• YAKHAK HOEJI
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• v.45 no.4
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• pp.387-396
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• 2001

The effects of ascorbic acid, thiols such as cysteine, n-acetyl-ι-cyteine, glutathione, thiourea, 2-mercaptoethanol and dithiotreithol and organic acids such as magic acid, citric acid, glycolic acid, taurine and kojic acid on polyphenol oxidate (PPO) activity were studied in order to establish if it reacts with oxidized product and/or directly inhibits the enzyme. To investigate the mechanism, the quantification of t-butylcatechol and 4-methylcatechol (phenolic compounds) as substates, their oxidized product and sulphydryl colorless additional compounds were determined by high performance liquid chromatograph (HPLC) method. Chromatographic results indicate that ascorbic acid, organic acids and lower level of cysteine reduced oxidized product of substrates back to their respective positions uf ο-diphenols. On the other hand, other thiols and high level of cysteine reacted with oxidative product of ο-diphenols and then produced sulphydryl colorless compounds. Cysteine apperars to have two types of mechanism of actions in the formation of oxidative products of substrates depending on its concentration; ascorbic acid-type and other thiols-types. The effect of ascorbic acid with thiols on polyphenol oxidase was determined by same method. Chromatographic results indicate that ascorbic acid was more reactive with oxidized product of substrates than thiols.

• Journal of Life Science
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• v.11 no.2
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• pp.99-102
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• 2001

Mouse malignant T-lymphoma CS21 cells can grow when cocultured with CAl2 lymph node stromal cells, but they undergo apoptotic cell death with DNA fragmentation when separated from CA12 stromal cells. In the course of examining the effects of the soluble factor (s) secreted by CAl2 stromal cells on CS2l cell growth, we found that thiols including cysteine promoted CS2l cell growth. P388 cell growth was also promoted by various thiols. These results suggest that thiols including cysteine participate in CA12 and P388 cell growth.

• Toxicological Research
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• v.13 no.3
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• pp.223-228
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• 1997

Quinones have been reported to undergo nonenzymatic reaction with thiols to generate reactive oxygens. It is therefore possible that the nonenzymatic reaction of quinones with thiols in plasma could lead to potentJared cellular toxicity or disease. When 1 mM menadione was added in plasma under pH 11.2, 7.4 and 5.0, the increase in oxygen consumption rate was the order of pH 11.2 > pH 7.4 > pH 5.0. In addition, oxygen consumption rates under plasma anticoagulated with trisodium citrate solution (pH 7.85) was significantly higher than those with acid-citrate-dextrose solution (pH 6.87). SOD and catalase reduced the rate of oxygen consumption induced by menadione in plasma. Taken together, these results suggest that the menadione-induced increased oxygen consumption was due to nonenzymatic reaction of menadione with thiols in the plasma. The presence of plasma has an additive effect on the increased oxygen consumption rates induced by the menadione treatments on our model tissue, platelets, as compared between washed platelet (WP) and platelet rich plasma (PRP). Cytotoxicity, as determined by LDH release, are well correlated with the oxygen consumption rates observed in each system and strongly suggest that menadione-induced cytotoxicity can be increased with the presence of blood plasma.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.383-386
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• 2012

A convenient synthesis of sulfonamides from thiols and disulfides is described. In situ preparation of sulfonyl chlorides from thiols is accomplished by oxidation with 1,3-dichloro-5,5-dimethylhydantoin (DCH) under Nbenzyl-trimethylammonium chloride and water. The sulfonyl chlorides are then further allowed to react with excess amine in the same reaction vessel.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1071-1076
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• 2009

N,N,N′,N′-tetramethylethylenediamine (TMEDA) acts as a simple, mild and efficient catalyst for the acylation of alcohols, phenols and thiols at room temperature under solvent-free condition. Acylation reaction with acetic anhydride and benzoic anhydride proceeds with good to excellent yield in the presence of TMEDA as the catalyst.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.609-613
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• 1995

The reaction of chloro(methylthio and arylthio)methanephosphonate (1) and Pummerer-type reaction of sulfinylmethanephosphonate (2) with nucleophiles such as aromatic compounds and thiols were examined. The direct chlorination of (methylthio and arylthio)methanephosphonate with N-chlorosuccinimide (NCS) led to the formation of monochlorinated phosphonates (1) in good yield. The reaction of 1 with aromatic compounds and thiols in the presence of stannic chloride afforded a variety of aryl(methylthio)methanephosphonates (3) and thioacetals of formylphosphonates (4), respectively. Phosphonates 3 and 4 were also obtained from the reaction of Pummerer intermediate, generated from sulfinylmethanephosphonate (2), with aromatic compounds and thiols, respectively. A versatile reaction conditions to generate Pummerer intermediate were examined. The best condition was the combination of trifluoroacetic anhydride with stannic chloride. All reactions may involve an initial formation of α-phosphoryl thiocarbocation and a subsequent nucleophilic attack of aromatic compounds and thiols.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.693-696
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• 2011

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.05a
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• pp.93-93
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• 2002

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.885-886
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• 2003

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1135-1142
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• 1996

Reaction of diethylzinc with α-branched aldehydes in the presence of a catalytic amount (5 mol %) of various β-amino thiols in toluene or ether provided the corresponding secondary alcohols in outstanding ee. Detailed preparative procedure for the β-amino thiols are presented.