• Toxicological Research
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• v.11 no.2
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• pp.273-277
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• 1995

Several metabolic modulators on the generation of carbon monoxide (CO)from dichloromethane (DCM) was examined in adult female rats. It has been known that DCM is converted to CO by cytochrome P-450 or to carbon dioxide $(CO_2)$ by glutathione-dependent metabolic reaction. In rats treated with DCM (3 mmol/kg, ip) only, the carboxyhemoglobin (COHb) level reached a peak of approximately 10% 2 or 3 hr following the treatment. Disulfiram (300 mg/kg, ip) or allylsulfide (200 mg/kg, po), both known as a selective inhibitior for cytochrome P-450 2E1, blocked the increase in COHb concentratlons almost completely suggesting that the metabolic conversion of DCM to CO is mediated by the activity of this specific type of isozyme. YH439 (125 or 250 mg/kg, po), a potential hepatoprotective agent, decreased the COHb elevation as well indicating that this chemical is a potent inhibitor for 2E1. In rats treated with pyrazine (200 mg/kg, ip) 18 hr prior to DCM the peak COHb concentration was decreased by approximately 3 or 4%. However, pretreatment of rats with pyrazine either 24 or 48 hr before DCM increased the peak COHb concentration significantly compared to the rats treated with DCM only. The results in the present study strongly suggest that the generation of CO from DCM depends on the 2E1 activity and that the pharmacological and/or toxicological action of YH439 or pyrazine in animals or human is associated with its effect on this isozyme.

• Toxicological Research
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• v.11 no.2
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• pp.303-308
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• 1995

Nitric oxide, a physiological transmitter, is reported to mediate cellular injury in various tissues. Its reactivity to free radical is believed to be one of the reasons for its involvement in cytotoxicity. Menadione, a representative quinone, is cytotoxic to several cell systems including isolated hepatocyte, endothelial cell and red blood cells. Its toxic mechanism is related to oxidative stress, mediated by toxic free radicals. Our previous studies demonstrated that menadione induced cell lysis and increase of oxygen consumption in platelets. It has been reported that platelets have nitric oxide producing enzyme, nitric oxide synthase. Thus, we have investigated to manifest the role of nitric oxide.in menadione-induced cytotoxicity in rat platelets. Menadione induced cytotoxicity in platelets was unaffected by $N^G$-nitro-arginine methyl ester (L-NAME), selective and competitive inhibitor of nitric oxide synthase. We also invesitgated the role of extracellular nitric oxide in menadione-induced cytotoxicity of platelets by addition with sodium nitroprusside (SNP). SNP did not affect platelet cytotoxicity by menadione. These results suggested that nitric oxide which was generated endogeneously or exogeneously might have a negligible role in menadione-induced cytotoxicity in rat platelets.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.96-96
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• 2003

Previously, wogonin (5,7-dihydroxy-8-methoxyflavone) was found to suppress proinflammatory enzyme expression including cyclooxygenase-2 (COX-2), contributing to in vivo anti-inflammatory activity against skin inflammation. However, the detailed effect on each skin cell type has not been understood. Therefore, present investigation was carried out to find the effect of wogonin on inflammation-associated gene expression from skin fibroblasts in culture using reverse transcriptase-polymerase chain reaction. As a result, it was found that wogonin (10 - 100 ${\mu}$M) clearly down-regulated COX -2 expression from NIH/3T3 cells treated with 12-O-tetradecanoylphorbol 13-acetate, interleukin-1${\beta}$ or tumor necrosis factor-a. But, the expression levels of COX-1, interleukin-1${\beta}$ and fibronectin were not significantly affected. This finding was well correlated with significant reduction of prostaglandin E$_2$(PGE$_2$) production by wogonin. As a comparison, NS-398 (selective cyclooxygenase-2 inhibitor) did not suppress COX -2 expression and other gene levels, while PGE$_2$production was potently reduced at 0.1 - 10 ${\mu}$M. All these results suggest that COX -2 down-regulation of skin fibroblasts may be, at least in part, one of anti-inflammatory mechanisms of wogonin against skin inflammation.

• Archives of Pharmacal Research
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• v.29 no.12
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• pp.1119-1124
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• 2006

The methanol extract from the aerial parts of Dictamnus albus was active in inhibiting monoamine oxidase (MAO) from the mouse brain. Activity-guided fractionation led to the isolation of four known coumarins, 7-(6'R-hydroxy-3', 7'-dimethyl-2'E, 7'-octadienyloxy) coumarin (1), auraptene (2), umbelliferone (3), and xanthotoxin (4), as active compounds along with an inactive alkaloid, skimmianine (5). Compounds 1 and 2 inhibited MAO activity in a concentration-dependent manner with $IC_{50}$ values of 0.7 and $1.7\;{\mu}M$, respectively. Compounds 1 and 2 showed a slight and potently selective inhibitory effect against MAO-B ($IC_{50}\;0.5\;and\;0.6\;{\mu}M,\;respectively$) compared to MAO-A ($IC_{50}\;1.3\;and\;34.6\;{\mu}M,\;respectively$). According to kinetic analyses derived by Lineweaver-Burk reciprocal plots, compounds 1 and 2 exhibited a competitive inhibition to MAO-B.

