• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.915-920
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• 2008

In this paper the electrochemical behaviors of hydroquinone ($H_2Q$) were investigated on a carbon paste electrode using room temperature ionic liquid N-butylpyridinium hexafluorophosphate ($BPPF_6$) as binder (ILCPE) and further applied to $H_2Q$ determination. In pH 2.5 phosphate buffer solution (PBS), the electrochemical response of H2Q was greatly improved on the IL-CPE with a pair of well-defined quasi-reversible redox peaks appeared, which was attributed to the electrocatalytic activity of IL-CPE to the $H_2Q$. The redox peak potentials were located at 0.340 V (Epa) and 0.240 V (Epc) (vs. the saturated calomel electrode, SCE), respectively. The formal potential ($E^0$') was calculated as 0.290 V and the peak-to-peak separation (${\Delta}E_p$) was 0.100 V. The electrochemical parameters of $H_2Q$ on the IL-CPE were further calculated by cyclic voltammetry. Under the selected conditions the anodic peak current was linear with $H_2Q$ concentration over the range from $5.0\;{{\times}}\;10^{-6}$ to $5.0\;{\times}\;10^{-3}\;mol\;L^{-1}$ with the detection limit as $2.5\;{\times}\;10^{-6}\;mol\;L^{-1}$ (3$\sigma$ ) by cyclic voltammetry. The proposed method was successful applied to determination of $H_2Q$ content in a synthetic wastewater sample without the interferences of commonly coexisting substances.

• 분석과학
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• 제9권3호
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• pp.235-243
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• 1996

${\alpha}$-Cyclodextrin을 사용하여 carbon paste 전극을 화학수식하였다. 화학수식전극의 특성은 P-니트로페놀과 ${\alpha}$-cyclodextrin과의 포함복합체형성을 기초로 연구하였다. 화학수식효과를 보기 위해 순환전압전류법과 시차펄스전압전류법을 사용하였다. ${\alpha}$-Cyclodextrin과 탄소분말을 2:1 의 비율로 섞은 전극에서 환원에 의한 봉우리 전류는 o-니트로페놀이나 히드로퀴논의 경우에 비해 p-니트로페놀의 경우 거의 완전히 사라졌다. 이는 p-니트로페놀과 ${\alpha}$-cyclodextrin간의 강한 포함복합체형성에 의한 것이다. 이 전극을 이용하여 p-니트로페놀 존재하에서 o-니트로페놀을 정량할 수 있었다.

• The Korean Journal of Physiology and Pharmacology
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• 제21권3호
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• pp.345-352
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• 2017

Since previous studies have reported that hydroquinone (HQ) exerted immunosuppressive and anti-inflammatory activity, various HQ derivatives have been synthesized and their biological activities investigated. In this study, we explored the anti-inflammatory activity of JS-III-49, a novel HQ derivative, in macrophage-mediated inflammatory responses. JS-III-49 suppressed the production of the inflammatory mediators nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) and down-regulated the mRNA expression of the inflammatory enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) as well as the expression of the pro-inflammatory cytokines interleukin-6 (IL-6) and IL-$1{\beta}$ without cytotoxicity in LPS-stimulated RAW264.7 cells. JS-III-49 inhibited nuclear translocation of the $NF-{\kappa}B$ transcription factors p65 and p50 by directly targeting Akt, an upstream kinase of the $NF-{\kappa}B$ pathway, in LPS-stimulated RAW264.7 cells. However, JS-III-49 did not directly inhibit the kinase activities of Src and Syk, which are upstream kinases of Akt, in LPS-stimulated RAW264.7 cells. Moreover, JS-III-49 suppressed the nuclear translocation of c-Fos, one of the components of AP-1, by specifically targeting p38, an upstream mitogen-activated protein kinase (MAPK) in the AP-1 pathway in LPS-stimulated RAW264.7 cells. These results suggest that JS-III-49 plays an anti-inflammatory role in LPS-stimulated macrophages by targeting Akt and p38 in the $NF-{\kappa}B$ and AP-1 pathways, respectively.

