• Natural Product Sciences
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• v.10 no.2
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• pp.80-84
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• 2004

Rosmarinic acid and its methyl ester, isolated from the ethyl acetate soluble fraction of the methanolic extract of Salvia miltiorrhiza Bunge (Labiatae), were found to inhibit the oxidation of L-tyrosine catalyzed by mushroom tyrosinase with the $IC_{50}$ values of 16.8 and $21.5\;{\mu}M$, respectively. It was comparable with kojic acid, a well-known tyrosinase inhibitor, with an $IC_{50}$ of $22.4\;{\mu}M$. The inhibitory kinetics analyzed by the Lineweaver-Burk plots, were found rosmarinic acid and its methyl ester to be competitive inhibitors with $K_i\;of\;2.4{\times}10^{-5}\;and\;1.5{\times}10^{-5}\;M$, respectively.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.469-481
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• 1993

The purpose of this study was to achieve the reduction of the galvanic current between the dental amalgam alloy and gold alloy. In order to measure the galvanic current between these two metals a prep in the size of $4{\times}13mm$ which was filled with amalgam and another prep of $4{\times}2mm$ was filled with gold alloy was made in the acrylic resin. These two preps were then connected to a 2mm diameter copper wire. Using an ammeter to measure the galvanic current, six different kinds of amalgam and gold alloy were immersed in saline solution with approximately 10mm distance between the two alloys. Chemical agents that are thought to reduce the galvanic current such as hydrazine. silver nitrate, potassium chromate, and bonding agents such as Scotch bond 2(3M) and All bond 2(Bisco) were applied to the alloy surface. Cathodic inhibitor such as hydrazine was applied to gold alloy where as anodic inhibitor such as silver nitrate and potassium chromate were applied to amalgam. Both bonding agents, Scotch bond 2(3M) and All bond 2 (Bisco), were applied to amalgam. The following results were obtained when the currency on the coated alloy surface was compared to the uncoated surface. 1. The galvanic currency went down as the time elapsed and after 30 minutes no change was detected. 2. Initial currency was higher in low copper amalgam compared to high copper amalgam. Intitial currency was the highest in low copper lathe-cut amalgam. 3. Group of gold coated with hydrazine had the most reduction in galvanic currency. 4. Group of amalgam coated with silver nitrate or potassium chromate also showed significant reduction in galvanic currency. 5. The bonding agents also helped reduce galvanic currency. 6. Of all the agents used to reduce galvanic currency, silver nitrate showed the best result.

• BMB Reports
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• v.42 no.9
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• pp.580-585
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• 2009

Dimethyl sulfoxide (DMSO) is widely used in chemistry and biology as a solvent and as a cryoprotectant. It is also used as a pharmaceutical agent for the treatment of interstitial cystitis and rheumatoid arthritis. Previous reports described DMSO as being reduced by methionine-S-sulfoxide reductase (MsrA). However, little is known about the DMSO reduction capability of methionine-R-sulfoxide reductase (MsrB) or its effect on the catalysis of methionine sulfoxide reduction. We show that mammalian MsrB2 and MsrB3 were unable to reduce DMSO. This compound inhibited MsrB2 activity but did not inhibit MsrB3 activity. We further determined that DMSO functions as an inhibitor of MsrA and MsrB2 in the reduction of methionine sulfoxides via different inhibition mechanisms. DMSO competitively inhibited MsrA activity but acted as a non-competitive inhibitor of MsrB2 activity. Our study also demonstrated that DMSO inhibits in vivo methionine sulfoxide reduction in yeast and mammalian cells.

