• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2446-2450
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• 2013

Oxindole dimers have been used as intermediates in the synthesis of various cyclotryptamine alkaloids. An efficient direct synthesis of oxindole dimers has been carried out from 3-substituted oxindoles via an oxidative dimerization using manganese(III) acetate or copper acetate/silver acetate system.

• Archives of Pharmacal Research
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• 제22권3호
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• pp.306-308
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• 1999

The oxidative dimerization of ferulic acid has been carried out using horse-radish peroxidase as catalyst to give a dihydrobenzofuran neolignan (1), the structure of which was elucidated as (2SR, 3RS)-2,3-dihydro-2-(4-hydroxy-3-methoxyphenyl)-3n-butoxycarbonyl-5-(2E-carboxyethenyl)-7methoxybenzofuran by spectroscopic analyses. This compound showed more potent cytotoxicity against several tumor cell lines than the starting material.

• Bulletin of the Korean Chemical Society
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• 제16권12호
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• pp.1148-1152
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• 1995

Oxidative dimerization of methane to C2-hydrocarbons was performed over lead aluminate spinel catalysts. These spinel catalysts were prepared by co-precipitation, aerogel, and sol-gel methods. The active phase of lead aluminate oxides was found to be PbAl2O4 spinel. The activities of the catalysts were strongly dependent on the preparation method as well as the composition of PbAl2O4 phase. The proper oxygen mobility of PbAl2O4 spinel oxides appeared to be important to get high catalytic activity and selectivity for C2-hydrocarbon formation.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.107-109
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• 2008

Medicinal fungi, Phellinus linteus and Inonotus xeranticus, produce a cluster of yellow pigment in their fermentation broth that acts as an important element of biological activity. The pigment is composed of diverse polyphenols with a styrylpyrone moiety, mainly hispidin and its dimers, 3,14'-bihispidinyl, hypholomine B, and 1,1-distyrylpyrylethan. Although dimeric hispidins were proposed to be biosynthesized from two molecules of monomer via oxidative coupling by ligninolytic enzymes, laccase and peroxidase, the details of this process remain unknown. In this preliminary study, we attempted to achieve enzymatic synthesis of the hispidin dimer from hispidin by using commercially available horseradish peroxidase (HRP). Consequently, a hispidin dimer, 3,14'-bihispidinyl, was synthesized, whereas the other dimers, hypholomine B and 1,1-distyrylpyrylethan, were not produced. This result suggested that the oxidative coupling at the C-3 and C-14' positions of hispidins was dominant in the process of dimerization by HRP, and indicated that additional catalysts or substrates would be needed to synthesize other hispidin dimers present in the fungal metabolite.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1566-1571
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• 2007

생리학적 활성을 가지고 있을 것으로 예측되는 디-아세틸렌 결합으로 연결된 oligodeoxyribonucleotide를 합성하였다. Pd(0)촉매를 사용한 Heck-type C-C 결합반응을 통하여 2'-deoxyuridine의 5-위치에 acetylene 기를 도입하고, 5'-OH를 t-butyldimethylsilyl로 보호한 후, Glaser oxidative coupling 반응을 이용하여 dimerization을 시켰다.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.711-714
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• 2004

Peroxynitrite enters erythrocytes through band 3 anion exchanger and oxidizes cytosolic proteins therein. As a protein associated with band 3, carbonic anhydrase II may suffer from peroxynitrite-induced oxidative damages. Esterase activity of carbonic anhydrase II decreased as the concentration of peroxynitrite increased. Neither hydrogen peroxide nor hypochlorite affected the enzyme activity. Inactivation of the enzyme was in parallel with the release of zinc ion, which is a component of the enzyme's active site. SDS-PAGE of peroxynitrite-treated samples showed no indication of fragmentation but non-denaturing PAGE exhibited new bands with lower positive charges. Western analysis demonstrated that nitration of tyrosine residues increased with the peroxynitrite concentration but the sites of nitration could not be determined. Instead MALDI-TOF analysis identified tryptophan-245 as a site of nitration. Such modification of tryptophan residues is responsible for the decrease in tryptophan fluorescence. These results demonstrate that peroxynitrite nitrates tyrosine and tryptophan residues of carbonic anhydrase II without causing fragmentation or dimerization. The peroxynitrite-induced inactivation of the enzyme is primarily due to the release of zinc ion in the enzyme's active site.

• Molecules and Cells
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• 제24권2호
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• pp.224-231
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• 2007

$H_2O_2$, as an example of oxidative stress, induces cardiac myocyte apoptosis. Bcl-2 family proteins are key regulators of the apoptotic response while their functions can be regulated by post-translational modifications including phosphorylation, dimerization or proteolytic cleavage. In this study, we examined the role of various protein kinases in regulating total BAD protein levels in adult rat cardiac myocytes undergoing apoptosis. Stimulation with 0.1 mM $H_2O_2$, which induces apoptosis, resulted in a marked down-regulation of BAD protein, which is attributed to cleavage by caspases since it can be restored in the presence of a general caspase inhibitor. Inhibition of PKC, p38-MAPK, ERK1/2 and PI-3-K did not influence the reduced BAD protein levels observed after stimulation with $H_2O_2$. On the contrary, inhibition of PKA or specifically $PKC{\delta}$ resulted in up-regulation of BAD. Decreased caspase 3 activity was observed in $H_2O_2$ treated cells after inhibition of PKA or $PKC{\delta}$ whereas inhibition of PKA also resulted in improved cell survival. Furthermore, addition of okadaic acid to inhibit selected phosphatases resulted in enhanced BAD cleavage. These data suggest that, during oxidative stress-induced cardiac myocyte apoptosis, there is a caspase-dependent down-regulation of BAD protein, which seems to be regulated by coordinated action of PKA, $PKC{\delta}$ and phosphatases.

