酚化合物对胰岛素淀粉样纤维化的抑制作用

采用牛胰岛素作为模型多肽分子, 对几种结构相近的简单多酚的抗多肽淀粉样纤维化作用进行了研究. 结果表明, 邻苯二酚和对苯二酚对胰岛素纤维化具有抑制作用, 并通过形成醌中间体对多肽链进行修饰, 与对苯醌作用类似; 而苯酚和间二苯酚在相同条件下, 既不能修饰多肽也无抑制纤维化作用. 在无氧条件下, 邻苯二酚和对苯二酚对胰岛素纤维化的抑制作用明显降低, 说明酚化合物经氧化形成的醌中间体是其抗胰岛素纤维化的主要活性结构.     

Flow injection chemiluminescence analysis of phenolic compounds using the NCS-luminol system

A flow injection system coupled with two simple and sensitive chemiluminescence (CL) methods is described for the determination of some phenolic compounds. The methods are based on the inhibition effects of the investigated phenols on the CL signal intensities of N-chlorosuccinimide-KI-luminol (NCS-KI-luminol) and NCS-luminol systems. The influences of the chemical and hydrodynamic parameters on the decrease in CL signal intensities of NCS-KI-luminol and NCS-luminol systems for hydroquinone, catechol, and resorcinol, serving as the model compounds of analyte, were studied in the flow injection mode of analysis. Under the selected conditions, the proposed CL systems were used for the determination of some phenolic compound and analytical characteristics of the systems including calibration equation, correlation coefficient, linear dynamic range, limit of detection, and sample throughput. The limits of detection for hydroquinone, catechol, and resorcinol were 0.002, 0.01, and 0.3 μM using the NCS-KI-luminol system; for the NCS-luminol system these were 0.01, 0.17, and 1.6 μM, respectively. The relative standard deviation for 10 repeated measurements of 0.04, 0.06, and 1 μM of hydroquinone, catechol, and resorcinol were 1.9, 1.4, and 2.0%, respectively, with the NCS-KI-luminol system; for 0.2, 0.5, and 4 μM of hydroquinone, catechol, and resorcinol these were 2.6, 2.2, and 3.7%, respectively, using the NCS-luminol system. The method was applied to the determination of catechol in known environmental water samples with a relative error of less than 6%. A possible reaction mechanism of the proposed CL system is discussed briefly.      

Flow injection analysis of resorcinol using inhibited Rhodamine B/Cerium(IV) chemiluminescence system

The fluorescent dye Rhodamine B (RhB), in combination with a strong oxidant Ce(IV), was used to investigate the properties of three important polyphenols, resorcinol, catechol, and hydroquinone. The reaction of RhB with Ce(IV) solution in acidic medium was found to elicit strong chemiluminescence (CL). The CL signal remarkably weakened in the presence of resorcinol whereas the two other isomers, catechol, and hydroquinone, hardly had any effect in the same range of concentrations. Based on these observations, a new flow-injection CL method was developed for the determination of resorcinol. In addition, a brief discussion of possible mutual interaction mechanism between the three polyphenols and the components of the system is also presented. The article is published in the original.     

High-performance liquid chromatographic determination of phenolic compounds in natural water coupled with on-line flow injection membrane extraction-preconcentration

A liquid chromatographic method for determination of trace phenolic compounds has been established, coupled with an on-line supported liquid membrane extraction-preconcentration flow-injection system. Tributyl-phosphate dissolved in kerosene was used as the carrier of the supported liquid membrane. Four phenolic compounds (phenol, catechol, resorcinol and hydroquinone) were chosen as the model compounds and the experiment conditions were optimized. Under the optimum conditions, calibrations were linear in the range of 1-500 microg/L, with good correlation coefficients (r > 0.999). The total analysis time of the system was 22 min, including the membrane extraction, liquid chromatographic separation and equilibration times.     

