• Archives of Pharmacal Research
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• 제9권2호
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• pp.81-86
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• 1986

The effect of imperatorin on hepatic microsomal mixed function oxidases (MF0) was investigated. On acute treatment, imperatorin (30 mg/kg, i.p) caused a significant reduction in activities of hepatic aminopyrine N-demethylase, hexobarbital hydroxylase and aniline hydroxylase as well as cytochrome p0450 content in rats and mice. Kinetic studies on rat liver enzymes revealed that imperatorin appeared to be a competitive inhibitor of aminopyrine N-demethylase (Ki,0.007 mM), whereas a non-competitive inhibitor of hexobarbital hydroxylase (Ki, 0.0148 mM). Imperatorin also inhibited non-competitively aniline metabolism (Ki 0.2 mM). Imperatorin binds to phenobarbital-induced cytochrome p-450 to give a typical type 1 binding sepctrum (max. 388nm, min 422 nm). Multiple administrations of imperatorin (30 mg/kg. i. p. daily for 7 days) to mice shortended markedly the duration of hexobarbital narcosis and increased activities of hepatic aminopyrine N-demethylase and hexobarbital hydroxylase and the level of cytochrome p-450 where as aniline hydroxylase activity was unaffected.

• Corrosion Science and Technology
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• 제12권2호
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• pp.65-78
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• 2013

The present investigation deals with the corrosion inhibition of mild steel in 1M $H_2SO_4$ with 1, 4-dihydro pyridine and its derivatives prepared using microwave activation method. The synthesis of inhibitor was confirmed by IR spectra. The effect of 1, 4-dihydropyridine derivatives on the corrosion inhibition of mild steel in 1M $H_2SO_4$ was studied using weight loss and electrochemical polarization techniques. Influence of temperature (303-333K) and synergistic effect of halide ions ($I^-$, $Br^-$ and $Cl^-$) on the inhibition behaviour was also studied. Corrosion products on the metal surface were analyzed by scanning electron microscopy (SEM) and a possible mechanism of inhibition by the compounds is suggested. Thermodynamic parameters were calculated using weight loss data in order to elaborate the mechanism of corrosion inhibition. Polarization measurements revealed that the studied compounds acted as mixed type inhibitor but slightly anodic in nature. Electrochemical impedance measurements revealed that the compounds were adsorbed onto the carbon steel surface and the adsorption obeyed the Langmuir adsorption isotherm. The synergistic effect of halide ions on the IE increases with increase in concentration. The IE obtained from atomic absorption spectrophotometric studies was found to be in good agreement with that obtained from the conventional weight loss method. SEM revealed the information of a smooth, dense protective layer in presence of the inhibitors.

• International Journal of Industrial Entomology and Biomaterials
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• 제9권1호
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• pp.29-33
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• 2004

Low molecular weight silk fibroin (LMSF), which was prepared by hydrolysis of silk fibroin using high-temperature and high-pressure method, was found to inhibit the oxidation of L-3,4,-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase (EC 1.14.18.1). LMSF contained mostly free amino acids such as L-glycine, L-alanine, and L-serine and oligopeptides, mainly glycine-alanine dimer. As a result of analyzing the inhibition kinetics from Lineweaver-Burk plots, L-glycine and glycine-alanine dimer showed noncompetitive behavior while uncompetitive behavior was observed in L-alanine, and L-serine. When weight percent concentration of ${ID_50}$ was compared, L-glycine was most effective on the inhibition and LMSF was also good enough for the inhibition effect of tyrosinase activity. LMSF showed a mixed-type inhibition and the inhibitory mechanism of LMSF might be caused by free amino acids and oligopeptides. As a result of spectroscopic observation with time, initial rate of increase of DOPAchrome decreased remarkably and the time to reach maximum absorbance increased as an increase of the concentration of L-glycine, meaning that L-glycine made itself mainly responsible for the formation of chelate with ${Cu^2+}$ in tyrosinase. However, in case of L-alanine, L-serine, and especially glycine-alanine dimmer, the production of DOPAchrome after an arrival at maximum absorbance decreased, indicating the production of adducts through the reaction with DOPAquinone.

