• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.103-106
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• 2002

A new reaction mechanism is proposed for the reaction of thianthrene cation radical perchlorate $(Th^{+{\cdot}}CIO_4^-}$ and tert-butyl peroxide in acetonitrile at room temperature on the basis of experimental and theoretical results. Rapid C-O bond rupture instead of O-O bond cleavage was observed by a good peroxy radical trapping agent, thianthrene cation radical. Products were N-tert-butyl acetamide, thianthrene 5-oxide (ThO), thianthrene 5,5-dioxide $(SSO_2)$, and thianthrene (Th). Thianthrene 5,10-dioxide (SOSO) was not obtained. A comparative computational study of the cation radical of tert-butyl peroxide is made by using B3LYP and CBS-4. The computational results are helpful to explain the reaction mechanism.

• Journal of Acupuncture Research
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• v.17 no.3
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• pp.176-187
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• 2000

Objectives : This study was purposed to investigate the antioxidative effects of Paeoniae radix aqua-acupuncture solution(PR) on culture liver cell system, lipid peroxidation and antioxidative enzyme activities in tert-butyl hydroperoxide(t-BHP) treatmented conditions. Methods : Cultured normal rat liver cell(Ac2F) were prepared and incubated with or without PR(at 2% volume in culture medium). After 16~18hr, cells placed in DMEM medium without serum, and then incubated with 1mM t-BHP for 2hr. Viable cells were detected by MTT assay, and the levels of lipid peroxide(LPO) were measured by TBA method. And catalase activity was measured as the decrease in hydrogen peroxide absorbance at 240nm on spectrophotometer using 30mM hydrogen peroxide. Superoxide dismutase(SOD) were assayed by recording the inhibition of nitro blue tetrazolium reduction with xanthine and xanthine oxidase. Glutathione peroxidase(GPX) activity was determined by the modified coupled assay developed by Paglia and Lawrence. The reaction was started by addition of 2.2mM hydrogen peroxide as substrate. The change in absorbance at 340nm was measured for 1min on spectrophotometer. Glutathione-S-transferase(GST) activity was assayed with CDNB as substrate and enzyme activity of GST towards the glutathione conjugation of CDNB. Results : Cell killing was significantly enhanced by addition of t-BHP compared to those of untreated group. PR pretreated cell resisted the toxic effects of t-BHP. LPO levels of t-BHP treatment group were significantly higher than other groups. This increased level was significandy reduced by PR pretreatment. The t-BHP treatment resulted in a decrease of catalase, GPX and GST activities. By contrast, PR pretreatment markedly increased compare to those of untreated groups. Conclusions : T-BHP which can produce intracellular free radical was used for inducer of the peroxidation of cellular lipids. PR protected the cell death induced by t-BHP and significantly increased cell viabiliry in the normal rat liver cell, and showed effective inhibition of lipid peroxidation, and elevations of catalase, GPX and GST activities. These results suggested that PR might play a protective role in lipid peroxidation by free radicals.

• Proceedings of the Korean Biophysical Society Conference
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• 1998.06a
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• pp.33-33
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• 1998

Oxidation and reduction of amino acid residues in proteins affect their functional properties. Especially, redox modulation of ion channel activities has been reported in number of ion channel proteins. In this study, we investigated the effects of tertiary-butyl hydrogen peroxide (tBHP) on the large-conductance Ca$\^$2＋/ -activated K$\^$+/(Maxi-K) channel of rat brain using lipid bilayer reconstitution technique.(omitted)

• Journal of the Korean Chemical Society
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• v.19 no.5
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• pp.367-374
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• 1975

Glycine residue in N-X-glycylphenylalanine methyl ester(X = trifluoroacetyl or acetyl) was converted into aspartic acid derivative by a photoalkylation reaction. The reaction was induced with 350 nm lamp using a combination of diacetyl/di-t-butyl peroxide (DBP) as the photoinitiator, and acetic anhydride as the alkylating agent. In the thermal reaction with DBP and acetic anhydride, the same alkylation reaction of the dipeptide was observed. From this thermal alkylation reaction the photoalkylation reaction is also thought to undergo via free radical mechanism.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.380-384
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• 1987

Reactions of methylenethioxanthene (3) with n-propanethiol in the presence of di-t-butyl peroxide(DTBP) afforded preferentially propyl 9-thioxanthenylidenemethyl sulfide(8) rather than propyl 9-thioxanthenylmethyl sulfide(9) regardless of the concentration of n-propanethiol. On the other hand reactions of 3 with a low concentration of n-propanethiol in the presence of dibenzoyl peroxide(DBPO) gave 8, 1,2-bisthioxanthenylidene ethane(11), and thioxanthenylidenemethyl benzoate(12) but only 8 was formed at high concentration of the thiol. The formations of these products were rationallized by an electron transfer mechanism.

