chlororicinine이 44%의 살충력을 나타냈다.

• 약학회지
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• 제42권2호
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• pp.159-164
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• 1998

The secondary hydroxy group at side chain of shikonin structure was selectively acylated with various haloacetic acids in presence of dicyclohexylcarbodiimide and 4-dimethylamin opyridine to produce haloacetylshikonin derivatives. The cytotoxicity of monohaloacetylshikonin derivatives against L1210 cells increased in the following order; monochloroacetylshikonin ($ED_{50}$, 0.142${\mu}$g/ml) > monobromoacetylshikonin ($ED_{50}$. 0.158${\mu}$g/ml) > monoiodoacetylshikonin ($ED_{50}$, 0.173${\mu}$g/ml). Introduction of larger halogen atoms decreased the cytotoxic activity, presumably due to steric hinderance. The cytotoxicity of chloroacetylshikonin derivatives was dependent on the number of chlorine atom, thus increasing in the following order; trichloroacetylshikonin (0.032${\mu}$g/ml) > dichloroacetylshikonin (0.059${\mu}$g/ml) > monochloroacetylshikonin ($ED_{50}$, 0.142${\mu}$g/ml). Thus, the electron withdrawing effect seems to be important for the cytotoxicity of chloroacetylshikonin derivatives. Consistent with the above, dichloroacetylshikonin (T/C. 182%) and trifluoroacetylshikonin (195%) showed higher T/C values than monochloroacetyl-(T/C, 122%), monobromoacetyl-(T/C, 154%) and monoiodoacetylshikonin (T/C, 117%) derivatives. Haloacetylshikonin derivatives showing lower cytoxic activities against L1210 cells exhibited lower T/C values. It seems that there is a relationship between the cytoxicity of haloacetylshikonin and their antitumor activity.

• Journal of Acupuncture Research
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• 제36권1호
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• pp.33-37
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• 2019

Background: This study was designed to investigate the potential effects of Galgeungyulpitang for whitening and elasticity treatment by examining its effect on melanoma cells. Methods: The effects of Galgeungyulpitang on B16/F10 melanoma cell viability, production of melanin, tyrosinase and elastase, were investigated. Cell viability was measured by colorimetric assay that assesses cell metabolic activity (MTT assay). Melanin was measured by Hosei's method, tyrosinase was measured by Yogi's method and elastase was measured by James's method. Results: At concentrations higher than $500{\mu}g/mL$ Galgeungyulpitang, cell viability was significantly reduced ($p{\leq}0.05$). At concentrations of $500{\mu}g/mL$ and lower, morphological changes were not observed. The rate of melanin synthesis was significantly reduced to $73.49%{\pm}2.92%$ at a concentration of $500{\mu}g/mL$ Galgeungyulpitang compared with untreated cells (p < 0.05). Extracellular tyrosinase production was not significantly decreased in vitro, however, intracellular tyrosinase production was significantly reduced to $76.06%{\pm}2.17%$ when treated with Galgeungyulpitang at a concentration of $500{\mu}g/mL$ compared with the control (p < 0.05). Elastase Type 1 production was significantly reduced to $74.98%{\pm}3.24%$ and $69.62%{\pm}4.66%$ at concentrations of 250 and $500{\mu}g/mL$ Galgeungyulpitang, respectively (p < 0.05). Elastase Type 4 production was significantly reduced to $72.77%{\pm}3.52%$ at concentrations of 250 and $500{\mu}g/mL$ (p < 0.05). Conclusion: The results in this study showed that Galgeungyulpitang may inhibit melanin and tyrosinase synthesis, and inhibit elastase production, suggesting that Galgeungyulpitang may be potentially beneficial for skin whitening and loss of skin elasticity treatments.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.501-508
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• 2000

It is demanded to find the dynamic model of a real structure to design a controller. However, as the structure has inherently infinite number of degree-of-freedom, it is impossible to obtain an exact dynamic model of the structure. Instead a reduction model with finite degree-of-freedom is used for the design of a controller. So there exists uncertainty between a real model and a reduction model which causes poor performance of control. All these uncertainties can degrade the control performance and even cause the control instability. Thus, robust control strategy considering the above uncertainties can be an alternative one to guarantee the performance and stability of the control. This study deals with the experimental verification of robust controller design for the active mass driver. $\mu$-synthesis technique is employed as a robust control strategy. Some weights are chosen based on the difference between the initial plant with which the controller is designed and the perturbed plant to be controlled having the actuator uncertainty. The robustness of $\mu$-synthesis technique is compared with the result of LQG strategy, which does not consider the uncertainty.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2574-2580
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• 2012

The discovery that threosyl phosphonate nucleoside (PMDTA, $EC_{50}=2.53{\mu}M$) is a potent anti-HIV agent has led to the synthesis and biological evaluation of 5'-deoxy versions of threosyl phosphonate nucleosides. In the present study, (E)-3'-phosphonoalkenyl and 3'-phosphonoalkyl nucleoside analogues 13, 16, 20 and 23 were synthesized from acetol and tested for anti-HIV activity and cytotoxicity. The adenine analogue 16 was found to exhibit moderate in vitro anti-HIV-1 activity ($EC_{50}=22.2{\mu}M$).

