• 농약과학회지
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• 제2권1호
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• pp.24-31
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• 1998

천연물기원 신농약 개발을 위해 유용 식물자원 탐색 및 활성물질의 분리, 동정 결과 벼멸구 살충활성이 높고 분자구조상 유기합성이 용이한 것으로 판단되는 피마자잎중 활성물질 ricinine의 유도체 합성을 통해 고활성 화합물을 얻고자 하였다. 합성된 ricinine을 선도물질로 하여 활성을 증진하고자 분자구조 유사화합물을 비롯한 카바메이트계, 유기인계 화합물 12종을 합성하였다. 카바메이트계 유도체 합성시 전구물질의 pyridine 구조중 carbo기가 있는 chlororicinic acid, ricinic acid는 공명구조가 파괴되어 methyl isocyanate와 반응이 이루어지지 않았다. 유기인계 유도체의 경우 P에 O와 S가 결합된 oxon과 thiono형의 유도체를 합성한 결과 합성수율은 oxon형이 65% 이상인 반면에 thiono형은 20% 미만으로서 낮은 수율을 보였다. 합성 유도체의 생리활성 평가에 있어 유기인계 유도체는 oxon형보다 thiono형 화합물이 높은 살충효과를 나타냈다. Thiono형 유도체는 500 ${\mu}g/ml$ 수준에서 벼멸구에 대한 살충력이 모두 100%이었으며 점박이응애의 경우 특이적으로 thiono형 유도체중 alkyl기의 부분이 methyl인 경우 높은 활성을 나타냈다. Oxon형 유도체, 분자구조 유사화합물과 카바메이트계 유도체의 경우에는 살충력이 나타나지 않았다. 살균 활성은 pyridine ring의 2번 위치에 $NH_{2}$기가 있는 유도체의 경우 200 ${\mu}g/ml$ 수준의 실내검정에서 10종 병원균에 대해 $85{\sim}100%$의 생장저지효과를 보여주었으며, 온실검정에서도 250 ${\mu}g/ml$ 수준에서 벼도열병과 보리흰가루병에 대해 각각 92%, 86%의 방제효과를 나타냈다.

• 한국항공우주학회지
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• 제43권3호
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• pp.232-242
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• 2015

기동 성능과 스텔스 성능을 극대화시키기 위해 무미익 람다(lambda) 형상의 무인전투기에 대한 연구개발이 각 국에서 활발히 진행되고 있다. 이러한 형상의 비행체는 불안정한 동적 비행특성을 가질 가능성이 높으며, 이를 비행제어 시스템으로 제어하기 위해서는 보다 정확한 동안정 미계수 예측이 필수적이다. 본 연구에서는 풍동기법의 단점을 보완하고 순수 공기역학적 동안정 미계수를 예측하기 위해 전산유체역학의 Dynamic Mesh 기법을 적용하여 강제진동법을 모사하였고, 해석결과를 기존에 확보한 시험결과와 비교하여 검증하였다. 해석결과는 종축 동안정 미계수에 국한하였으며, 무미익 람다 형상의 기준 받음 각, 진동주파수, 진동폭 등의 변화에 따른 동안정 미계수 변화 경향성을 파악하였다. 전산해석 결과는 풍동시험 데이터와 유사한 경향성을 보였으며, 제시된 연구기법을 통해 항공기 동안정 미계수를 효율적으로 구할 수 있음을 확인하였다.

• Biomolecules & Therapeutics
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• 제12권4호
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• pp.250-256
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• 2004

Cordyceps possesses numerous health-promoting ingredients including hypoglycemic agents. The mechanism for the reduction of circulatory sugar content, however, is still not fully understand. In this study, 4-beta acetoxyscirpendiol (ASD) was purified from the methanolic extracts from fruiting bodies of Paecilomyces tenuipes. Na+/Glucose transporter-1 (SGLT-1) was expressed in the Xenopus oocytes. The effect of ASD on the oocyte expressed SGLT-1 was analyzed utilizing the voltage clamp and 2-deoxy-D-glucose (2-DOG) uptake studies. ASD was shown to significantly inhibit SGLT-1 activity compared to the non-treated control in a dose- dependent manner. In the presense of its two derivatives (diacetoxyscirpenol or 15-acetoxyscirpendiol), SGLT-1 activity was greatly inhibited similarly as ASD. Between ASD derivatives, 15-acetoxyscirepenol showed inhibition equivalent to that of ASD while diacetoxyscirpenol did less degree of inhibition. Insummary , these results strongly indicate that ASD in P. tenuipes may serve as a functional substance in lowering blood sugar in the circulatory system. ASD and its derivatives can be utilized as inhibitors of SGLT-1.

