• Title, Summary, Keyword: inhibitors

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The Physicochemical Properties of $\alpha$-Amylase Inhibitors from Black Bean and Naked Barey in Korea (한국산 검정콩 및 쌀보리 $\alpha$-Amylase 저해물질의 이화학적 특성)

  • 심기환;문주석;배영일
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.27 no.3
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    • pp.367-375
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    • 1998
  • The physicochemical properties of the $\alpha$-amylase inhibitors from black bean and naked barley is Korea were investigated. Preincubation time for maximum inhibition was 30min and no activity change was seen after that time. Optimum pH of the $\alpha$-amylase inhibitors from the black bean and naked barley was pH 7.0 and the inhibitory activities were stable in the range of pH 6.0~8.0 in both phosphate and Tris-HCI buffer solutions. Both inhibitors maintained more than 50% of activity after incubation for 17 min at 7$0^{\circ}C$. The inhibitors from the black bean and naked barley maintained more than 50% of activities after treatment for 40 min and 30 min with pepsin, and 30 min and 50 min with trypsin, respectively. Both inhibitors functioned via a noncompetitive mechanism and were active against porcine pancreatic and human salivary $\alpha$-amylases. The activities of both inhibitors were linear for the ionic stength ranging from 0 to 0.9. The addition of 70 mM maltose to the reaction mixture caused a maximum increase in the relative activities of both inhibitors, but it did not affect the dissociation of the EI complex. The activities of both inhibitors were significantly enhanced by adding 1mM of K+ or Mg2+.

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Vasorelaxant properties of cyclic nucleotide phosphodiesterase inhibitors in rat aorta (흰쥐 대동맥에서 cyclic nucleotide phosphodiesterase 억제제들의 혈관 이완 특성)

  • Kang, Hyung-sub;Choi, Cheol-ho;Kim, Jin-shang
    • Korean Journal of Veterinary Research
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    • v.43 no.4
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    • pp.615-624
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    • 2003
  • Vascular smooth muscle relaxation is modulated by an increase in cGMP subsequent to nitric oxide (NO) production by endothelial cells. The effects of cAMP and cGMP phosphodiesterase (PDE) inhibitors were investigated in phenylephrine-precontracted rat aorta rings by using the specific inhibitors of PDE I, III, IV and V as relaxing agents (calmodulin-activated PDE inhibitors, IBMX and $W_7$, type I; cAMP-specific PDE inhibitors, milrinone, type IV; Ro 20-1724, type III and cGMP-specific PDE inhibitor, zaprinast, type V). All the PDE inhibitors produced a concentration-dependent relaxation in the ring with intact endothelium (+E). Except for milrinone, all the PDE inhibitors-induced relaxations were inhibited by removal of extracellular $Ca^{2+}$, $N^G$-nitro-L-arginine, $N^G$-nitro-L-arginine methyl ester, methylene blue (MS) or nifedipine. The specific PDE I and PDE IV inhibitors both produced endothelium-independent relaxations which were inhibited by MS in -E rings. However, zaprinast had no effect in -E rings. Except for milrinone, sodium nitroprusside (a NO donor)-induced relaxation was significantly augmented by all PDE inhibitors in +E rings. The results suggest that I) the vasorelaxant properties of IBMX, $W_7$, Ro 20-1724 and zaprinast are dependent on endothelium or on interaction with $Ca^{2+}$ regulation, 2) each PDE is differently distributed in vascular tissues (endothelial and smooth muscle cells), 3) the vasodilations of PDE inhibitors are due to the increase of cAMP and cGMP formation through inhibition of cAMP- and cGMP-PDE and 4) the vasodilation action of milrinone does not involve in endothelial-cyclic nucleotide system.

Influence of Grain Growth Inhibitors and Co in Nano WC Materials (나노 텅스텐 카바이드 재료 내 입성장 억제제와 코발트의 영향)

  • Lim, Hyung Sup;Hur, Man Gyu;Kim, Deug Joong;Yoon, Dae Ho
    • Journal of the Korean Ceramic Society
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    • v.51 no.5
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    • pp.442-446
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    • 2014
  • Influences of Co and inhibitors from nano-sized WC materials were observed in the sintering process. VC and $Cr_3C_2$ were used as inhibitors. The crystal structure and surface images of sintered nano-sized WC materials, as functions of Co and inhibitors, were evaluated by XRD and FE-SEM analyses. The relative densities of sintered nano-sized WC materials did not change even with increased quantity of Co and increased temperature. The density of sintered nano-sized WC materials with inhibitors was lower than that of sintered nano-sized WC materials without inhibitors. No difference in hardness due to change of inhibitors was found.