Separation and quantitation of phenolic compounds in mainstream cigarette smoke by capillary gas chromatography with mass spectrometry in the selected-ion mode

Cigarette smoke condensate is a complex chemical matrix and determination of phenolic compounds in it frequently requires extensive and laborious sample preparation. By utilizing derivatization techniques and capillary column gas chromatography with mass spectrometry in the selected-ion mode, separation and quantitation of selected phenolic compounds found in mainstream cigarette smoke can be accomplished with minimal sample preparation. This method has been used to determine concentrations of phenol, o-cresol, m-cresol, p-cresol, catechol, resorcinol and hydroquinone in cigarette smoke condensate from a number of commercially available cigarettes and a new cigarette which heats, but does not burn, tobacco. Unlike tobacco-burning cigarettes, levels of the phenolic compounds in the new cigarette smoke are at or below the detection limits for most of the compounds. This result is attributed to the unique design of the new cigarette.     

Molecularly imprinted polymers microsphere prepared by precipitation polymerization for hydroquinone recognition

A one-step precipitation polymerization synthesis was adopted for the preparation of molecularly imprinted polymers (MIPs) by using hydroquinone as a template molecule. The transmission electron microscopy (TEM) exhibited that the polymers were uniform spheres with the diameter of about 700 nm. The results of adsorption experiments showed that the microspherical imprinted polymers possessed fast adsorption dynamics. Compared to the structurally similar compounds, catechol and resorcinol, the MIPs exhibited a high recognizable capacity to hydroquinone. And the electrochemical sensor fabricated by modifying the prepared MIPs microsphere on the glassy carbon electrode surface was used to detect the hydroquinone concentration. The current response was proportional to the concentration of hydroquinone in the range of 2.0 x 10(-6) to 1.0 x 10(-4)mol/L with the detection limit of 1.0 x 10(-6)mol/L.     

Optical detection of phenolic compounds based on the surface plasmon resonance band of Au nanoparticles

An indirect colorimetric method is presented for detection of trace amounts of hydroquinone (1), catechol (2) and pyrogallol (3). The reduction of AuCl4(-) to Gold nanoparticles (Au-NPs) by these phenolic compounds in the presence of cetyltrimethylammonium chloride (CTAC) produced very intense surface plasmon resonance peak of Au-NPs. The plasmon absorbance of Au-NPs allows the quantitative colorimetric detection of the phenolic compounds. The calibration curves derived from the changes in absorbance at lambda = 568 nm were linear with concentration of hydroquinone, catechol and pyrogallol in the range of 7.0 x 10(-7) to 1.0 x 10(-4)M, 6.0 x 10(-6) to 2.0 x 10(-4)M and 6.0 x 10(-7) to 1.0 x 10(-4)M, respectively. The detection limits were 5.3 x 10(-7), 2.5 x 10(-6) and 3.2 x 10(-7)M for the hydroquinone, catechol and pyrogallol, respectively. The method was applied satisfactorily to the determination of phenolic compounds in water samples and pharmaceutical formulations.     

The adsorption of resorcinol from water using multi-walled carbon nanotubes

Adsorption of resorcinol and other phenolic derivatives on pristine multi-walled carbon nanotubes (MWCNTs) and HNO₃ treated MWCNTs has been investigated in attempt to explore the possibility to use MWCNTs as efficient adsorbents for pollutants. MWCNTs showed higher adsorption ability in a rather wide pH range of 4–8 for resorcinol, while decreased uptake capacity was found for acid-treated MWCNTs. Other phenolic derivatives such as phenol, catechol, hydroquinone and pyrogallol were employed to study the influence of the number and position of hydroxyl groups on the adsorption capacity. The amounts adsorbed by MWCNTs increased with the increasing number of hydroxyl. The substitution of phenol with a hydroxyl in meta-position leads to a much higher absorption ability than substitution in ortho- or para-position, which suggested that MWCNTs possess a great potential in removal of resorcinol from water, as well as the other phenolic derivatives.     

Determination of polyphenols by high-performance liquid chromatography with inhibited chemiluminescence detection.

