• Journal of Life Science
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• v.20 no.5
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• pp.736-744
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• 2010

The root of Playtcodon grandiflorum, called Platycodi radix, has been a favorite edible plant in Asia and contains a large amount of saponins. Melanoma cells (B16F10) were used to investigate the inhibitory effect of aged black Platycodi radix extract (ABPRE) on oxidative stress and matrix metalloproteinases (MMPs). Platycodon radix has been known to have a variety of medicinal effects such as prevention of gastric ulcers, antiallergenic activities, histamine release inhibition, and antioxidant effects. However, the mechanism of its action remains unclear in humans. ABPRE was prepared using ethanol extraction of aged black Platycodi radix. In an antioxidant effect study of ABPRE, it was observed that ABPRE specifically exhibited the scavenging activity of DPPH radical, but did not inhibit the production of malondialdehyde from lipid peroxidation. DNA oxidation was also blocked in the presence of ABPRE. In addition, ABPRE decreased the expression and activation of MMP-2 stimulated by phenazine methosulfate. Furthermore, ABPRE revealed the inhibitory effect on melanin production induced by L-dopa via antioxidant effect and the reduction of tyrosinase expression. Especially, the expression of antioxidant enzymes such as SOD-1 and SOD-2 regulated by Nrf2 was increased in the presence of ABPRE. Therefore, it appears that ABPRE may be a possible chemopreventive agent for the prevention of metastasis related to oxidative stress.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.917-923
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• 2009

The maize lipoxgyenase-1 is a non-traditional dual positional specific enzyme and the reaction proceeds via enzyme-initiated catalysis. Bioinformatic analysis indicated that the maize lipoxygenase-1 is structurally more similar to soybean LOX1 than pea LOXN2 in that it has an additional external loop (residues 318-351) in the carboxy-terminal catalytic domain. We analyzed the dependence of product distribution on concentration of linoleic acid and monitored the formation of hydroperoxyoctadecadienoic acid as a function of enzyme concentration. Product distribution was strongly influenced by substrate concentration, such that kinetically-controlled regioisomers were enriched and thermodynamically-controlled regioisomers were depleted at high substrate concentration. Kinetic studies indicated that the formation of hydroperoxyoctadecadienoic acid saturated rapidly in an enzyme concentration-dependent manner, which implied that reactivation by reoxidation of inactive Fe(II) failed to occur. Our results support the previously proposed enzyme-initiated catalytic mechanism of the maize lipoxgyenase-1 and reveals that a substrate molecule serves as a hydrogen atom donor in its enzyme-initiated catalysis.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.425-431
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• 1996

Human neutrophil elastases (HNElastase, EC 3.4.21.37), a causative factor of inflammatory diseases, are regulated by plasma proteinase inhibitors, alpha-proteinase inhibitor and ${\alpha}_2-macroglobulin$. Under certain pathological conditions, however, released enzymes or abnormal function of inhibitors may cause various inflammatory disease. NSAIDs have been clinically applied for treatment of inflammatory diseases. Inhibition of cyclooxygenase is a known mechanism of action of NSAIDs in the treatment of inflammatory disease. In in vitro experiments, HNElastase was inhibited by naproxen, phenylbutazone, and oxyphenbutazone, but ibuprofen, ketoprofen, aspirin, salicylic acid, and tolmetin did not inhibit elastase. HNElastase was also inhibited by chelating agents, EDTA & EGTA, and tetracyclines. Removal of divalent metal ions by EDTA caused inhibition of elastase, and reconstitution of the metal ions recovered the enzyme activity to a certain level. Frequencies and contours in the Raman spectra of various conditions of human neutrophil elastase undergo drastic changes upon partial removal and/or reconstitution of calcium and zinc ions. The metal ion content dependent activities and change of the contour of the Raman spectrogram suggest us that the mechanism of action of a chelator or chelator-like agents on neutrophil elastase may be related to the conformational change at/or near the active site, especially -C=O radical or -COOH radical.