Evaluation of Hydrogen Sulfide Corrosion Inhibitors for Wet Gas Pipeline Steel

  • Huy, Vu Dinh;Thoa, Nguyen Thi Phuong;Phong, Tran Quoc;Hoang, Nguyen Thai
    • Corrosion Science and Technology
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    • v.4 no.3
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    • pp.95-99
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    • 2005
  • Wheel test and potentiodynamic polarization methods were used to evaluate the relative effectiveness of some hydrogen sulfide corrosion inhibitors for the wet gas pipeline API 5L grade X 65 steel. Five commercially corrosion inhibitors have been studied in the deoxygenated produced water solutions containing 10 ppm and 100 ppm of hydrogen sulfide. Based on the experiment results the steel corrosion inhibition mechanism in discussed and two most effective corrosion inhibitors are selected.

Classification According to Site of Action of Paddy Herbicides Registered in Korea (국내 수도용 제초제의 작용기작별 분류)

  • Park, Jae-Eup;Kim, Sang-Su;Kim, Young-Lim;Kim, Min-Ju;Ha, Heun-Young;Lee, In-Yong;Moon, Byung-Chul;Ihm, Yang-Bin
    • Weed & Turfgrass Science
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    • v.3 no.3
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    • pp.165-173
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    • 2014
  • This review study was conducted to recommend the effective use of herbicide mixtures in Korea. The herbicide ingredients by Herbicide Resistancce Action Committee (HRAC) was classified into 23 groupes according to the mode of action (acetyl CoA carboxylase inhibitors, acetolactate synthase, photosystem I and II inhibitors, protoporphyrinogen oxidase inhibitors, carotenoid biosynthesis inhibitors, enolpyruvyl shikimate-3-phosphate synthase inhibitors, glutamine synthetase inhibitors, dihydropteroate synthetase inhibitors, mitosis inhibitors, cellulose inhibitors, oxidative phosphorylation uncouplers, fatty acid and lipid biosynthesis inhibitors, synthetic auxins, auxin transport inhibitors and potential nucleic acid inhibitors or non-descript mode of action). The rice herbicide mixtures registered in Korea were classified based on the guideline of HRAC. Accordingly, such a classification system for resistance management can help to avoid continuous use of the herbicide having the same mode of action in the same field.

COX-inhibitors down-regulate TCDD-induced cyp1a1 activity in C57BL/6 mouse and Hepa- I cells.

  • Bang Syrieo;Jung, Cho-Min;Yhong, Sheen-Yhun
    • Proceedings of the Korea Society of Environmental Toocicology Conference
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    • pp.173-173
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    • 2002
  • In order to understand the mechanism of action of TCDD, we have examined the effect of COX-inhibitors on cyp1a1 activity. We observed the effect of COX-inhibitor on EROD activity in C57BL/6 mouse in vovo. And we also evaluated the effect of COX-inhibitors on cyp1a1 mRNA, mouse cyp1a1 promoter activity and EROD activity in Hepa cell. When Aspirin were pretreated with 3MC in vivo, the EROD activity that was stimulated by 3MC was inhibited. And Pretreatment of Aspirin, Celecoxib, Nimesulide and other several Cox-inhibitors in vitro, inhibited the TCDD stimulated EROD activity and Luciferase acitivity. In case of cyp1a1 mRNA level, Nimesulide and SB100 were able to decrease cyp1a1 mRNA that was stimulated by TCDD, but other tested COX-inhibitors were not decrease. We don't know this different result exactly. For the action of Cox-inhibitors on the Cyp1a1, it seems to be important to do pretreatment of these chemicals as apposed to TCDD. In this study, thus, we have suggested that COX-inhibitors such as aspirin, celecoxib, Nimesulide and other several Cox-inhibitors decrease the TCDD induced Cyp1a1.