A chemiluminescence reaction detector was developed for the detection of polyphenols separated by HPLC based on the inhibition of chemiluminescence from the luminol-potassium hexacyanoferrate(III) reaction by polyphenols. The separation was carried out on a RP-C18 column at 37 degrees C by using stepwise gradient elutions. The detection limits are in the range of 6.8 x 10(-7)-2.0 x 10(-9) g/ml for catechol, protocatechuic acid, chlorogenic acid, rutin, resorcinol, hydroquinone and p-tert.butylpyrocatechol. The method is sensitive, selective, fast and simple. It has been successfully applied to the determination of chlorogenic acid and rutin in real tobacco samples.     

Determination of major phenolic compounds in water by reversed-phase liquid chromatography after pre-column derivatization with benzoyl chloride

A simple reversed-phase LC method capable of detecting ng/ml quantities of phenolic compounds in water is described. Pre-column derivatization with benzoyl chloride is used for the separation and determination o-cresol, m-cresol, p-cresol, phenol, resorcinol, catechol and hydroquinone in water. The benzoyl derivatives formed within in 15 min, were extracted with dietyl ether, and then analyzed by liquid chromatography with UV detection at 232 nm. With a mobile phase of acetonitrile-tetrahydrofuran-water (54:6:40, v/v) the seven derivatives were eluted in 15 min. The detection limits were between 0.05 and 0.50 ng/ml for 50 ml of a standard water sample. The method was applied to the analysis of phenols in wine and river water. The recovery of the derivatives from pure water was 81-94% with relative standard deviations of 2.5-5.0%.     

超分子聚合机理

与共价键聚合物由单体(M1)通过共价键连接不同,超分子聚合物是由单体(M2)通过非共价键连接而成的长链大分子。聚合包括分子聚合和超分子聚合。超分子聚合描述M2通过非共价键自组装形成超分子聚合物的过程,涉及氢键、π-π堆砌型和立体匹配等驱动力以及分子识别、协同性等特征,与M1通过共价键形成聚合物的过程(分子聚合)不同。为了理解超分子聚合物链结构形成机理,本文分析和讨论超分子聚合的三个主要机理:(1)线性链生长;(2)螺旋链生长;(3)拓扑链生长。     

Inhibitory effects of catechol derivatives on arachidonic acid-induced aggregation of rabbit platelets

Pyrocatechol and other non-substituted dihydric phenols, which have strong redox power, inhibited arachidonic acid-induced aggregation of rabbit platelets at much lower concentrations than those at which these phenols inhibited stable prostaglandin endoperoxide, U46619-induced aggregation. Among non-substituted dihydric phenols, pyrocatechol was most potent. In order to clarify the physicochemical properties of the phenolic compounds which control the inhibitory potencies of dihydric phenols, we observed the inhibitory effects of 3- and 4-substituents of pyrocatechol on arachidonic acid-induced platelet aggregation. Among seven derivatives tested, the inhibitory effect of 4-C6H5-substituent was strongest and 4-COOH-substituent was weakest. Inhibitory effects of the catechol derivatives were well correlated with the quotients of their hydrophobicities and oxidation-reduction potentials. Inhibitory effects of hydroquinone and resorcinol were also on the same correlation line. These results suggest that the inhibitory effects of catechol derivatives and other dihydric phenols are controlled by two physicochemical properties: oxidation-reduction potential and hydrophobicity.     

Electroenzymatic reactions with oxygen on laccase-modified electrodes in anhydrous (pure) organic solvent

The electroenzymatic reactions of Trametes hirsuta laccase in the pure organic solvent dimethyl sulfoxide (DMSO) have been investigated within the framework for potential use as a catalytic reaction scheme for oxygen reduction. The bioelectrochemical characteristics of laccase were investigated in two different ways: (i) by studying the electroreduction of oxygen in anhydrous DMSO via a direct electron transfer mechanism without proton donors and (ii) by doing the same experiments in the presence of laccase substrates, which display in pure organic solvents both the properties of electron donors as well as the properties of weak acids. The results obtained with laccase in anhydrous DMSO were compared with those obtained previously in aqueous buffer. It was shown that in the absence of proton donors under oxygenated conditions, formation of superoxide anion radicals is prevented at bare glassy carbon and graphite electrodes with adsorbed laccase. The influence of the time for drying the laccase solution at the electrode surface on the electroreduction of oxygen was studied. Investigating the electroenzymatic oxidation reaction of catechol and hydroquinone in DMSO reveals the formation of various intermediates of the substrates with different electrochemical activity under oxygenated conditions. The influence of the content of aqueous buffer in the organic solvent on the electrochemical behaviour of hydroquinone/1,4-benzoquinone couple was also studied.     

