• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2976-2980
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• 2012

Nitrile-forming eliminations from (E)-2,4-$(NO_2)_2C_6H_2CH=NOC_6H_4-2-X-4-NO_2$ (1a-e) promoted by $R_3N$ in MeCN have been studied kinetically. The reactions are second-order and exhibit Br$\ddot{o}$nsted ${\beta}$ = 0.83-1.0 and ${\mid}{\beta}_{lg}{\mid}$ = 0.41-0.46. The results have been interpreted in terms of highly E1cb-like transition state with extensive $C_{\beta}$-H bond cleavage and limited $N_{\alpha}$-OAr bond cleavage. Comparison with existing data reveals that the structure of the transition state changes from E2-central to highly E1cb-like either by the change of the ${\beta}$-aryl group from Ph to 2,4-dinitrophenyl under the same condition or by the base-solvent system variation from $EtO^-$-EtOH to $Et_3N$-MeCN for a given substrate (1a-e).

• 생약학회지
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• 제29권3호
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• pp.209-216
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• 1998

In the course of phytochemical studies of Rumex acetosella L. (Polygonaceae), the MeOH extract of the whole plants was fractionated with $CH_2Cl_2$ and $H_2O$, and the $CH_2Cl_2$ layer was fractionated again with 90% MeOH and hexane. Whereas $H_2O$ layer was fractionated with EtOAc and then with n-BuOH again. By repeated column chromatography, compound 1 was isolated from the 90% MeOH fraction, compounds 1, 2, 3, 4 and 5 were from the ethylacetate fraction, and compound 5 was from the n--BuOH fraction. On the basis of physico-chemical, spectroscopic evidences and in comparison with authentic samples, the structures of them were confirmed to emodin, citreorosein, $chrysophanol-8-O-{\beta}-D-glucopyranoside$, luteolin and $luteolin-7-O {\beta}-D-glucopyranoside$.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2909-2912
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• 2009

The amines studied in this study are less reactive toward ethyl propiolate (3) in MeCN than in H$_2$O although they are 7 to 9 pK$_a$ units more basic in the aprotic solvent. The reactivity of morpholine and deuterated morpholine toward 3 is found to be identical, indicating that proton transfer occurs after rate-determining step (RDS). The fact that kinetic isotope effect is absent excludes a stepwise mechanism in which proton transfer occurs in RDS as well as a concerted mechanism in which nucleophilic attack and proton transfer occur concertedly through a 4-membered cyclic transition state (TS). Thus, the reactions have been concluded to proceed through a stepwise mechanism in which proton transfer occurs after RDS. Brønsted-type plots are linear with small ${\beta}_{nuc}$ values, i.e., ${\beta}_{nuc}$ = 0.29 in H$_2$O and ${\beta}_{nuc}$ = 0.51 in MeCN, indicating that bond formation is not advanced significantly in RDS. The small ${\beta}_{nuc}$ value also supports the conclusion drawn from the study of kinetic isotope effect.

• The Korean Journal of Physiology and Pharmacology
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• 제3권2호
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• pp.165-174
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• 1999

We explore the question of whether adenosine 5'-triphosphate (ATP) acts as an excitatory neurotransmitter in guinea-pig gastric smooth muscle. In an organ bath system, isometric force of the circular smooth muscle of guinea-pig gastric antrum was measured in the presence of atropine and guanethidine. Under electrical field stimulation (EFS) at high frequencies (＞20 Hz), NO-mediated relaxation during EFS was followed by a strong contraction after the cessation of EFS (a 'rebound-contraction'). Exogenous ATP mimicked the rebound-contraction. A known $P_{2Y}-purinoceptor$ antagonist, reactive blue 2 (RB-2), blocked the rebound-contraction while selective desensitization of $P_{2Y}-purinoceptor$ with ${\alpha},{\beta}-MeATP$ did not affect it. ATP and 2-MeSATP induced smooth muscle contraction, which was effectively blocked by RB-2 and suramin, a nonselective $P_2-purinoceptor$ antagonist. Particularly, in the presence of RB-2, exogenous ATP and 2-MeSATP inhibited spontaneous phasic contractions, suggesting the existence of different populations of purinoceptors. Both the rebound-contraction and the agonist-induced contraction were not inhibited by indomethacin. The rank orders of agonists' potency were 2-MeSATP > ATP ${ge}$ UTP for contraction and ${\alpha},{\beta}-MeATP\;{\ge}\;{\beta},{\gamma}-MeATP$ for inhibition of the phasic contraction, that accord with the commonly accepted rank order of the classical $P_{2Y}-purinoceptor$ subtypes. Electrical activities of smooth muscles were only slightly influenced by ATP and 2-MeSATP, whereas ${\alpha},{\beta}-MeATP$ attenuated slow waves with membrane hyperpolarization. From the above results, it is suggested that ATP acts as an excitatory neurotransmitter, which mediates the rebound-contraction via $P_{2Y}-purinoceptor$ in guinea-pig gastric antrum.

