• Radiation Oncology Journal
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• v.31 no.2
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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.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3209-3212
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• 2014

This paper describes a selective synthetic method of fabricating Ag nanowires by using a modified polyol process. To synthesize the Ag nanowire, an ethylene glycolic solution of silver nitrate and an ethylene glycolic solution of polyvinylpyrrolidone solution containing a small amount of organic oxidant, 1,4-benzoquinone, were slowly added to a hot ethylene glycol medium at $160^{\circ}C$ for 8 min using a syringe pump. The reaction mixtures were heated for an additional 45 min and cooled to room temperature. Finally, the silver nanomaterials were isolated from the mixture by centrifugation. The crystal structure of the nanomaterials was investigated by powder X-ray diffraction analyses, and their morphology was investigated by scanning electron microscopy. A small amount of organic oxidant, 1,4-benzoquinone, played a significant role in controlling the morphology during crystal growth. Consequently, Ag nanowires rather than Ag nanoparticles were selectively obtained.

• Textile Coloration and Finishing
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• v.3 no.1
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• pp.28-36
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• 1991

Thermotropic behavior was observed in a number of aromatic copoly (ester amide)s containing a flexible spacer based on 4,4'$-dicarboxyalpha,\varpi-diphenoxy$ alkanes as an A component, di-acetylated p-aminophenol as a B, di-acetylated hydroquinone as a C gave the thermotropic copoly (ester amide)s containing a flexible spacer in the polymer backbone. 4,4'-diamino-3,3'-dimethoxybiphenyl as an amino group containing monomer as a D components. In the last case, up to 60 mol% of amide group was allowed to afford thermotropic liquid-crystallinity. The polymer structure and thermotropic nature were examined by solid-state and solution $^{13}C$ NMR spectroscopy, differential scanning calorimeter, polarizing microscopy, and IR spectroscopy.

• Natural Product Sciences
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• v.26 no.4
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• pp.303-310
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• 2020

Four new merohexapenoids named calyxaprenols A-D (1 - 4), together with the known compound haliclotriol A (5), have been isolated from the marine sponge Calyx sp. which was collected from the southwest islands of Palau. Based on comprehensive spectroscopic analyses, calyxaprenols A (1) and B (2) were determined to be pentacyclic hexaprenoids that are appended to a glycolic acid-substituted phenol moiety, whereas calyxaprenols C (3) and D (4) possess a tricyclic hexaprenoid skeleton joined to a hydroquinone ring. Identification of new merohexaprenoids from a Calyx sponge expands the known taxonomic distribution of this sparsely distributed class of marine metabolites and increases the chemical diversity described for this genus of marine sponge.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.904-909
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• 1994

Cure kinetics of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline)/GN(glutaronitrile) system with and without HQ(hydroquinone) as a catalyst was studied by Kissinger equation and Fractional life method. The activation energy of the system with HQ was somewhat lower and the pre-exponential factor of that was higher by about 30% than those of the system without HQ. As 1.25phr of HQ was added, reaction rates increased about 1.8 times.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.459-469
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• 1995

As S-nitrosothiols were proposed as nitrergic carriers in vascular and nonvascular smooth muscle, we have investigated the relaxant properties of several S-nitrosothiols in the porcine retractor penis(PRP) muscle and compared them with the effects of exogenously added NO, electrical field stimulation(EFS) of NANC nerves and sodium nitroprusside(SNP). Also the influences of oxyhemoglobin and hydroquinone on the relaxant responses were investigated. In addition, effects of NO on membrane potentials and its involvement in the generation of inhibitory junction potential(IJP) were investigated with conventional intracellular microelectrode technique. The results were summerized as follows. 1. Frequency-dependent relaxations of PRP muscle were induced by EFS to NANC nerve. Tetrodotoxin($1{\times}10^{-6}M$) abolished the relaxations of PRP muscle induced by EFS, and L-NAME(($2{\times}10^{-5}M$) and methylene blue($4{\times}10^{-5}M$) inhibited the relaxations. L-NAME-induced inhibition of the relaxations was reversed by L-arginine($1{\times}10^{-3}M$), but not by D-arginine. 2. Exogenous NO($1{\times}10^{-5}-1{\times}10^{-4}M$), sodium nitroprusside(($1{\times}10^{-7}-1{\times}10^{-4}M$) induced dose-dependent relaxations of PRP muscle. All S-nitrosothiols($1{\times}10^{-7}-1{\times}10^{-4}M$) tested relaxed the PRP muscle in dose-dependent manner and the potency order was SNAP>GSNO>CysNO>SNAC. 3. Oxyhemoglobin($5{\times}10^{-5}M$) blocked the relaxation induced by exogenous NO and inhibited EFS-, S-nitrosothiols-, and SNP-induced relaxation. 4. Hydroquinone($1{\times}10^{-4}M$) also abolished the relaxations induced by exogenous NO, and reduced the relaxations induced by S-nitrosothiols, but did not affect EFS- and SNP-induced relaxations. 5. SNP($2{\times}10^{-6}-5{\times}10^{-6}M$) relaxed muscle strips but the membrane potentials were not affected. 6. EFS with several pulses(1ms, 2Hz, 80V) produced an inhibitory junction potential(IJP) with muscle relaxation. They were abolished by TTX($2{\times}10^{-6}M$). $N^G$-nitro-$_{\small{L}}$-arginine(L-NNA, $2{\times}10^{-5}M$) abolished the muscle relaxation, but had no effect on IJP.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.284-292
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• 1977