高效液相色谱-高锰酸钾氧化化学发光法测定水中的痕量苯二酚

基于酸性介质中甲酸对高锰酸钾-苯二酚氧化发光反应的增敏作用建立了高效液相色谱-化学发光柱后检测苯二酚的新方法。优化了高锰酸钾-苯二酚氧化发光反应及高效液相色谱分离苯二酚的条件,用甲醇-0.1 mmol/L β-环糊精水溶液(体积比为30∶70) 作为流动相可实现对水中3种苯二酚异构体的分离,且能与高锰酸钾-苯二酚氧化化学发光反应条件很好地偶合。对所测定的苯二酚异构体,方法的线性范围达两个数量级;以信噪比为3测得邻、间、对苯二酚的检出限(n=3)分别为:5.2,4.7,3.2 μg/L,对质量浓度均为0.10 mg/L的3种苯二酚混合溶液连续测定11次,邻、间、对苯二酚的相对标准偏差分别为2.8%,3.4%,6.5%。将该方法与固相萃取技术相结合,对河水中的痕量苯二酚进行了测定,加标回收率为92.1%~95.4%。     

超高效液相色谱β-环糊精流动相添加剂法分析卷烟主流烟气中7种酚类化合物

以β-环糊精(β-CD)作为流动相添加剂,建立了一种超高效液相色谱(UPLC)快速分析卷烟主流烟气中对苯二酚、间苯二酚、邻苯二酚、苯酚、对甲酚、间甲酚、邻甲酚的方法。卷烟主流烟气中7种酚类化合物采用YC/T 255-2008标准方法收集,萃取液经0.22 μm微孔滤膜过滤后直接进行UPLC分析。采用ACQUIT UPLC BEH Shield RP18色谱柱,以含有4 g/L β-CD的流动相进行梯度洗脱,采用优化后的荧光检测条件进行检测,分析时间为10 min。实验结果表明: 与目前国内外普遍应用的HPLC方法相比,该方法实现了间甲酚和对甲酚异构体的有效分离,7种酚类化合物的荧光响应强度显著增加。7种酚类化合物在该方法的线性范围内线性关系良好(r＞0.9999), 3个加标水平上平均回收率为95.5%～103.5%,相对标准偏差(RSD)均小于4%,方法的检出限为4～14 ng/cig。     

The important role of quinic acid in the formation of phenolic compounds from pyrolysis of chlorogenic acid

Chlorogenic acid and its two structural components, quinic acid and caffeic acid, were pyrolyzed under reaction conditions simulating the typical pyrolysis conditions inside a burning cigarette. Major phenolic products from pyrolysis of the three acids were quantified and compared to evaluate the respective contribution of the quinic and caffeic acid moieties to the overall phenolic yield in chlorogenic acid pyrolysis. The results show that the most prominent phenolic product of chlorogenic acid is catechol, followed in order by phenol, hydroquinone, and alkylcatechols. Among these phenolics, catechol and alkylcatechols are formed mainly from the caffeic acid moiety of chlorogenic acid, while phenol and hydroquinone are produced predominantly from the quinic acid moiety. The quinic acid moiety can thus contribute more than 40 % of the overall phenolic yields in chlorogenic acid pyrolysis (0.54 mol mol^?1 chlorogenic acid pyrolyzed at 600 °C). Because considerable amounts of free quinic acid and its derivatives exist in tobacco, the results of this study indicate that quinic acid can be an important source of phenolic compounds, especially hydroquinone and phenol, in tobacco smoke.     