• Tuberculosis and Respiratory Diseases
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• 제70권5호
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• pp.405-415
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• 2011

Background: In an effort to find alternative therapeutic agents to prevent excessive fibrosis as a sequela to complicated parapneumonic effusion or empyema, we examined the effect of tissue plasminogen activator (tPA) as a fibrinolytic agent combined with talc or transforming growth factor (TGF)-${\beta}1$ in a human pleural mesothelial cell line, MeT-5A. Methods: MeT-5A cells were stimulated with various doses of talc, doxycycline or TGF-${\beta}1$ for 24 h and then were treated with tPA for an additional 24 h. Cell viability was measured by MTT assay. The production of interleukin (IL)-8 and vascular endothelial growth factor (VEGF) in the culture supernatants was measured by ELISA. Real-time PCR was carried out for measurement of type I collagen mRNA. Results: MeT-5A cells treated with talc showed a dose-dependent increase in production of IL-8. Talc also increased production of type I collagen mRNA at low doses, but talc did not influence the induction of VEGF. Addition of tPA to talc-stimulated cells showed further increases in the production of IL-8, but tPA did not influence the production of VEGF or type I collagen mRNA. TGF-${\beta}1$ increased the production of both VEGF and collagen type I mRNA, both of which were effectively inhibited by additional tPA treatment in MeT-5A cells. Conclusion: TGF-${\beta}1$ is a potent inducer of collagen synthesis without induction of IL-8 in MeT-5A cells. Addition of tPA after TGF-${\beta}1$ stimulation inhibited further fibrosis by direct inhibition of collagen mRNA synthesis as well as by inhibition of VEGF production.

• 대한약침학회지
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• 제22권4호
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• pp.248-252
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• 2019

Objectives: The aim of the present work is evaluating the special effects of Urtica Dioica and Lamium Album on the serum level of K-Ras and GSK-3 beta in diabetic rats. Methods: In the present experimental study, 32 male Wistar rats randomly divided into 4 groups (Group I: normal control rats; receiving daily PBS, Group 2: diabetic control rats; receiving single dose of streptozotocin (60 mg/kg) and daily PBS, Group 3: Diabetic rats treated with 100 mg/kg of hydroalcoholic extract of the U. dioica, Group 4: Diabetic rats treated with 100 mg/kg of hydroalcoholic extract of L. Album. Diabetes-induced by an intraperitoneal injection of streptozotocin (60 mg/ kg). On the 14 th day of treatment, the weight, fasting blood sugar (FBS) and on 28 th day blood glucose, K-Ras and GSK3 beta was measured. Results: In diabetic group blood GSK- 3 beta increase in comparison to control group (P < 0.05), also blood K-Ras decrease in the diabetic group (P < 0.05). Both extracts reduced GSK-3 beta level, however, this reduction was only statistically significant by U.dioica (P < 0.05). Compared to diabetic group, blood K-Ras level increased by both extract (P < 0.05). Also diabetes induction increase blood glucose levels and both extracts decrease its level significantly (P < 0.05).there is no significant differences among both extract effects on blood glucose, and K-Ras. Conclusion: For the first time shown that both extracts by regulating GSK-3 beta and K-Ras improve blood glucose level. More studies are needed to determine all the effects of these herbs.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.186-186
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• 1998