Epoxy-methacrylate prepolymer was synthesized from methacrylic acid and a diglycidyl ether type low molecular weight epoxy resin, and the electron beam curing of the prepolymer was studied using styrene and polyethyleneglycol dimethacrylates as comonomers. The esterification was carried out quantitatively without any side reaction adding more than 250∼300ppm hydroquinone and less than $1{\%}$ (wt) triethanolamine by wt. of methacrylate acid, respectively. In the radiation curing under air atmosphere, the maximum gel fraction was observed at 10∼$30{\%}$ monomer contents. The rate of gel formation was decreased by the presence of unreacted epoxy group and acid in the prepolymer and increased with increasing degree of polymerization of polyethyleneglycol block in the dimethacrylates. Considerable oxygen effect in the curing, particularly when polyethyleneglycol dimethacrylate was used as a comonomer, was recognized through the differences of the product properties, though no remarkable differences were found in the rate of gel formation in air and nitrogen atmosphere.

• Korean journal of applied entomology
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• v.7
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• pp.61-64
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• 1969

By way of paper chromatography, free sugars in pycnial drops of Gymnosporangium haraeanum Sydow were investigated in regard of their biochemical interrelation with free sugars of Chinese juniper and pear leaf. The free sugar in pycnial drops of Gynnosporangium haraeanum Sydow were identified to only Fructose spot. Free sugars in Chinese juniper leaf were identified to Glucose. Galactose and two unknown spots. Free sugars of another sample in pear leaf were identified to spots of Glucose, Furctose and Galactose. The Arbutin from pear leaf was crystalized and its structure was identified to Glucose and Hydroquinone. The acetone powder of Emulsin was incubated for 1 hour at $40^{\circ}C$ with 0.05 M Arbutin substrate in test tube and purified by general method with the purpose of analysis of its. metabolic products. And the paper chromatographic analysis showed it to be Glucose spot. From the above results, this Fructose in pycinal drops of Gymnosporangium haraeanum Sydow is presumed to be the exchangeable from free sugars in pear leaf or to be the hydrolyzed of $\beta-glycoside$ (Arbutin)-the metabolic isomerization of Glucose into Fructose by pycnia isomerase.

• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.101-104
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• 1986

Dialdehydes such as adipaldehyde, glutaraldehyde, and succinaldehyde were readily reduced to give their corresponding 1,6-hexanediol, 1,5-pentanediol, and 1,4-butanediol in good yields in the presence of catalytic amount of hexarhodium hexadecacarbonyl or iron pentacarbonyl in water and methoxyethanol or ethanol at 180$^{\circ}C$ for 4 hr under carbon monoxide atmosphere. Under the same reaction conditions, diketones such as 2,5-hexanedione, 2,4-pentanedione, and 2,3-butanedione afforded their corresponding 2,5-hexanediol, 2,4-pentanediol and 2,3-butanediol in moderate yields. For double hydrohydroxymethylation of dialdehydes or diketones, rhodium or iron carbonyl complexes are more effective than others. Particularly, benzoquinone gave hydroquinone quantitatively.

• Applied Biological Chemistry
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• v.27 no.4
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• pp.264-270
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• 1984

In order to obtain mutagenic data of enzymatic browning reaction products, we investigated their mutagenicity. The rec-assay with Bacillus subtilis strains $H17(rec^+)$ and $M45(rec^-)$ were carried out with their spores. Detection of double strand breakage in calf-thymus DNA was investigated into sample solution with and without $Cu^{2+}$ by the agarose slab gel electrophoresis. In the rec-assay, catechol, pyrocatechol, DL-dopa, 3,4-dihydroxytoluene, hydroquinone, hydroxyhydroquinone with and without $Cu^{2+}$ in 0.05M ana 0.1M at the enzymatic browning reaction products stowed mutagenic action. And also browning solution of 0.05M hydroxyhydroquinone and catechol with $Cu^{2+}$, hydroquinone with and without $Cu^{2+}$ of 0.1M at the enzymatic browning reaction products were strong mutagenic action. The DNA breakability of the enzymatic browning reaction products of 0.1M pyrogallol was stronger than that of 0.05M pyrogallol browning solution with $Cu^{2+}$ and 3,4-dihydroxytoluene browning solution was stronger than that of 0.01M 3,4-dihydroxytoluene browning solution.