• Toxicological Research
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• v.14 no.2
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• pp.157-161
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• 1998

The mechanism of active aldehyde-induced liver disease and the enzymatic basis of detoxification were investigated using normal rat liver cell, Ac2F. Aliphatic alcohols including l-decyl alcohol, l-nonanol, l-heptanol, l-hexanol, l-propanol and allyl alcohol exerted a dose- and time-de-pendent toxicity to Ac2F cells. The extent of their toxicities in buthionine sulfoximine (inhibitor of glutathione synthesis) pretreated cells was greater than in pargyline (inhibitor of aldehyde dehydrogenase, ALDH). On the other hand, the toxicity of these alcohols were not affected by 4-methylpyrazole (inhibitor of alcohol dehydrogenase, ADH). These results suggest that the contents of glutathione (GSH) seems to be very important in protecting the cells from toxicants such as aliphatic alcohols.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.9-13
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• 2001

Genistein, a natural isoflavonoid phytoestrogen, is a strong inhibitor of protein tyrosine kinase and DNA topoisomerase II activities. Genistein has been shown to have anticancer proliferation, differentiation and chemopreventive effects. In the present study, we have addressed the mechanism of action by which genistein suppressed the proliferation of p53-null human prostate carcinoma cells.(omitted)

• Journal of Life Science
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• v.19 no.6
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• pp.818-824
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• 2009

The mechanisms responsible for ischemia/reperfusion (I/R) injury have direct or indirect relevance to clinical lung injury after severe shock, cardiopulmonary bypass, and transplantation. This study investigated the effects of aspirin on intestinal I/R-induced acute lung injury (ALI) in rats. Lipopolysaccharide (LPS) induced cyclooxygenase-2 (COX-2) expression in A549 and RAW264.7 cells. RAW264.7 macrophages had shown greater expression of COX-2 than A549 cells. In addition, the NADPH oxidase inhibitor apocynin and p38 MAPK inhibitor SB203580 attenuated LPS-stimulated COX-2 expression. To induce ALI, intestinal ischemia was performed for 60 min prior to the 4 hr reperfusion by clamping the superior mesenteric artery in Sprague-Dawley rats. In order to test and compare the effect of non-specific COX inhibitor aspirin with the effect of mepacrine, a well known phospholipase$A_{2}$ inhibitor, rats were divided into 4 groups: Sham, I/R, Mepa+I/R (mepacrine, 60 mg/kg, i.p.), ASA+I/R (aspirin, 10 mg/kg, i.p.). In the present investigation, myeloperoxidase activities in the lung and intestinal tissues were increased by I/R. These changes were reduced by single pretreatment of mepacrine (60 mg/kg, i.p.) or aspirin (10 mg/kg, i.p.) 30 min before I/R. Structural studies demonstrated that the tissue injuries in the lung and intestine after I/R were also attenuated by the pretreatment of mepacrine or aspirin. These results suggest that I/R-induced ALI is mediated, in part, by the activation of COX. In addition, pretreatment of aspirin might be helpful for the prevention of ALI in ARDS-prone patients. In addition, the p38 MAPK inhibitor and apocynin also might be helpful to ALI through the inhibition of COX-2 expression.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.2
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• pp.139-147
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• 2013

Lysolipids such as LPA, S1P and SPC have diverse biological activities including cell proliferation, differentiation, and migration. We investigated signaling pathways of LPA-induced contraction in feline esophageal smooth muscle cells. We used freshly isolated smooth muscle cells and permeabilized cells from cat esophagus to measure the length of cells. Maximal contraction occurred at $10^{-6}M$ and the response peaked at 30s. To identify LPA receptor subtypes in cells, western blot analysis was performed with antibodies to LPA receptor subtypes. LPA1 and LPA3 receptor were detected at 50 kDa and 44 kDa. LPA-induced contraction was almost completely blocked by LPA receptor (1/3) antagonist KI16425. Pertussis toxin (PTX) inhibited the contraction induced by LPA, suggesting that the contraction is mediated by a PTX-sensitive G protein. Phospholipase C (PLC) inhibitors U73122 and neomycin, and protein kinase C (PKC) inhibitor GF109203X also reduced the contraction. The PKC-mediated contraction may be isozyme-specific since only $PKC{\varepsilon}$ antibody inhibited the contraction. MEK inhibitor PD98059 and JNK inhibitor SP600125 blocked the contraction. However, there is no synergistic effect of PKC and MAPK on the LPA-induced contraction. In addition, RhoA inhibitor C3 exoenzyme and ROCK inhibitor Y27632 significantly, but not completely, reduced the contraction. The present study demonstrated that LPA-induced contraction seems to be mediated by LPA receptors (1/3), coupled to PTX-sensitive G protein, resulting in activation of PLC, PKC-${\varepsilon}$ pathway, which subsequently mediates activation of ERK and JNK. The data also suggest that RhoA/ROCK are involved in the LPA-induced contraction.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.325.3-326
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• 2002