漆酶催化邻苯二酚开环的自由基反应机制

Enzyme-catalyzed reactions are a prominent field of research in green chemistry. Laccase is a multicopper oxidase, which we used to study the oxidation of catechol. A mechanism for this ring-opening reaction is also proposed. A o-benzosemiquinone radical was the initial nascent product of catechol oxidation during the catalytic reaction. This radical underwent two reaction pathways:(1) formation of an intramolecular adduct, which gave a carbon-centered furan-derived radical trapped by 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO); (2) formation of an intermolecular adduct producing dimeric and trimeric oligomers, as resolved by mass spectrometry. Products of the furan-like intermediate were also characterized by ¹H-NMR. Simultaneously, a hydroxyl radical (·OH) originating from the water solvent was identified by ¹⁷O-isotope tracing. The kinetics of this radical were also evident with substrates including 3-and 4-methyl catechol, but not with resorcinol and hydroquinone isomers, 3-and 4-nitro catechol, and 2, 3-dihydroxynaphthalene. The mechanism of selective activation and ring-opening at the C₄-C₅ site is discussed. This reaction is distinct from intra-and extra-diol ringcleavages catalyzed by catechol dioxygenase. These results are meaningful for mimicking laccase catalysis to further protein design.     

pMB/MWNTs/GC电极对水体中苯二酚异构体的同时测定

通过在多壁碳纳米管修饰玻碳电极上电聚合亚甲基蓝,制备了聚亚甲基蓝/碳纳米管/玻碳电极(pMB/MWNTs/GC)。用循环伏安法研究了3种苯二酚异构体在该电极上的电化学行为,结果表明,在pH7.0的磷酸盐缓冲溶液中,该修饰电极对苯二酚异构体的氧化表现出优异的电催化性能和选择性,对苯二酚、邻苯二酚和间苯二酚的氧化峰分别为0.104、0.203、0.609 V(vs.SCE),峰电位差值分别为99、406 mV。基于苯二酚异构体在pMB/MWNTs/GC修饰电极上的伏安行为,建立了苯二酚3种异构体同时分析的新方法。考察了各影响因素对测定的影响,最优实验条件下,在5.0×10-6~1.5×10-4mol.L-1范围内,3种苯二酚异构体的阳极峰电流与其浓度存在线性关系,检出限均为1.0×10-6mol.L-1。将该法用于水体及冲洗废液中苯二酚异构体含量的测定,结果满意。     

Synchronous fluorescence for simultaneous determination of hydroquinone and resorcinol in air samples

Several phenolic compounds are present in tobacco smoke. They are formed from the pyrolysis of tobacco during the smoking process and all of them are toxic. Therefore, the determination of these compounds in air samples is important. A rapid, simple, and sensitive method using a synchronous spectrofluorimetry technique was developed to quantify hydroquinone and resorcinol simultaneously. One of the advantages of this method is the simple and rapid sampling technique, which uses water as the absorption solution of the analytes in the air sample. The precision of the method (%RSD) was 1.8% and the detection limits were 0.125 mg m^–3 and 0.292 mg m^–3 for hydroquinone and resorcinol, respectively.     

漆酶活化碱木质素的磺甲基化反应活性研究

采用漆酶对碱木质素进行活化预处理,并对活化碱木质素进行磺甲基化改性,揭示了漆酶活化对碱木质素磺甲基化反应活性影响的作用机理.采用顶空气相色谱、红外光谱、凝胶渗透色谱、核磁共振等研究了漆酶活化碱木质素的结构特征,结果表明,漆酶对碱木质素既有聚合作用又有解聚作用,分子量变化不大,多分散性增加;漆酶活化使得碱木质素发生脱甲基作用,酚羟基含量增大,紫丁香基含量减低;另外,漆酶可氧化酚羟基变成苯氧自由基使碱木质素聚合.采用分子模拟对漆酶活化碱木质素的电子云密度进行了计算,结果表明脱甲基作用增大了木质素苯环上的电子云密度,有利于磺甲基化反应的进行.采用电位滴定测试磺甲基化产物的磺化度来表征其反应活性的大小,结果表明漆酶活化磺甲基化碱木质素的磺化度提高了35%,且对二氧化钛悬浮体系的分散性能得到明显提高.