Persicaria lapathifolia Gray (Polygonaceae) is a common weed in Korea. This plant and other Persicaria species including P. orientale and P. pubescens have been used as an analgesic and stomachic as well as for the treatment of rheumatoid arthritis and malaria. During the screening program of plant extracts, MeOH extract of P. scabrum showed anticomplement activity and the MeOH extract was partitioned with hexane, chloroform, ethyl acetate, and buthanol. EtOAc fraction showed strong activity and activity guided separation yielded eight flavonoids. Two known galloylated and a novel ferulloylated flavonoid glycosides showed strong anticomplement activity. Other flavonoid glycosides, kaempferol 3-O-${\alpha}$-$\sub$L/-arabinopyranoside, kaempferol 3-O-${\beta}$-$\sub$D/-glucopyranoside, kaempferol 3-O-${\beta}$-$\sub$D/-galactopyranoside, quercetin 3-O-${\alpha}$-$\sub$L/-arabinopyranoside, quercetin 3-O-${\beta}$-$\sub$D/-glucopyranoside, quercetin O-${\beta}$-$\sub$D/-galactopyranoside did not showed anicomplement activity.

• 수산해양기술연구
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• 제27권4호
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• pp.328-331
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• 1991

LiF(Mg,Cu,Na,Si) 형광체의 ${\gamma}$선과 $\beta$선에 대한 TSEE 특성을 조사하였다. 상(60)Co ${\gamma}$선에 대한 감도는 약 450 counts/mR이었고, 여러 가지 $\beta$선에 대한 TSEE 에너지 의존성은 $\beta$입자의 평균에너지 0.02MeV에서 0.8MeV 사이에서 $\pm$10%이었다. 그리고 제작된 형광체 앞면에 7mg.cm 상(-2)의 인체 등가물질을 두 면 입사 $\beta$입자의 에너지에 무관하게 피부 흡수 선량을 측정할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1921-1924
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• 2011

Nitrile-forming eliminations from $(E)-2,4,6-(NO_2)_3C_6H_2CH=NOC_6H_4-2-X-4-NO_2$ (1) promoted by $R_3NH/R_3NH^+$ in 70 mol % MeCN(aq) have been studied kinetically. When X = $NO_2$, the reactions exhibited second-order kinetics as well as Br$\"{o}$nsted ${\beta}$ = 0.63 and ${\mid}{\beta}_{lg}{\mid}$ = 0.34-0.46, and an E2 mechanism is evident. As the leaving group was made poorer (X = H, Cl, and $CF_3$), Br$\"{o}$nsted ${\beta}$ value increased from 0.63 to 0.85-0.89 without much change in the ${\mid}{\beta}_{lg}{\mid}$ value E2, indicating that structure of the transition state changed to an E1cb-like with extensive $C_{\beta}-H$ bond cleavage, significant negative charge development at the ${\beta}$-carbon, and limited $C_{\alpha}$-OAr bond cleavage.

• 한국산림과학회지
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• 제77권4호
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• pp.421-428
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• 1988

본(本) 연구(硏究)는 표본점(標本點)의 크기와 형태에 따른 작업(作業) 시간을 비교분석하고 효율성(效率性)을 검정(檢定)하여 적정 표본점 크기와 형태를 선택(選擇)하기 위한 것으로, 지형이 평탄(平坦)하고 임목생립(林木生立)이 고르게 분포된 2개 임분(林分)을 택하여 각각 198 plot, 306 plot를 조사하였다. 표본점 설치방법의 시간상 유리함을 알아보기 위하여 방형(方形)에서는 Blumeleiss-$Me{\beta}$ trommel을 이용하는 방법과 줄자를 이용하는 방법을 비교하였다. 1. 방형(方形)에서는 직접 4면 설치법이 대각선으로 설치하는 방법보다 시간적으로 유리하였다. 2. 원형(圓形)에 있어서는 Blumeleiss-$Me{\beta}$ trommel을 이용한 방법이 줄자를 이용하나 방법보다 유리(有利)하였다. 3. 원형(圓形) 표본점(標本點)이 방형(方形) 표본점(標本點)에 비해 시간적으로 유리하였다. 특히 작은 표본점에서는 원형이 방형에 비해 2배 정도 유리하였지만, 점차 면적이 커지면서 원형 표본점의 시간적(時間的) 유리성(有利性)이 줄어들었다.