• 대한화학회지
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• 제51권6호
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• pp.585-590
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• 2007

• 전기화학회지
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• 제6권2호
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• pp.130-133
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• 2003

3,4-dihydroxybenzoic acid(3,4-DHBA)를 전기화학법으로 유리탄소 전극 위에 중합하여 GC/p-3,4-DHBA형의 전극을 제작한 후 이 전극을 도파민으로 재 수식한 전극을 제작하였다. 이 때 고분자 피막 상에 카르복시기와 도파민의 아민 기간에 짝 짓기 반응은 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride(EDC)의 존재하에서 진행되었다. 이 반응과정에서 반응한 도파민의 양은 수정판 분석기(quartz crystal analyzer:QCA)에 의하여 결정하였으며 그때 전극형태는 QCA(Au)/p-3,4-DHBA-dopamine이었다. 이 전극의 표면은 o-퀴논부분을 갖고 있어서 티탄이온에 선택성이 큰 특성을 갖고 있다. 이 전극의 산화환원과정은 $hydroquinone = quinone +2H^+2e^-$으로 두 개의 강한 파와 두개의 약한 파가 CV과정에서 관찰되었다. 이 수식전극으로 Ti(IV)이온을 $4.13\times10^{-5} gcm^{-2}$만큼 포집할 수가 있었다. 이 수식 전극으로 $5.25\times10^{-4}M$에서 $5.25\times10^{-8}M$농도범위까지 정량 할 수 있는 상관계수가 0.997인 검정선을 얻었다.

• Radiation Oncology Journal
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• 제31권2호
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• pp.57-65
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• 2013

Beta-lapachone (${\beta}$-Lap; 3,4-dihydro-2, 2-dimethyl-2H-naphthol[1, 2-b]pyran-5,6-dione) is a novel anti-cancer drug under phase I/II clinical trials. ${\beta}$-Lap has been demonstrated to cause apoptotic and necrotic death in a variety of human cancer cells in vitro and in vivo. The mechanisms underlying the ${\beta}$-Lap toxicity against cancer cells has been controversial. The most recent view is that ${\beta}$-Lap, which is a quinone compound, undergoes two-electron reduction to hydroquinone form utilizing NAD(P)H or NADH as electron source. This two-electron reduction of ${\beta}$-Lap is mediated by NAD(P)H:quinone oxidoreductase (NQO1), which is known to mediate the reduction of many quinone compounds. The hydroquinone forms of ${\beta}$-Lap then spontaneously oxidizes back to the original oxidized ${\beta}$-Lap, creating futile cycling between the oxidized and reduced forms of ${\beta}$-Lap. It is proposed that the futile recycling between oxidized and reduced forms of ${\beta}$-Lap leads to two distinct cell death pathways. First one is that the two-electron reduced ${\beta}$-Lap is converted first to one-electron reduced ${\beta}$-Lap, i.e., semiquinone ${\beta}$-Lap $(SQ)^{{\cdot}-}$ causing production of reactive oxygen species (ROS), which then causes apoptotic cell death. The second mechanism is that severe depletion of NAD(P)H and NADH as a result of futile cycling between the quinone and hydroquinone forms of ${\beta}$-Lap causes severe disturbance in cellular metabolism leading to apoptosis and necrosis. The relative importance of the aforementioned two mechanisms, i.e., generation of ROS or depletion of NAD(P)H/NADH, may vary depending on cell type and environment. Importantly, the NQO1 level in cancer cells has been found to be higher than that in normal cells indicating that ${\beta}$-Lap may be preferentially toxic to cancer cells relative to non-cancer cells. The cellular level of NQO1 has been found to be significantly increased by divergent physical and chemical stresses including ionizing radiation. Recent reports clearly demonstrated that ${\beta}$-Lap and ionizing radiation kill cancer cells in a synergistic manner. Indications are that irradiation of cancer cells causes long-lasting elevation of NQO1, thereby sensitizing the cells to ${\beta}$-Lap. In addition, ${\beta}$-Lap has been shown to inhibit the repair of sublethal radiation damage. Treating experimental tumors growing in the legs of mice with irradiation and intraperitoneal injection of ${\beta}$-Lap suppressed the growth of the tumors in a manner more than additive. Collectively, ${\beta}$-Lap is a potentially useful anti-cancer drug, particularly in combination with radiotherapy.