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Effect of Corrosion Inhibitor for Reinforcing Steel in Concrete Containing Chlorides (염화물을 함유한 콘크리트 중의 철근방식을 위한 방청제의 효과)

  • 문한영;김성수
    • Magazine of the Korea Concrete Institute
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    • v.10 no.6
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    • pp.325-333
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    • 1998
  • Under the seawater environment, the reinforced concrete structure is deteriorated due to physical and chemical attacks. The main deterioration mechanism is the chloride corrosion of reinforcing steel. The corrosion inhibitors have been used to protect the rebars from corrosion which are susceptible to chlorides in concrete. However, there is not clear conclusion about corrosion inhibitors yet. In this study, it is made the accelerated experiment with 3 kinds of corrosion inhibitors for various chloride ingresses. It is estimated corrosion inhibitors that inhibitors by Half-Cell Potential, corrosion area ratio and weight loss ratio. It is concluded that inhibitors are not effective to corrosion inhibition for excessive chloride ingress. However, the effect of inhibition is directly proportional ot contents of corrosion inhibitors in some chloride ingress.

Effects of Inhibitors (DFMO, DFMA) on Polyamine Synthetic Enzymes (ADC, ODC) during Ovarian Development of the Tobacco Budworm, Helicoverpa assulta (담배나방의 난소발생시 폴리아민 합성효소에 미치는 저해제의 효과)

  • 우장환;김문익;김선희;이형철;정성은
    • Journal of the Korean Society of Tobacco Science
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    • v.21 no.1
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    • pp.26-35
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    • 1999
  • Effects of $\alpha$-difluoromethylornithine (DFMO) and $\alpha$-difluoromethylarginine (DFMA), inhibitors of polyamine syntheic enzymes (ornithine decarboxylase, arginine decarboxylase), on ovary were investigated during pupal-adult development of Helicoverpa assulta. Two inhibitors (DFMO, DFMA) showed definite inhibition effects on ovarian development. The inhibition effect on ovaries weight was more marked in DFMA-injection than that observed in DFMO-injection. Two inhibitors (DFMO, DFMA) gave rise to a peculiar decrease in ornithine decarboxylase (ODC) or arginine decarboxylase (ADC) activity in ovaries, 72 hrs (5-day old pupa) post injection. However, DFMO clearly exhibited supression of ODC activity after 96 hrs (6-day old pupa). In addition, two inhibitors (DFMO, DFMA) diminished putrescine content in the ovary. The spermidine level was slightly decreased by each injection of the inhibitors. However, two inhibitors (DFMO, DFMA) raised the spermine content at certain developmental stages in the ovary. Although the effect of DFMA was less severe, two inhibitors (DFMO, DFMA) caused not only an overall delay in ovarian development, but also abnormalities in cellular differentiation. Noted effects in the pupal ovary were the appearance of irregular nurse cells and partial destruction of follicle epidermal cells. Adult ovary showed rapid degradation of nurse cells, a reduction in the number of follicle epidermal cells and immature oocytes that had a low yolk content.

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The Stimulatory Effect of PDE Inhibitors on $PGE_2$-Induced Osteoclastogenesis (PDE 저해제에 의한 $PGE_2$의 파골세포 분화 유도 증강효과)

  • No, A-Long-Sae-Mi;Yim, Mi-Jung
    • YAKHAK HOEJI
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    • v.51 no.4
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    • pp.235-238
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    • 2007
  • To determine the regulatory roles of phosphodiesterase (PDE) inhibitors on $PGE_2$-induced osteoclastogenesis, we investigated the effect of PDE inhibitors on osteoclast formation in the presence of $PGE_2$. Among PDE isozyme specific inhibitors, milrinone, a selective PDE3 inhibitor, and rolipram, a specific PDE4 inhibitor, increased $PGE_2$-induced osteoclast formation in cocultures of mouse bone marrow cells and osteoblasts. To verify that whether the PDE3 and PDE4 inhibitors act indirectly on osteoblasts, we measured the concentration of intracellular cAMP in osteoblasts. Treatment of milrinone or rolipram increased $PGE_2$-stimulated cAMP levels in osteoblasts. Furthermore, northern blot analysis revealed that the PDE3 and PDE4 inhibitors works synergistically with $PGE_2$ to increase the expression of TRANCE mRNA in osteoblasts. On the contrary, the PDE3 and PDE4 inhibitors did not augment the number of osteoclasts differentiated from bone marrow cells by $PGE_2$. In conclusion, the stimulation of $PGE_2$-induced osteoclast formation by the PDE3 and PDE4 inhibitors are attributable to their indirect effect on osteoblasts, not to their direct effect on bone marrow-derived osteoclast precursors.

The Effect of Corrosion Inhibitor on Corrosion Control of Copper Pipe and Green Water Problem

  • Lee, Ji-Eun;Lee, Hyun-Dong;Kim, Gi-Eun
    • Environmental Engineering Research
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    • v.17 no.1
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    • pp.17-25
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    • 2012
  • Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.