• Molecules and Cells
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• 제37권1호
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• pp.43-50
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• 2014

Jumonji domain-containing proteins (JMJD) catalyze the oxidative demethylation of a methylated lysine residue of histones by using $O_2$, ${\alpha}$-ketoglutarate, vitamin C, and Fe(II). Several JMJDs are induced by hypoxic stress to compensate their presumed reduction in catalytic activity under hypoxia. In this study, we showed that an H3K27me3 specific histone demethylase, JMJD3 was induced by hypoxia-inducible factor (HIF)-$1{\alpha}/{\beta}$ under hypoxia and that treatment with Clioquinol, a HIF-$1{\alpha}$ activator, increased JMJD3 expression even under normoxia. Chromatin immunoprecipitation (ChIP) analyses showed that both HIF-$1{\alpha}$ and its dimerization partner HIF-$1{\beta}$/Arnt occupied the first intron region of the mouse JMJD3 gene, whereas the HIF-$1{\alpha}/{\beta}$ heterodimer bound to the upstream region of the human JMJD3, indicating that human and mouse JMJD3 have hypoxia-responsive regulatory regions in different locations. This study shows that both mouse and human JMJD3 are induced by HIF-1.

• 생명과학회지
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• 제21권5호
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• pp.664-670
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• 2011

Heat shock protein (HSP)은 외부적인 자극에 반응하여 세포를 보호하는 역할을 한다. 또한 HSP90은 혈관질환에서 처럼 세포가 사멸되거나 손상을 입는 경우 세포 밖으로 유리된다. 그러나 지금까지 세포 밖 HSP90이 혈관평활근세포에 어떠한 영향을 주는지에 대한 연구는 미약하다. 따라서 본 연구는 혈관평활근세포에서 HSP90이 CXCL10 발현에 대한 영향과 그 기전을 규명하였다. HSP90에 노출된 혈관평활근세포에서 CXCL10 transcript가 증가하고, CXCL10 단백질의 분비가 증가되었다. HSP90에 의한 CXCL10 분비는 Toll-like receptor (TLR)-2/-4 억제제인 1-palmitoyl-2-arachidonosyl-sn-phosphatidylcholine (OxPAPC)과 NADPH oxidase 억제제인 diphenyleneiodium 그리고 Akt 경로를 억제하는 LY294002와 Akti IV에 의하여 크게 감소되었다. 또한 TLR-4의 dimerization을 저해하는 curcumin 역시 HSP90에 의한 CXCL10의 분비를 억제하였다. 전사인자인 nuclear factor kappa B(NF-${\kappa}$B)의 생물학적 억제제인 inhibitory kappa B (I${\kappa}$B)와 NF-${\kappa}$B 억제작용이 있는 rasveratrol은 HSP90에 의한 CXCL10 분비를 억제하였다. 이러한 결과는 혈관평활근세포에서 HSP90에 의한 CXCL10의 발현에 TLR-4와 Akt 및 NF-${\kappa}$B가 관여함을 의미한다.

• Rapid Communication in Photoscience
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• 제3권4호
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• pp.70-72
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• 2014

Visible-light irradiation of MeCN solution containing di(hydroxo)metallo(tetraphenyl)porphyrin complex $(tppM(OH)_2$: 1a; $M=Sb(V)^+Br^-$, 1b; $M=P(V)^+Cl^-$, 1c; M=Ge(IV)) and 2-mercaptoethanol (2-ME) as a substrate under aerated condition gave bis(2-hydroxyethyl)disulfide (2-HEDS) as an oxidative product of 2-ME. It is indicated that the oxidation of 2-ME should proceed with a photocatalytic process by 1, because the turn over number (TON) for the formation of 2-HEDS was over unit. The TON was determined to be 642 as a maximum value when 1a was used as a sensitizer. The formation of 2-HDES was extremely slow under argon atmosphere. The fluorescence of 1 was not quenched by 2-ME at all, and the free energy change (${\Delta}G$) with electron transfer (ET) from 2-ME to excited triplet state of $1(^31^*)$ was estimated as a negative value. The quenching rate constant ($k_r$) of $^31^*$ by 2-ME, obtained by the kinetics for the formation of 2-HEDS, strongly depends on ${\Delta}G$. These findings indicate that 1-sensitized oxidation was initiated by photoinduced ET from 2-ME to $^31^*$ to generate both radical cation of 2-ME ($2-ME^{+\bulle}$) and porphyrin radical anion ($1^{-\bulle}$), resulting that the formation of 2-HEDS can be proceeded by the dimerization of $2-ME^{+\bulle}$, and through a catalytic cycle due to returning to 1 by the ET from $1^{-\bulle}$ to molecular oxygen.