• Fisheries and Aquatic Sciences
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• v.19 no.9
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• pp.35.1-35.6
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• 2016

Gliotoxin has been recognized as an immunosuppressive agent for a long time. Recently, it was reported to have antitumor properties. However, the mechanisms by which it inhibits tumors remain unclear. Here, we showed that gliotoxin isolated from the marine fungus Aspergillus fumigatus inhibited proliferation and induced apoptosis in HT1080 human fibrosarcoma cells. Gliotoxin repressed phosphorylation-dependent degradation of $I{\kappa}B-{\alpha}$, an antagonist of nuclear factor kappa B ($NF-{\kappa}B$), which is a known tumor-promoting factor. This coincided with a decrease in nuclear import of $NF-{\kappa}B$, suggesting its signaling activity was impaired. Moreover, gliotoxin increased intracellular reactive oxygen species (ROS). Since ROS have been known to inhibit $NF-{\kappa}B$, this may also contribute to gliotoxin's antitumorigenic effects. These results suggest that gliotoxin suppressed the activation of $NF-{\kappa}B$ by inhibiting phosphorylation and degradation of $I{\kappa}B-{\alpha}$ and by increasing ROS, which resulted in apoptosis of HT1080 cells. Cumulatively, gliotoxin is a promising candidate antagonist of $NF-{\kappa}B$, and it should be investigated for its possible use as a selective inhibitor of human fibrosarcoma cells.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.5
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• pp.299-304
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• 2010

Losartan is a selective angiotensin II (Ang II) type 1 ($AT_1$) receptor antagonist which inhibits vascular smooth muscle cells (VSMCs) contraction and proliferation. We hypothesized that losartan may prevent cell proliferation by activating AMP-activated protein kinase (AMPK) in VSMCs. VSMCs were treated with various concentrations of losartan. AMPK activation was measured by Western blot analysis and cell proliferation was measured by MTT assay and flowcytometry. Losartan dose- and time-dependently increased the phosphorylation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC) in VSMCs. Losartan also significantly decreased the Ang II- or 15% FBS-induced VSMC proliferation by inhibiting the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. Compound C, a specific inhibitor of AMPK, or AMPK siRNA blocked the losartan-induced inhibition of cell proliferation and the $G_0/G_1$ cell cycle arrest. These data suggest that losartan-induced AMPK activation might attenuate Ang II-induced VSMC proliferation through the inhibition of cell cycle progression.

• Natural Product Sciences
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• v.18 no.2
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• pp.102-105
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• 2012

Marine organism extracts were prepared from 26 species of Korean indigenous marine organisms, including 25 species belonging in class Anthozoa of phylum Cnidaria and a species belonging to subphylum Urochordata of phylum Chordata, and screened their inhibitory effects against ${\mu}$-calpain. As a result, the thirteen extracts were found to be active in the criteria of $IC_{50}$ < 100 ${\mu}g/ml$. Among them, the MeOH extracts of Plexauroides praelonga and Alveopora japonica showed remarkable ${\mu}$-calpain inhibitory activity with $IC_{50}$ values of $4.62{\pm}0.22$ and $4.82{\pm}0.07{\mu}g/ml$, respectively. In addition, chemical investigation of A. japonica led to the isolation of an active compound, hexadecyl tetradecanoate, as a selective cathepsin B inhibitor ($IC_{50}=9.05{\pm}2.45{\mu}M$). This compound was isolated as constituent of A. japonica for the first time in the present study.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.66-66
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• 1995

Mutated forms of the ras oncogenes are associated with about 30% of human tumors. The ras genes encode 21KDa proteins, called p21 or Ras, that are associated with the plasma membrane. FPTase is a dimeric enzyme that catalyses the transfer of the farnesyl group from farnesyl pyrophosphate onto cysteine 186 at the C-terminus of the Ras protein. This is mandatory process for triggering ras oncogene toward tumor formation. Therefore, selective inhibitors of FPTase have the potential to be used as antitumorgenic agents.

• Tuberculosis and Respiratory Diseases
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• v.71 no.3
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• pp.210-215
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• 2011

Imatinib mesylate, a selective inhibitor of BCR-ABL kinase activity, has demonstrated significant clinical efficacy in the treatment of chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GISTs). It has become the standard of treatment for these diseases. Although the toxicity profile of imatinib is superior to that of interferon or other cytotoxic agents, some adverse events including edema, gastrointestinal toxicities and hematologic toxicities are commonly observed in the patients treated by imatinib. We present two cases of imatinib induced interstitial pneumonitis during the treatment of a chronic phase of CML.

• Molecules and Cells
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• v.39 no.3
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• pp.186-194
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• 2016

Epidemiological evidence suggests that bone is especially sensitive to oxidative stress, causing bone loss in the elderly. Previous studies indicated that human amnion-derived mesenchymal stem cells (HAMSCs), obtained from human amniotic membranes, exerted osteoprotective effects in vivo. However, the potential of HAMSCs as seed cells against oxidative stress-mediated dysfunction is unknown. In this study, we systemically investigated their antioxidative and osteogenic effects in vitro. Here, we demonstrated that HAMSCs significantly promoted the proliferation and osteoblastic differentiation of $H_2O_2$-induced human bone marrow mesenchymal stem cells (HBMSCs), and down-regulated the reactive oxygen species (ROS) level. Further, our results suggest that activation of the ERK1/2 MAPK signal transduction pathway is essential for both HAMSCs-mediated osteogenic and protective effects against oxidative stress-induced dysfunction in HBMSCs. U0126, a highly selective inhibitor of extracellular ERK1/2 MAPK signaling, significantly suppressed the antioxidative and osteogenic effects in HAMSCs. In conclusion, by modulating HBMSCs, HAMSCs show a strong potential in treating oxidative stress- mediated bone deficiency.