• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.179-183
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• 1981

An extracellular chitinase was purified from the culture fluid of Streptomyces sp. 115-5, and its inhibition mechanism by end product was studied. The activity of chitinase was suppressed by the reducing sugar as the reaction proceeded, and the activity was inhibited by the addition of D-glucose. Besides D-glucose, the rate of chitin hydrolysis was inhibited by D-glucuronic acid, D-sorbitol and D-xylose in the reaction system of the enzyme. it was found that the hydroxyl groups at the C-2, C-3 and C-4 position of D-glucose molecule play an important role in the inhibition of the chitinase activity. D-glucose was found to inhibit the enzyme activity by mixed type of competitive and non-competitive mode.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.268-284
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• 2003

Nor-aporphine derivatives have been discovered which interfere with the flux of Calcium into and out of the cell interior. It has been shown that adrenergic antagonists that block the Calcium exchange lead to an inhibition of Protein kinase C activity, thus blocking tyrosinase activation. Di-acetyl-dimethoxy-methyl-nor-aporphine is a semi-synthetic molecule of natural origin with very high potency. On B16 melanocytes as well as in normal human melanocytes the decrease in melanin synthesis reaches -50％ at a level of 40 ppm in the culture medium. On a molar concentration basis, this is 50 to 70 times stronger than Kojic acid inhibition. Yet, the cell viability is not affected. Reversibility studies show that after washing out of the active compound, melanogenesis returns to normal levels. Possible mechanisms of the activity are discussed. Tests carried out on SkinEthic(R) three-dimensional models of the epidermis and in vivo clinical studies on Asian population confirm the strong inhibition of melanogenesis. Safety evaluation of these molecules, on the other hand, demonstrates good skin tolerance and absence of toxicity.

• Corrosion Science and Technology
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• v.16 no.5
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• pp.265-272
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• 2017

Inhibition of pitting corrosion of the copper sprinkler tubes by removing dissolved oxygen in water with sodium sulfite was studied on the wet sprinkler systems operated in 258 household sites. First, air in the sprinkler tubing was removed by vacuum pumping. The tube was then filled with sodium sulfite dissolved in water. Sodium sulfite was very effective in maintaining a very low dissolved oxygen concentration in water in the sprinkler tube for the observation period of six months. Water leakage from the copper sprinkler tube was reduced significantly by using sodium sulfite. Both pitting corrosion process and pitting corrosion inhibition mechanism were investigated by examining microscopical and structural aspects of corrosion pits formed in failed copper sprinkler tube. Pitting corrosion was caused by pressurized air as well as sediments such as sand particles in copper tubes through oxygen concentration cells. It was confirmed microscopically that growth of corrosion pits was stopped by reducing dissolved oxygen concentration to a very level by using sodium sulfite.

• Journal of Electrochemical Science and Technology
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• v.7 no.2
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• pp.153-160
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• 2016

The inhibition ability of N,N-bis(2,4-dihydroxyhydroxybenzaldehyde)-1,3-Propandiimine (DHBP) as a schiff base against the corrosion of API-5L-X65 steel in 1 M HCl solution was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy. Electrochemical impedance studies indicated that DHBP inhibited corrosion by blocking the active corrosion sites. The inhibition efficiency increased with increasing inhibitor concentrations. EIS data was analysed to equivalent circuit model and showed that the charge transfer resistance of steel increased with increasing inhibitor concentration whilst the double layer capacitance decreased. The adsorption of this compound obeyed the Langmuir adsorption isotherm. Gibbs free energy of adsorption was calculated and indicated that adsorption occurred through physical and spontaneous process. The corrosion inhibition mechanism was studied by potential of zero charge. Polarization studies indicated that DHBP retards both the cathodic and anodic reactions through adsorption on steel surface. Scanning electron microscopy was used to study the steel surface with and without inhibitor.

• Korean Journal of Acupuncture
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• v.21 no.2
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• pp.139-145
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• 2004

Objectives : Inhibition of phase I enzymes such as cytochrome P450 (CYP) 1A1 or 1A2 is considered a major mechanism of protection against initiation of carcinogenesis. The inhibition of toxic enzymes and CYP were studied with so many oriental herbral medicine. Recently, numerous polysaccharides and polysaccharide-protein complexes have been isolated from mushrooms and used as a source of therapeutic agents. The most promising biopharmacological activities of these polymers are their immunomodulation and anti cancer. But, in this study the inhibitory effect was on the aqua-acupuncture of Lentinus edodes. Materials : Lentinus edodes aqua-acupuncture solution (LEAS) was prepared and tested for the inhibition of cytochrome P450 (CYP) 1A1 and 1A2 activities. LEAS type I from fruit body of these mushrooms. Type II was extracted from cultured broth of Lentinus edodes mycelum. Results : LEAS type I and type II were significantly inhibited CYP 1A1 and 1A2 enzymes at concentration of 5.0 and 10.0 mg/ml. Conclusion : These results suggested that LEAS may act as block agent against carcinogenesis by inhibition of phase I enzymes.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.713-723
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• 2014

Biofouling in brackish water reverse osmosis (RO) membranes still needs extensive research to understand cause and mechanism and to obtain methods for reduction of its impact on RO applications. Natural compounds with biofilm formation inhibitory properties are being investigated. Two compounds, vanillin and Epigallocatechin gallate (EGCG), were selected due to their great potential on biofilm formation inhibition. Vanillin shows inhibition on quorum sensing mechanisms of biofilm formation. EGCG has potential to inactivate microbial activity. The two compounds were incorporated in typical polyamide reverse osmosis membranes and evaluated on flux behaviours and biofilm formation potential. The surface properties of membrane coated with vanillin were changed tremendously compared to those with EGCG. As a result, the flux was reduced substantially. The biofilm formation seems hindered with EGCG coated membranes compared to the virgin membranes. More research is needed to optimize coating methods applicable to RO membranes and to enhance biofouling reduction.