• Herbal Formula Science
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• v.10 no.2
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• pp.127-141
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• 2002

Objectives: Haeganjeon(HGJ) has been used for the treatment of liver disease in traditional medicine. The present study was carried out to evaluate the antioxidant and protective effects of HGJ extract on oxidative damage of hepatocytes by tert-butyl hydroperoxide(t-BHP). Methods: In the linoleic acid water-alcohol system, the levels of lipid peroxide(LPO) were determined by TBA method. The scavenging effect of HGJ on ${\alpha},{\alpha}-diphenyl-{\beta}-picrylhydrazyl$(DPPH) radical was determined according to the method of Hatano. In the Fenton system(ferrous ion reaction with hydrogen peroxide), the levels of hydroxyl radical induced LPO in rat liver homogenate were determined according to the method of TBA. Inhibitory effect of HGJ on superoxide generation was measured by xanthine-xanthine oxidase system. In order to evaluate antioxidative activity of HGJ in the liver cell, cultured normal rat liver cells(Ac2F) were prepared and incubated with or without HGJ. After 18hr, cells placed in DMEM medium without serum, and then incubated with 1mM tert-butyl hydroperoxide(t-BHP) for 2hrs. Viable cells were detected by MTT assay. Conclusions: In the linoleic acid autoxidation system, HGJ extract significantly inhibited the time course of the lipid peroxidation. These effects were similar to those of BHA HGJ extracts showed about 70% scavenging effect on DPPH radical. And HGJ extract inhibited the lipid peroxide formation in rat liver homogenate induced by hydroxyl radical derived from Fenton system. In addition, HGJ extract protected the cell death induced by t-BHP and significantly increased cell viability in the normal rat liver cell. These result indicated that HGJ extract might playa protective role against oxidative hepatic cell injury by means of free radical scavenger.

• Herbal Formula Science
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• v.26 no.4
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• pp.329-340
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• 2018

Objectives : In Traditional Korean medicine, Daucus carota L. has been used for treating dyspepsia, diarrhea, dysentery and cough. Recent pharmacognosic evidence showed D. carota has anti-oxidant, anti-cancer, anti-fungal, and hypotensive effects. Present study investigated hepato-protective effect of D. carota ethanol extract (DCE) against oxidative stress in HepG2 cells. Methods : After HepG2 cells were pretreated with different concentrations of DCE, the cells were exposed to tert-butyl hydroperoxide (tBHP) for inducing oxidative stress. Cell viability, hydrogen peroxide production, glutathione concentration, and mitochondrial membrane potentials were measured to explore hepato-protective effect of DCE. Phosphorylation of AMP-activated protein kinase (AMPK) and effect of compound C on cell viability were determined to investigate the role of AMPK on DCE-mediated cytoprotection. Results : DCE significantly decreased the tBHP-mediated cytotoxicity in a concentration dependent manner and reduced the changes on apoptosis-related proteins by tBHP in HepG2 cells. In addition, DCE significantly prevented hydrogen peroxide production, glutathione depletion, and mitochondrial membrane impairment induced by tBHP. Treatment with DCE increased phosphorylation of AMPK, and the DCE-mediated cytoprotection was abolished by pretreatment with compound C. Conclusions : These results demonstrate that DCE can protect hepatocytes from oxidative stress through activation of AMPK.

• Herbal Formula Science
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• v.8 no.1
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• pp.241-255
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• 2000

Sihosamultang(SST) has been used for the treatment of puerperal fever, liver disease in traditional medicine. The present study was carried out to evaluate the antioxidant effects of SST extract in vitro. The inhibitory effect of SST extract on lipid peroxidant was examined in the linoleic acid autoxidation system. In this test, SST extract significantly inhibited the time course of the lipid peroxidation. And SST extract showed about 73% scavenging effect on DPPH radical. And this extract inhibited not only the lipid peroxide formation induced by hydroxyl radical derived from $ H_{2}O_{2}-Fe^{2+}$ in the rat liver homogenate, but also the superoxide generation from xanthine-xanthine oxidase system in a dose-dependent manner. In addition, SST extract protected the hepatic cell death induced by tert-butyl hydroperoxide. These data indicated that SST might play a protective role against oxidative injury by free radicals.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.121-125
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• 2003

Enzymatic polymerization of cardol derived from cashew nut shell liquid have been examined. t-Butyl alcohol aqueous systems showed high yield of polycardol when SBP was as biocatalyst. Compared other solvents, peroxidase actiyity was maintained stable, which was seemed major cause. Solvent aqueous system and concentration of hydrogen peroxide were found to have an influence on the yield and molecular weight distribution of polycardol under the reaction of enzymatic polymerization using peroxidase. The polymer was subjected to the hardening by methyl ethyl ketone peroxide and cobalt naphthenate catalyst, giving a crosslinked tough film. Polycardol was cured rapidly and the hardness increased with time. Finally, the pencil scratch hardness reached to 7H, which is enough hard for industrial uses.

• Bulletin of the Korean Chemical Society
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• v.11 no.4
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• pp.343-347
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• 1990

A thermal decomposition of the tert-butoxy radical has been studied in the gas phase over the pressure range of 1-200 torr at $413_{\circ}K$ using di-tert-butyl peroxide + trimethylsilane mixtures. The relative rate constants were obtained by studying the competitive reactions between tert-butoxy radical decomposition 4(t-BuO·→ CH_3COCH_3 + CH_3·)$ and hydrogen abstraction reaction from trimethylsilane $(t-BuO·+ HSi(CH_3)_3 → t-BuOH + Si(CH_3)_3)·).$ The conventional RRKM calculations were carried out to compare the observed fall-off behavior of the decomposition rate constant $({\kappa}_d)$ with the theoretical predictions using reasonable values of input parameters. In all cases the calculated half-rate pressure $(P_{1/2})$ were significantly higher than those observed. The failure of RRKM to reproduce the fall-off behavior led us to suggest that not all of vibrational modes contribute to excitation (leading to decomposition) on the same time scale.