• Journal of Korean Dental Science
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• 제5권1호
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• pp.7-12
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• 2012

Purpose: To examine the antibacterial effectiveness of silver nanoparticles (SNP) mixed with commercial orthodontic adhesives. Materials and Methods: SNP was prepared by dissolving silver perchlorate in an organic solvent and reducing it with ultraviolet radiation. SNP was then mixed with four commercial orthodontic adhesives (Light Bond, Blugloo, Transbond XT, and Fuji Ortho LC) (0.05 wt %), which were then formed into disc-shape specimens ($8.0mm{\times}3.0mm$). Commercial orthodontic adhesives containing no SNP were used as the control groups. Specimens of the four experimental and four control groups were incubated with streptococcus mutans and the medium turbidity was assessed at 3, 6, 9, 12, and 24 hours after incubation. The agar diffusion test was also performed to examine the growth inhibition zone of these groups. The data were statistically analyzed using a Wilcoxon rank sum test and t-test with a Bonferroni's correction (P<0.05). Result: The SNP containing groups had a superior antibacterial effect compared to the control groups. In the agar diffusion test, the control groups without SNP did not produce an inhibition zone, whereas the SNP containing groups showed inhibition zone of 10~13 mm. Conclusion: The incorporation of SNP into orthodontic adhesives can inhibit cariogenic bacterial growth.

• 한국환경보건학회지
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• 제16권1호
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• pp.45-53
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• 1990

To investigate the effect of cultural condition on the aflatoxin production of Aspergillus flayus ATCC 15517, mixed culture with Aspergillus niger, better kind of media and size of Cultural vessels were examined. YES medium was better than SLS medium for this study. Small scale test tube culture was showed the possibility to simply examine the growth, total acidity, pH and aflatoxin production during cultivation, and also could reduce the second contamination of aflatoxin B1 from large scale broth cultured. Especially ELISA method is simple, sensitive and specific and therefore well suited to small scale of test tube culture. Mixed culture significantly reduced the aflatoxin production of Aspergillus fiavus ATCC 15517 and showed almost 95% inhibition of that level during the incubtation.

• Asian-Australasian Journal of Animal Sciences
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• 제18권2호
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• pp.282-295
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• 2005

The processing of dietary lipids can be distinguished in several sequential steps, including their emulsification, hydrolysis and micellization, before they are absorbed by the enterocytes. Emulsification of lipids starts in the stomach and is mediated by physical forces and favoured by the partial lipolysis of the dietary lipids due to the activity of gastric lipase. The process of lipid digestion continues in the duodenum where pancreatic triacylglycerol lipase (PTL) releases 50 to 70% of dietary fatty acids. Bile salts at low concentrations stimulate PTL activity, but higher concentrations inhibit PTL activity. Pancreatic triacylglycerol lipase activity is regulated by colipase, that interacts with bile salts and PTL and can release bile salt mediated PTL inhibition. Without colipase, PTL is unable to hydrolyse fatty acids from dietary triacylglycerols, resulting in fat malabsorption with severe consequences on bioavailability of dietary lipids and fat-soluble vitamins. Furthermore, carboxyl ester lipase, a pancreatic enzyme that is bile salt-stimulated and displays wide substrate reactivities, is involved in lipid digestion. The products of lipolysis are removed from the water-oil interface by incorporation into mixed micelles that are formed spontaneously by the interaction of bile salts. Monoacylglycerols and phospholipids enhance the ability of bile salts to form mixed micelles. Formation of mixed micelles is necessary to move the non-polar lipids across the unstirred water layer adjacent to the mucosal cells, thereby facilitating absorption.

• The Korean Journal of Physiology and Pharmacology
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• 제2권2호
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• pp.261-269
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• 1998

Concomitant administration of a single acute dose of ethanol (4 g/kg) protected mice from the hepatocellular injury observed upon administration of a large dose of acetaminophen (400 mg/kg). This was evidenced by the normal histological appearances of liver sections and by the lowered serum aminotransferase activities in mice treated with ethanol and acetaminophen together. In the mice treated with acetaminophen alone, along with the hepatic necrosis, the hepatic microsomal aminopyrine N-demethylase activity was decreased. However, co-administration of ethanol prevented this acetaminophen dependent inhibition on the microsomal mixed function oxidase activity. Pharmacokinetic studies indicated that the concentration of un-metabolized drug in the blood was increased in the ethanol treated mice. Furthermore, upon co-administration of ethanol, although the biliary levels of acetaminophen metabolites (glucuronide, sulfate and cysteine conjugates) were decreased, the level of unmetabolized acetaminophen was increased. Our findings suggest that co-administration of an acute dose of ethanol reduces the degree of hepatocellular necrosis produced by a large dose of acetaminophen and this ethanol dependent protection is, in major part, afforded by suppression of the hepatic microsomal mixed function oxidase activity catalyzing the metabolic activation of acetaminophen.

• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.454-458
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• 1995

Inhibiting action of semicarbazide, thiosemicarbazide, sym. diphenylcarbazide towards corrosion of zinc in hydrochloric acid has been investigated. The rate of corrosion depends on the nature of the inhibitor and its concentration. The values of inhibition efficiency from, weight loss, thermometric measurements are in good agreement with those obtained from polarization studies. From the polarization studies, the inhibitors used act as mixed absorption type inhibitors, increased adsorption resulting from an increase in the electron density at the reactive C=S and C=O groups and N-atoms. The thermodynamic parameters of adsorption obtained using Bockris-Swinkels adsorption isotherm reveal a strong interaction of these carbazides on zinc surface.

• 한국잡초학회지
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• 제15권3호
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• pp.232-237
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• 1995

일년생(一年生) 방제용(防除用) 제초제(除草劑) 8종과 혼합(混合)된 azimsulfuron의 벼와 피의 지상부(地上部) 및 뿌리 생육(生育)에 끼치는 영향(影響)을 조사(調査)하였다. 벼 지상부는 일년생(一年生) 제초제(除草劑) 혼합처리(混合處理)가 azimsulfuron 단독(單獨) 처리(處理)보다 큰 생육억제(生育抑制) 효과(效果)를 나타내었으나, 어느 경우에도 약해(藥害) 경감(經減) 효과(效果)는 없었다. 벼 뿌리에 대한 약해 경감 효과는 10ppm 이상의 azimsulfuron에 혼합(混合)된 dimepiperate, molinate 및 dymron 에서만 나타났다. 벼 지상부(地上部) 및 뿌리의 생육억제(生育抑制) 효과(效果)는 직쇄상(直鎖狀) 탄화수소(炭化水素) 치환체(置換體)인 esprocarb나 thiobencarb의 혼합(混合)이 환상(環狀) 탄화수소(炭化水素) 치환체(置換體)인 dimepiperate나 molinate의 혼합(混合)에서 보다 크게 나타났다. Azimsulfuron에 대한 일년생(一年生) 제초제(除草劑)의 혼합(混合)으로 피의 지상부(地上部) 및 뿌리 생육억제(生育抑制) 는 azimsulfuron 단독(單獨) 처리(處理)에 비하여 크게 증대(增大) 되었다.

• 대한화학회지
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• 제43권4호
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• pp.461-468
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• 1999

Acetolactate synthase (ALS)는 가지를 가진 필수아미노산 Val, Leu, Ile의 생합성 과정에서 공통적으로 작용하는 효소이다. ALS는 서로 구조적 유사성이 없는triazolopyrimidine, imidazolinone,sulfonylurea, 그리고 pyrimidyl-oxy-benzoate 제초제들의 공통적인 작용 표적이다. 보리로부터 부분 정제한 ALS를 이용하여 새로이 합성한 triazolopyrimidine sulfonamide 유도체들의 저해 활성을 측정하였다. 활성을 가진 유도체들의 $IC_{50}$ 값은 0.5nM∼8${\mu}M$ 범위였으며, 그 중에서 탁월한 저해 활성을 갖는 것은 TP1과TP2 유도체로 $IC_{50}$ 값은 각각 0.5 nM과 1.6 nM이였다. 이 저해제들은 기존의 상품화된 제초제인 Metosulam ($IC_{50}$;3.6 nM), Flumetsulam ($IC_{50}$;126 nM), 그리고 Cadre ($IC_{50};4 {\mu}M$)에 비해 보리 ALS에 대한 저해 활성이 보다 우수하였다. 보리 ALS에 대한 TP2의 저해 활성은 반응시간이 증가함에 따라 증가하였고, 혼합형 저해 유형을 보였다. TP2와 imidazolinone 계열의 제초제인 Cadre, 그리고 되먹임(feedback) 저해제인 Leu에 대한 이중저해 (dual inhibition) 실험 결과 TP2와 Cadre의 경우는 평행한 반응속도론적 형태가 그러나 TP2와 Leu의 경우는 한 점에서 만나는 반응속도론적 헝태가 얻어졌다. 이는 TP2와 Cadre의 결합 부위가 최소한 부분적으로 중복되고 있음을 시사한다. Cys 잔기에 대한 화학적 변형은 TP2와 Cadre의 결합에는 영향을 미치지 않으나, Leu의 결합에는 영향을 미쳤다.