• 한국결정학회지
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• 제2권2호
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• pp.13-21
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• 1991

50% terephthaloyl chloride(TPA)와 50%(1-phenylethyl) hydroquinone(PEHQ)으로부터 합성된 열 액정폴리에스터 poly(1-phenylethyl-p-phenylene-terephthalate)의 chalk conformation 및 packing 상태를 X-선 회절법을 이용하여 해석하였다. 단위세포상수는 a=12.77 A, b=10.17 A(unlque axis), c=12.58 A (fiber axis), β=90.1°, 그리고 공간군은 P2l 이고 단사정계이며 Z:4 이었다. 미세구조는 주쇄상의 Phenyl-COO 그리고 COO-Phenyl 평면간의 그리고 주축과 측쇄간의 torsion angle 들을 중심으로 37개의 회절반점에 대해 Linked Atom Least Square(LALS) 방법을 이용하여 해석하였으며, 1-phenylethyl 치환체는 ortho-와 met a위치에 각각 확률적으로 0.5의 가중치를 부여함에 의해 구조적으로 모델링 되었다. 주쇄상의 Phenyl-COO그리고 Phenyl-COO평면간의 torsion angle은 각각 -6.1°와 65.6°로 주어졌으며 결국 주축상의 Phenol 평면들은 서로 59.5°로 엇갈려 주축을 형성하고 있음을 알 수 있었다. (단 ester, COO-, 기는 평면으로 가정되었다.)

• 폴리머
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• 제25권6호
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• pp.782-788
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• 2001

$[Ru(v-bpy)_3]^{2+}$와 vinylbenzoic acid(vba)의 공중합 피막전극에 dopamine을 반응시켜 수식된 전극을 제작하고 이 고분자의 중합속도와 산화-환원 및 전자전달 특성을 연구하였다. 두 단량체의 몰비가 5:2일 때 공중합속도 상수는 $1.84{ imes}10^{-2}s^{-1}$이고 중합된 피막상에서 두 성분비는 5:1.68이였다. GC/p-$[Ru(V-bpy)_3]^{2+}$/vba-dopamine형의 수식된 전극에서 hydroquinone=quinone+$2H^+2e^-$의 전극반응에 의한 형식전위는 인산염완충용액(pH=7.10)에서 0.17 V이며, 전기촉매반응에서 속도상수($K_{ch}{Gamma}$)는 $2.58{ imes}10^5cms^{-1}$로서 수식되기 전보다 2.41배 큰 값이다. EQCM법에 의한 산화-환원과정에서 질량변화는 수식되기 전보다 $3.28{ imes}10^3$$gmol^{-1}$ 더 크다.

• 한국식품과학회지
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• 제22권6호
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• pp.618-624
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• 1990

사과(Jona gold)로부터 추출한 polyphenol oxidase와 polyphenol 화합물인 catechol, hydroquinone, homocatechol, hydroxyhydroquinone 그리고 pyrogallol 용액과 반응시켜 얻어진 사과효소 갈변반응 생성물에 대한 항돌연변이원성 효과를 검토하였다. SOS spot test와 SOS chromotest에 사용된 균주는 E. coli PQ37/plasmid pKM101 균주이며 spot test에서 위 다섯 종류의 시료 모두 갈변용액의 농도를 증가시켜 줌에 따라서 mitomycin C(MMC), 4-nitroquinoline-1-oxide(4NQO), 그리고 N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) 등의 발암물질들에 대해서 강한 억제활성을 나타내었다. 한편, SOS chromotest에서도 발암물질의 종류에 따라 차이는 있으나 갈변용액의 농도증가에 따라 MMC, MNNG, 4 NQO 그리고 3-amino-1,4-dimethyl-5H-pyrido-(4,3-b) indol (Trp-P-1) 등에 대해서 강한 억제활성을 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.509-514
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• 1989

Reactions of thianthrene cation radical perchlorate (1) with N-(p-methoxyphenyl)benzenesulphonamide (14) in acetonitrile at room temperature afforded various products : thianthrene (3), N-(p-hydroxyphenyl)benzenesulphonamide (16), benzenesulphonamide (18), hydroquinone (20); 5-(5-benzenesulphonamido-2-methoxyphenyl)-thia nthrenium perchlorate(21), 2-benzenesulphonamido-2'-hydroxy-5,5'-dimethoxy biphenyl(24), 2-benzenesulphonamido-2',5'-dihydroxy-5-methoxy -biphenyl(25), and a traceable amount of p-quinone(23). The formations of part of (3) and (21) can be explained by either disproportionation or half-regeneration mechanism but those of the remainders by diverse reactions of sulphonamidyl radical (27) derived from (14) (through single electron transfer, followed by deprotonation processes). Similar results were observed from the reaction with N-(p-methoxyphenyl)methanesulphonamide (15).