• BMB Reports
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• 제38권2호
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• pp.211-217
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• 2005

Cordyceps, an entomopathogenic fungus, contains many health-promoting ingredients. Recent reports indicate that the consumption of cordyceps helps reduce blood-sugar content in diabetics. However, the mechanism underlying this reduction in circulatory sugar content is not fully understood. Methanolic extracts were prepared from the fruiting bodies of Paecilomyces tenuipes, and 4-beta acetoxyscirpendiol (4-ASD) was eventually isolated and purified. $Na^+$/Glucose transporter-1 (SGLT-1) was expressed in Xenopus oocytes, and the effect of 4-ASD on SGLT-1 was analyzed utilizing a voltage clamp and by performing 2-deoxy-D-glucose (2-DOG) uptake studies. 4-ASD was shown to significantly inhibit SGLT-1 activity compared to the non-treated control in a dose-dependent manner. In the presence of the derivatives of 4-ASD (diacetoxyscirpenol or 15-acetoxyscirpendiol), SGLT-1 activity was greatly inhibited in an 4-ASD-like manner. Of these derivatives, 15-acetoxyscirepenol inhibited SGLT-1 as well as 4-ASD, whereas diacetoxyscirpenol was slightly less effective. Taken together, these results strongly indicate that 4-ASD in P. tenuipes may lower blood sugar levels in the circulatory system. We conclude that 4-ASD and its derivatives are effective SGLT-1 inhibitors.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.882-885
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• 2004

Organic molecules have many properties that make them attractive for electronic applications. We have been examining the progress of memory cell by using molecular-scale switch to give an example of the application using both nanoscale components and Si-technology. In this study, molecular electronic devices were fabricated with amion style derivatives as redox-active component to compare to the devices using Zn-Porphyrin derivatives. This molecule is amphiphilic to allow monolayer formation by the Langmuir-Blodgett (LB) method, and then this LB monolayer is inserted between two metal electrodes. According to current-voltage (I-V) characteristics, it was found that the devices show remarkable hysteresis behavior and can be used as memory devices at ambient conditions, when aluminum oxide layer was existed on bottom electrode. Diode-like characteristics were measured only, when Pt layer was existed as bottom electrode. It was also found that this metal layer interacts with the organic molecules and acts as a protecting layer, when thin Ti layer was inserted between the organic molecular layer and the top Al electrode. These electrical properties of the devices may be applicable to active components for the memory and/or logic gates in the future.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.299-306
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• 2006

Using a level set method and topological derivatives, a topological shape optimization method that is independent of an initial design is developed for linearly elastic structures. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. The 'Hamilton-Jacobi (H-J)' equation and computationally robust numerical technique of 'up-wind scheme' lead the initial implicit boundary to an optimal one according to the normal velocity field while minimizing the objective function of compliance and satisfying the constraint of allowable volume. Based on the asymptotic regularization concept, the topological derivative is considered as the limit of shape derivative as the radius of hole approaches to zero. The required velocity field to update the H -J equation is determined from the descent direction of Lagrangian derived from optimality conditions. It turns out that the initial holes is not required to get the optimal result since the developed method can create holes whenever and wherever necessary using indicators obtained from the topological derivatives. It is demonstrated that the proper choice of control parameters for nucleation is crucial for efficient optimization process.

• Archives of Pharmacal Research
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• 제23권2호
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• pp.128-138
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• 2000

In continuation of the previous work (Fathalla, 1992) on the synthesis of some heterocycles containing uracil moiety, we report herein the incorporation of uracil moiety into cyan-opyridine thione, thiosemecarbazone, semicarbazone, cyanopyridine, ami nocyano pyridine, isoxazoline, pyrazoline, pyrimidine, triazolo pyrimidine, pyran, selena and thiazole derivatives which might modify their biological activities. The biological studies revealed that the chemical compound III f showed high molluscicdal activity than other compounds. The profile of the nucleoprotein extracted from chemically (compound IIIc, e, f and g) treated or UV-irradiated B.alexandrina snails did not show appreciable differences when compared to non-treated (native) snails by using SDS-PAGE, where no obvious qualitative or quantitative differences were observed. Immunization of experimental animals with the nucleoprotein extracted from native, chemically (compound III f ＆ g) treated or physically treated B.alexandrina snails induced significant protection against challenge with normal S.mansoni cercariae, as compared to the non-immunized challenged control. As well as , a decrease in the number of granuloma formation and the size range of granuloma was also observed in immunized animals. It is concluded that, compounds III f and g have a potent molluscicidal activity. They also induced chemical modification comparable to that induced by physical treatment in the snail's nucleoprotein, which could possibly be used in immunization against S. mansoni infection.