• BMB Reports
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• 제30권3호
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• pp.211-215
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• 1997

A photoactive analog of ATP, 3'(2')-O-(p-azidobenzoyl)-adenosine 5-triphosphate (AB-ATP) was synthesized by chemically coupling N-hydroxysuccinimidyl-4-azidobenzoate (NHS-AB) and ATP. The utility of AB-ATP as an effective active-site-directed photoprobe was demonstrated using catalytic subunit of protein kinase A as a model enzyme. Photoincorporation of AB-ATP was saturated with apparent dissociation constant of $30{\mu}m$ and protected completely by $100{\mu}m$ of ATP. When the enzyme was covalently modified by photolysis in the presence of saturating amounts of photoprobe, about 60% inhibition of enzyme activity was observed. These results demonstrate that AB-ATP has potential application as a probe to characterize ATP-binding proteins including protein kinases.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1146-1152
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• 2011

The discovery of 2'-spirocyclopropyl-ribocytidine (J. Med. Chem. 2010, 53, 8150-8160) as a potent inhibitor of RNA synthesis by NS5B ($IC_{50}=7.3{\mu}M$), the RNA polymerase encoded by hepatitis C Virus (HCV), has led to the synthesis and biological evaluation of several carbocyclic versions of 2'-spiropropyl-nucleosides. The cyclopentenol intermediate 7 was successfully constructed via ring-closing metathesis (RCM) from divinyl 6. Spirocyclopropanation of enone 8 was effected by using (2-chloroethyl)-dimethylsulfonium iodide and potassium tert-butoxide to form the desired intermediate 9. The synthesized nucleoside analogues 21-24 were assayed for their ability to inhibit HCV RNA replication in a subgenomic replicon Huh7 cell line. Among them, the cytosine nucleoside analogue 22 exhibited significant anti-HCV activity ($EC_{50}= 8.2{\mu}M$).

• Applied Biological Chemistry
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• 제35권6호
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• pp.470-474
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• 1992

해양환형동물 thelepus setosus로부터 분리된 thelepin ${\underline{2}}$의 항균활성에 착안하여 새로운 항균성 선도구조를 찾아내고자, B 환구조를 coumaran형에서 chroman-4-one형으로 전환하고 생물활성을 조사하였다. Thelepin의 spirobenzopyranone 유도체를 산화적분자내에 환반응을 이용하여 합성하였으며 진균 2종과 박테리아 2종을 대상으로 paper disc법으로 생물활성을 조사한 결과 gram-positive 박테리아인 Bacillus subtilis에 대하여 $5\;{\mu}g/disc$ 수준에서 억제 활성을 보였다.

• The Korean Journal of Ceramics
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• 제1권3호
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• pp.147-151
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• 1995

Porous composite of $Al_2O_3$ and AIN based mullite and SiC can be prepared by alumium reaction synthesis and atmosphere controllied sintering in order to improve the durability of a gas filter body. The porous $Al_2O_3$-AIN-mullite, which has a strength of 168 kg/$\textrm{cm}^2$ and porosity of 51.59%, could be obtained by stmospheric firing at $1600^{\circ}C$ and the porous $Al_2O_3$-AIN-SiC with a porosity of 33% and strength of 977 kg/$\textrm{cm}^2$, could also be prepared. The average pore size has been changed from 0.2$\mu\textrm{m}$ in a reduction atmosphere and to 2$\mu\textrm{m}$ in an air atmosphere, respectively.

• 한국입자에어로졸학회지
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• 제5권3호
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• pp.111-122
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• 2009

This paper reviews about synthesis of nanoparticles by spark discharge and applications. A method of catalytic activation with Pd and Pt aerosol nanoparticles produced by spark discharge was introduced. After annealing, the catalytically activated substrate placed into a solution for electroless silver deposition. The silver was then formed only on the activated regions of the substrate. Silver line patterns having a width of $18{\mu}m$ and a height of $1{\mu}m$ were created with the ability to be effectively reproduced. Antimicrobial nanoparticles such as silver were used for removal of bioaerosols. Silver nanoparticles deposited air filters such as ACF filters were evaluated by antimicrobial test.