An imbalance between matrix metalloproteinase (MMP)-2 and its endogenous inhibitor. tissue inhibitor of metalloproteinase (TIMP)-2 causes the degradation of the extracellular matrix associated with pathological events including invasion. metastasis and angiogenesis. Since TIMPs are secreted molecules. they have the potential to be used for gene therapy of certain tumors. (omitted)

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.6-11
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• 1999

Dialkylamine (di-)nitrobenzoates as vapor corrosion inhibitor were synthesized with dialkylamines and (di-)nitrobenzoic acids. The compounds were analyzed by elemental analyzer, FT-IR and $^1H$-NMR spectrophotometer. Corrosion inhibition of synthetic compounds and additives [$(NH_4)_2CO_3$, $NaHCO_3$] against ferrous and non-ferrous metal was investigated by potentiostatic method [1% (w/v) corrosion inhibitor in 1M $Na_2SO_4$ aqueous solution] respectively. For corrosion inhibition of ferrous metal, dialkylamine 4-nitrobenzoates were better inhibitor than dialkylamine 3, 5-dinitrobenzoates, the passivating current density ($i_p$) of dialkylamine 4-nitrobenzoate was shown $4.78mA/cm^2$. While, for non-ferrous metal, dialkylamine 3, 5-dinitrobenzoates were better, those of dipropylamine 3, 5-dinitrobenzoate and hexamethyleneimine 3, 5-dinitrobenzoate were shown 36 and $37mA/cm^2$. Additive effect of $(NH_4)_2CO_3$ and $NaHCO_3$ for corrosion inhibition of ferrous metal was excellent but that of non-ferrous metal was not. Optimum ratios of diethylamine 4-nitrobenzoate with $(NH_4)_2CO_3$ and $NaHCO_3$ were 4 : 6 and 5 : 5 (V/V), and passivating current densities ($i_p$) of the mixtures were shown 0.26 and $0.85mA/cm^2$, respectively.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.5
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• pp.243-249
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• 2006

The effect of genistein, widely used as a specific tyrosine kinase inhibitor, on rat brain Kv1.5 channels which were stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Genistein inhibited Kv1.5 currents at +50 mV in a concentration-dependent manner, with an $IC_{50}$ of $54.7{\pm}8.2\;{\mu}M$ and a Hill coefficient of $1.1{\pm}0.2$. Pretreatment of Kv1.5 with protein tyrosine kinase inhibitors ($10\;{\mu}M$ lavendustin A and $100\;{\mu}M$ AG1296) and a tyrosine phosphatase inhibitor ($500\;{\mu}M$ sodium orthovanadate) did not block the inhibitory effect of genistein. The inhibition of Kv1.5 by genistein showed voltage-independence over the full activation voltage range positive to 0 mV. The activation (at +50 mV) kinetics was significantly delayed by genistein: time constant for an activation of $1.4{\pm}0.2$ msec under control conditions and $10.0{\pm}1.5$ msec in the presence of $60\;{\mu}M$ genistein. Genistein also slowed the deactivation of the tail currents, resulting in a crossover phenomenon: a time constant of $11.4{\pm}1.3$ msec and $40.0{\pm}4.2$ msec under control conditions and in the presence of $60\;{\mu}M$ genistein, respectively. Inhibition was reversed by the application of repetitive depolarizing pulses, especially during the early part of the activating pulse. These results suggest that genistein directly inhibits Kv1.5 channels, independent of phosphotyrosine-signaling pathway.