• The Korean Journal of Pharmacology
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• v.27 no.2
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• pp.145-153
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• 1991

Human neutrophil cathepsin-G, which has been known as one of the active enzymes causing inflammatory diseases, was purified by two steps procedure involving one size exclusion (Ultorogel AcA54) and one ion exchange (CM-Sephadex) chromatography. Purified HNCGs were cross-reacted with Anti-HNCathepsin-G antibodies which were radised in rabbits and purified by cathepsin-G labeled Sepharose 4B affinity chromatography. HNCGs were effectively inhibited by NSAIDs including phenylbutazone, sulindac, oxyphenbutazone, salicylic acid and salicyluric acid. $IC_{50}_s$ of these drugs for inhibition of Cathepsin G were 0.3-0.8 mM. Other NSAIDs including aspirin showed little or no inhibition effect on the activity of Cathepsin G. These results strongly indicated that NSAIDs which showed inhibition effect on the activity of HNCGs possibly be at least a part of mechanism of action which might be related to direct inhibition of cathepsin G at the tissue destruction sites beside of their known mechanism of action as an anticyclo-oxygenase in treatment of inflammatory diseases. Lipid soluble component of Korean Red Ginseng which was known as an anti-inflammatory agent inhibited HNCGs strongly, but no other fractions did inhibited HNCGs. Antibiotics including novobiosin and rifamycin showed some inhibition effect on HNCGs, i. e.., $IC_{50}$ of these drugs were 2.6 mM and 1.5 mM respectively, and other antibiotics including penicillin G showed no or negligible inhibition effect on the activity of HNCGs. However. tetracyclines inhibited HNCGs very effectively at the concentration of therapeutic range. The inhibition effect of the activity of HNCGs by tetracycline are not related to the N-dimethyl radical on the 4 position of the tetracycline molecule. Furthermore, N-dedimethylated tetracyclines may have beneficial effect for long term treatment of chronic inflammatory diseases without developing any drug resistance to microorganisms.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4660-4670
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• 2022

Hydroxyurea (HU) is a novel salt-free reductant used potentially for the separation of U/Pu in the advanced PUREX process. In this work, the radiation stability of HU were systematically investigated in solution by examining the effects of the type of rays (α, β, and γ irradiations), the absorbed dose (10-50 kGy), and the HNO₃ concentration (0-3 mol L^-1). The influence degree on HU radiolysis rates followed the order of the absorbed dose > the ray type > the HNO₃ concentration, but the latter two had moderate effects on HU radiolysis products where NH₄⁺ and NO₂^- were found to be the most abundant ones, suggesting that the differences of α, β, and γ rays should be considered in the study of irradiation effects. The radiolysis mechanism was explored using density functional theory (DFT) calculations, and it proposed the dominant radiolysis paths of HU, indicating that the radiolysis of HU was mainly a free radical reaction among ·H, e_aq^-, H₂O, intermediates, and the radiolytic free radical fragments of HU. The results reported here provide valuable insights into the mechanistic understanding of HU radiolysis under α, β, and γ irradiations and reliable data support for the application of HU in the reprocessing of spent fuel.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.6
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• pp.1881-1891
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• 2004

Daejowhan-gamibang(DJG) is used to prevention and treatment of cerebrovascular disease, heart disease, dementia, hyperlipdemia circulatory disturbance. Korean traditional herbal prescriptions and herb medicines in neuronal cells, which have been used for the treatment of stroke and brain diseases in Korean traditional medicine were screened to study the antioxidant effects and its mechanism. Daejowhan-gamibang water extract(DJGWE) was tested on their antioxidant activity using radical scavenging effects against ABTS. It showed significant antioxidant capacities at 50㎍ concentration. The antioxidant activity of DJGWE was determined in the different concentration (10㎍, 50 ㎍, and 100㎍). At the same time, the antiperoxidation effects was determined. Lipid peroxidation in brain homogenates induced by NADPH and ADP-Fe/sup 2+/ was significantly inhibited by DJGWE in vitro. DJGWE showed a potent antioxidant and antiperoxidative activity, further investigation, in vitro and in vivo, will be needed for the confirm of possibility as an antioxidant therapeutic agents and their optimal treatment of brain diseases in human. In searching the mechanism of antioxidant effects of DJGWE, it showed the inhibition of activity of JNK, p38, ERK and caspase 3 induced by hypoxia. So, DJGWE should be surveyed for the use of the potential therapeutic prescription for stroke and brain degenerative diseases such as pakinson's disease, dementia.