• The Korean Journal of Physiology
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• v.11 no.1
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• pp.1-9
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• 1977

Action of anthraquinone on the sodium plus potassium activated ATPase activity in the rabbit red cell membrane has been investigated and the experiments were also designed to determine the mechanism of action of anthraquinone on the ATPase activity. The following results were obtained 1. The activity of the NaK ATPase from red cell membrane is inhibited by anthraquinone and the concentration of anthraquinone for maximal inhibition is about 5mM. 2. The ratio of inhibition of NaK ATPase by anthraquinone, with a giving concentration of sodium in the medium, is increased by raising the potassium concentration. 3. The ratio of inhibition of NaK ATPase by anthraquinone, with a given concentration of potassium in the medium, is increased by raising the sodium concentration. 4. The action of anthraquinone on the NaK ATPase activity is inhibited by calcium ions and the ratio of inhibition is increased by small amounts of calcium but almost constant by larger amounts. 5. The inhibitory action of anthraquinone on the NaK ATPase activity was not related to the amino group of lysine, the hydroxyl group of threonine or the imidazole group of histidine. 6. The inhibitory action of anthraquinone on the ATPase activity is due to sulfhydryl group or the carboxyl group of the enzyme of NaK ATPase.

• Archives of Pharmacal Research
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• v.14 no.4
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• pp.330-335
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• 1991

The effects of physostigmine and neostigmine on the parathin induced toxicity were examined in adult female rats. Physostigmine $(100\;{\mu}g/kg,\;ip)$ or neostigmine $(200\;{\mu}g/kg,\;ip)$ inhibited acetylcholinesterase (AChE) and cholinesterase (ChE) activities in blood, brain and lung when the enzyme activity was measured 30 min after the treatment. At the doses of two carbamates equipotent on brain AChE, neostigmine showed greater inhibition on peripheral AChE/ChE. The enzyme activity returned to normal in 120 min following the carbamates except in the lung of rats treated with neostigmine. Carbamates administered 30 min prior to parathion (2 mg/kg) antagonized the inhibition of AChE/ChE by parathion when the enzyme activity was measured 2 hr following parathion. Neostigmine showed greater protective effect on peripheral AChE/ChE. The effect of either carbamate on AChE/ChE was not significant 2 hr beyond the parathion treatment. Carbamates decreased the mortality of rats challenged with a lethal dose of parathion (4 mg/kg, ip) either when treated alone or in combination with atropine (10 mg/kg, ip). Lethal action of paraoxon (1.5 mg/ks ip), the active metabolite of parathion was also decreased by the carbamate treatment indicating that the protection was not mediated by competitive inhibition of metabolic conversion of parathion to paraoxon. The results suggest that carbamylation of the active sites may not be the sole underlying mechanism of protection provided by the carbamates.

• YAKHAK HOEJI
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• v.43 no.5
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• pp.652-658
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• 1999

To reveal the inhibitory mechanism of NO-dependent vasorelaxation by quinone derivatives (OQ1 and OQ21), we have compared the generation of free radicals by oxidative stress and the formation of cellular adducts by arylation. First, we measured oxygen consumption by quinone derivatives as a marker of oxidative stress in order to investigate whether these quinone compounds could generate reactive oxygen species. Both OQ1 and OQ21 generated free radicals and OQ21 was more potent. These results suggested that free radicals be involved in the inhibition of vasorelaxation by quinones. Next, we measured the binding capacity of quinone derivatives with intracellular GSH and protein thiols (-SH) in order to investigate whether these quinones have arylation capacity. Compared to positive control groups (menadione), both OQ1 and OQ21 depleted intracellular GSH and protein thiols very slightly. These compounds have low toxicities in mammalian tissues. From these results, we concluded that the inhibition of vasorelaxation by quinone derivatives (OQ1, OQ21) may be cuased by generation of free radicals.

• Food Engineering Progress
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• v.15 no.4
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• pp.289-296
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• 2011

Twenty four fractions by solvent extraction and/or acid precipitation from fruit body and culture broth of Inonotus obliquus were prepared, and their inhibitory effect against acetylcholinesterase (AChE) was investigated. Among these fractions, acid (1 M HCl) precipitates from cell-free culture broth and fruit body exhibited the highest inhibitory effect on AChE in vitro. Acid precipitates inhibited AChE activity in a concentration-dependant manner and $IC_{50}$ values of both acid precipitates were 0.53 mg/mL. The inhibition pattern was general non-competitive inhibition. The energetic parameters were also determined by dual substrate/temperature design. Both acid precipitates increased the values of Ea, ${\Delta}H,/;{\Delta}G$ and ${\Delta}H^{\ast}$ decreasing the value of ${\Delta}S$ for AChE. The results implied that the acid precipitates from I. obliquus increased the thermodynamic barrier, leading to the breakdown of ES complex and the formation of products as inhibitory mechanism.