• 통합자연과학논문집
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• 제7권4호
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• pp.253-259
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• 2014

Protein kinase C theta (PKC-${\theta}$) is a serine/threonine specific protein kinase. It is largely expressed in the T-cells and CD28 signaling. PKC-${\theta}$ phosphorylates diverse proteins that are involved in the various cellular signaling pathways. Activated PKC-${\theta}$ in turn activates other transcription factors that control the proliferation and differentiation of T- cells. PKC-${\theta}$ is considered to be an interesting therapeutic target due to its crucial role in the proliferation, differentiation and survival of T-cells. In the present study, we have performed ligand-based CoMFA study on a series of pyridylpyrazolopyridine derivatives as PKC-${\theta}$ inhibitors. An acceptable CoMFA model ($q^2$=0.544; ONC=4; $r^2$=0.876) was developed and validated by Bootsrapping and progressive sampling. The CoMFA contour map suggested the regions to increase the activity. Bulky substitutions in R2 position of the piperizine ring could increase the activity. Similarly positive, small substitution in the R1 position of the Pyridine ring could considerably increase the activity. Our work could assist in designing more potent PKC-${\theta}$ inhibitors of pyridylpyrazolopyridine derivatives.

• 대한약침학회지
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• 제24권1호
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• pp.32-40
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• 2021

Objectives: Pathogenic microbes are causal agents for various types of severe and even lethal infectious diseases. Despite of development in medication, bacterial and fungal infections still persist to be a vital problem in health care. Bacteria and several fungal species have shown resistance to antibiotics used in treatment to current medications. Therefore, it is a considerable field of interest in the design and development of novel compounds with antimicrobial activity. Methods: The compounds bearing a heterocyclic ring play an imperative role among other organic compounds with pharmacological activity used as drugs in human for control and cure of various infections. Thiadiazoles containing nitrogen-sulfur atom as part of their cyclic structure which shown wide-ranging application as structural units of biologically active molecules and are very useful intermediates in Medicinal Chemistry. Results: The effectiveness of the thiadiazole nucleus was established by the drugs currently used for the treatment of various infections. 1,3,4-Thiadiazoles and some of their derivatives are widely studied because of their broad spectrum of pharmacological activities. Conclusion: In the present work, a series of 1,3,4-Thiadiazole derivatives were synthesized by cyclization of a group of various benzaldehyde with thiosemicarbazide in the presence of various reagent like FeCl3, HCHO by losing a molecule of water. These derivatives were found to possess prominent antimicrobial activity.

• 한국응용곤충학회지
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• 제50권2호
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• pp.107-113
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• 2011

벤질리덴아세톤은 곤충병원세균인 Xenorhabdus nematophila의 배양액에서 유래된 물질이다. 벤질리덴아세톤은 아이코사노이드 생합성을 억제하여 곤충의 면역을 저하시키는 것으로 알려져 있으며, 이 물질을 미생물농약에 첨가하면 병원성의 제고 효과를 기대할 수 있다. 본 연구는 벤질리덴아세톤의 면역억제 능력을 제고시킬 목적으로 이 물질의 소수성을 낮추는 유도체를 화학 합성하였다. 수산기를 첨가한 두 가지 벤질리덴아세톤 유도체와 설탕이 부착된 벤질리덴아세톤 유도체가 각각 합성되었다. 이 유도체들은 모두 배추좀나방(Plutella xylostella)의 phospholipase $A_2$ ($PLA_2$)와 phenoloxidase (PO) 활성을 모두 억제하였으며, 이 가운데 벤질리덴아세톤이 가장 억제력이 높았다. 이러한 벤질리덴아세톤 유도체들을 각각 Bacillus thuringiensis (Bt) 생물농약과 혼합하면 미생물의 병원성을 증가시켰다. 벤질리덴아세톤은 또한 네 가지 식물병원성 진균의 성장을 억제시켰다. 그러나 이 물질의 유도체들(특히 설탕 중합체)의 병원균 성장 억제 능력은 일부 감소했다. 이러한 결과는 벤질리덴아세톤과 벤질리덴아세톤 유도체는 면역작용에 관여하는 $PLA_2$와 PO의 두 가지 효소 활성을 억제하며, 배추좀나방에 대한 Bt 병원성을 제고시켰으며, 식물병원성 진균에 대한 항균제로서의 개발 가능성을 제시하고 있다.