• Herbal Formula Science
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• v.6 no.1
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• pp.215-226
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• 1998

Geagibokrounghwan (桂技茯笭湯) has long been used to cure human diseases such as vascular and blood disorders. However, it is still unkown on its action mechanism, physiolosical and biochemical meaning. Thus, many attempts were tried to show the scientific background covering the above mentioned mechanism. The effect of Geagibokrounghwan, which was known to date, as follow; effective circulation of body blood system, proliferation of leucocytes and antioxidative action. In this study, we have applied the Geagibokrounghwan administration and feed to mouse, to see effects on the expression of superoxide dismutase(SOD) mRNA as antioxidative agent and oxygen radical scavenger. Total RNAs includingmRNA have been isolated from liver and white blood cells after mice were fed with cholesterol in high dose. Also, in a separate group, the cholesterol-administrated mice were fed with Geagibokrounghwan to see the effects on SOD transcription. and then reverse transcriptase-polymerase chain reaction (RT-PCR) usion each primer set (SOD-F;GATGAAAGCGGTGT-3'; SOD-R; 5'-CCTGTGGAGTGATT-3') were performed to trace theamounts of mRNA. SOD mRNA was specifically expressed in Geagibokrounghwan-fed mice at 2 weeks after treatment, however, gradually reduced after 4 weeks. These results indicate that Geagibokrounghwan is highly applicable in treatment of the above mentioned human diseases.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.52-60
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• 2002

A two-dimensional direct numerical simulation is performed to investigate the flame structure of $CH_4/N_2-Air$ counterflow nonpremixed flame interacting with a single vortex. The detailed transport properties and a modified 16-step augmented reduced mechanism based on Miller and Bowman's detailed reaction mechanism are adopted in this calculation. To quantify the strain on flame induced by a vortex, a scalar dissipation rate (SDR) is introduced. Results show that the fuel and air-side vortex cause an unsteady extinction. In this case, the flame interacting with a vortex is extinguished at much larger SDR than steady flame. It is also found that air-side vortex extinguishes a flame more rapidly than fuel-side vortex. The unsteady effect induced by flame-vortex interaction does not lead to a transient OH overshoot of the maximum steady concentration observed in experiment, while $HO_2$ radical increases more than the maximum steady concentration with increasing SDR. In addition, it is seen that NO and $NO_2$ are not sensitive to the unsteady variation of SDR.

• Journal of Photoscience
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• v.3 no.2
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• pp.91-93
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• 1996

In connection with our interest on the photochemical properties of heteroaryl halides, which are currently the subject of heterocyclic ring formation and haloarene degradation, we have studied the photochemistry of the haloarene linked to N-heteroarene compounds. Imidazo[5,1-a]isoindole was synthesized from N-(ochlorobenzyl)imidazole or N-(o-bromobenzyl) imidazole in acidic aqueous solution or acetonitrile via the intramolgcular photocyclization (Table 1). This type of reaction provides the synthetic methods for 5- and 6-membered polyheteroatomic heterocyclic ring compounds. However, the reaction mechanism for the intramolecular photocyclization of haloarene tethered heteroarenes has not yet been established. Grimshaw et al. suggested a mechanism for homolyric carbonhalogen bond fission assisted by radical complexation to explain their results in the photocyclization of 5-(2-chlorophenyl)-1,3-diphenylpyrazole. They also reported the detection of acyclohexadienyl intermediate involved in the above reaction. Park et al. reported several transient 'intermediates involved in the laser flash photolysis of N-(o-halobenzyl) pyridinium and N-benzyl-2-halopyridinium salts. Thus we performed the laser flash photolysis study on the photocyclization reaction of N-(o-chlorobenzyl) imidazole to identify the intermediate species involved in the reaction. Here, we report on the preliminary results in the photocyclization reaction of N-(o-halobenzyl)imidazole through the detection of reaction intermediates.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.4
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• pp.614-619
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• 2011

Nelumbo nucifera(NN) is a oriental medicinal herb which has been used traditionally for the treatment of antidiarrhea, sedative action and various brain diseases including convulsion and epilepsy. In order to examine the mechanism of anticonvulsive effect, we treated the methanol extract of NN(100, 200 mg/kg, P.0) to the sleeping time and pentylenetetrazole(PTZ)-induced convulsive mice. The methanol extract of NN prolonged sleep time by pentobarbital. Methanol extracts of NN were not effected the concentration of GABA and GABA-T activity in the brain of PTZ-induced mice. Methanol extracts of NN significantly inhibited the convulsion state as well as the level of lipid peroxidation in the brain. The butanol and dichloromethane fraction of methanol extracts among the others effectively inhibited in vitro lipid peroxidation dose dependently($5.0{\times}10^{-6}\sim2.0{\times}10^{-5}\;g/ml$). These results suggest that the anticonvulsive effect of NN is possibly due to the antioxidative effects of the free radical formation at brain for the PTZ-induced convulsion if it were by due to generating system.