Enhancement of the reaction between pulp components and hydroxyl radical produced by the decomposition of hydrogen peroxide under alkaline conditions

Experiments on alkaline hydrogen peroxide treatments with stepwise addition and oxygen pressurization were performed to determine whether they enhance the reaction between pulp components and hydroxyl radicals produced by the decomposition of hydrogen peroxide. In this study the degradation of methyl-dglucopyranoside (MGP), a model compound of pulp components, was an indicator of the progression of the reaction between pulp components and hydroxyl radicals. When comparing the degradation of MGP in the stepwise and one-time addition systems, MGP was degraded more in the stepwise addition system than in the one-time addition system when Fe³⁺ was added. This result indicates that the hydroxyl radical produced by the decomposition of hydrogen peroxide efficiently attacks MGP in the stepwise addition system. MGP was degraded to the same degree in the stepwise addition system as in the one-time addition system when Fe²⁺ or Mn²⁺ was added. Aggregation and precipitation of metal ions might affect their catalysis. Oxygen-pressurized hydrogen peroxide treatment caused almost no enhancement of the degradation of MGP compared to the treatment under atmospheric pressure. Instead, high stability of hydrogen peroxide was produced by oxygen-pressurized hydrogen peroxide treatment. Such high stability can result in frequent attacks of the hydroperoxide anion, the conjugate base of hydrogen peroxide, against some chromophores and quinones.Part of this paper was presented at the 1998 International Pulp Bleaching Conference, Helsinki, Finland     

银杏黄酮对活性氧自由基和过氧化氢清除作用的研究

研究了银杏叶中黄酮类提取物对超氧阴离子自由基、羟自由基清除率和过氧化氢的清除作用。为了进一步分析黄酮类在细胞内的清除作用,在反应体系中加入了大肠杆菌提取物以部分模拟细胞环境。结果表明黄酮类提取物对2类自由基和过氧化氢有明显的清除作用。同时发现在清除过程中,黄酮类与内酯类的相互作用比较复杂。但可以肯定的是大肠杆菌提取物的生物大分子对自由基和过氧化氢的清除没有影响或影响较小。     

Antioxidative activity of 6a-hydroxypterocarpan from the root of Sophora chrysophylla

The antioxidative activity of 6a-hydroxypterocarpan isolated from the root of Sophora chrysophylla has been investigated in vitro on lipid peroxidation by interaction of heamoglobin and hydrogen peroxide.     

Effects of hydrogen peroxide treatment on the surface properties and adhesion of ma bamboo (Dendrocalamus latiflorus)

The poor adhesion of bamboo coatings is a serious issue in the bamboo industry. To develop a pretreatment method that improves the adhesion of films and increases the economic value of bamboo products, a study of hydrogen peroxide treatment with solutions of various pH (pH 4–9) on bamboo surfaces was conducted. Five-year-old ma bamboo (Dendrocalamus latiflorus Munro), and nitrocellulose lacquer were used in the study. Surface properties of the bamboo such as contact angle and color were evaluated, and 180° peel strength and shear strength tests for measuring adhesion of films were conducted. The results showed that the wettability of water droplets and the carbonyl group concentration on the bamboo surface were increased significantly by alkaline (pH 8 and 9) hydrogen peroxide treatments. There was only minor color variation and the outer wax layer of bamboo was etched to form additional recesses after hydrogen peroxide treatment. It was also found that all hydrogen peroxide treatments improved the adhesion of bamboo coating; bamboo treated with hydrogen peroxide at pH 7 showed the greatest improvement. The enhanced adhesion was attributed to the mechanical interlocking of the film on the treated bamboo rather than to surface activation.     

Polyethylene degradation by manganese peroxidase in the absence of hydrogen peroxide

A possible role of Tween 80 in the polyethylene degradation by manganese peroxidase (MnP) and the basis of the MnP action in the absence of hydrogen peroxide were investigated. The MnP activity in the system was retained its maximum level for 6 days in the presence of Tween 80. Tween 20 and CHAPSO stabilized MnP in the system similarly to Tween 80, and these surfactants also promote the polyethylene degradation. The system containing malonate buffer, Mn(II), and MnP produced Mn(III) in the absence of hydrogen peroxide, but the effect of Tween 80 addition on Mn(III) production in the absence of hydrogen peroxide was small. The results show that Mn(III) is generated by the MnP action initiated and amplified by the decomposition of malonate by Mn(III) and that a surfactant such as Tween 80 is required to stabilize MnP in the system.This study was presented in part at the 42nd lignin symposium, Sapporo, October 1997 and the 43rd lignin symposium, Fuchu, Tokyo, October 1998     

Cytoprotective activities of hydroxycinnamic acid amides of serotonin against oxidative stress-induced damage in HepG2 and HaCaT cells

Hydroxycinnamic acid amides of serotonin (HCAAS) [caffeoylserotonin (compound 1), p-coumaroylserotonin (compound 2), and feruloylserotonin (compound 3)] are secondary metabolites produced in plants. The aim of this study was to investigate the cytoprotective effects of HCAAS based on intracellular reactive oxygen radical (ROS) generation, lipid peroxidation, protein carbonylation, and phosphorylation of histone H2AX in H₂O₂ treated-HepG2 and HaCaT cells. We have shown that HCAAS showed various strong antioxidant activities in hydrogen peroxide treated both cell lines, suggesting that these compounds may play as chemotherapeutic agents for preventing or reducing the oxidative stress-induced diseases.     

Use of hemicellulase in sequence with hydrogen peroxide and laccase for improvement of teak veneer surface color

Teak veneer was treated with a commercial hemicellulase from Thermomyces lanuginosus in sequence with hydrogen peroxide or a hydrogen peroxide-laccase mixture to improve the veneer surface color and at the same time to reduce the necessary amount of hydrogen peroxide. The removal of a small portion of hemicellulose from the teak veneer surface could be carried out after treatment with the hemicellulase preparation as 0.05 xylanase unit/ml for 30 min. The veneer samples immediately after the hemicellulase treatment were subjected to the designated concentration of hydrogen peroxide or hydrogen peroxide-laccase mixture at 60°C at pH 6.5 for 4 h. The changes in veneer color were measured by using imaging technology as percentage change in gray scale. A treatment combination of hemicellulase containing xylanase, hydrogen peroxide, and laccase yielded a color improvement close to that achieved using 20% hydrogen peroxide. The results showed that hemicellulase pretreatment could improve the bleachability of teak veneer surfaces treated with hydrogen peroxide or hydrogen peroxide-laccase mixture.     

Extractives of <Emphasis Type="Italic">Quercus crispula</Emphasis> sapwood infected by the pathogenic fungi <Emphasis Type="Italic">Raffaelea quercivora</Emphasis> I: comparison of sapwood extractives from noninfected and infected samples

The extracts of Quercus crispula infected by the ambrosia fungus, Raffaelea quercivora, were investigated. Phenol and tannin analyses indicated that normal sapwood (NS) contained a considerable amount of hydrolysable tannins, while infected colored sapwood (IS) contained less hydrolysable tannins and more phenols than NS. In treating pentagalloyl glucose (PGG), which is a model compound of hydrolysable tannins, with a culture medium of R. quercivora, PGG was rapidly hydrolyzed to produce gallic acid. The resulting gallic acid decreased in concentration over the subsequent cultivation period eventually disappeared. Measuring tannase and laccase activities of the culture medium of R. quercivora, tannase activity increased gradually from the beginning, while laccase activity increased rapidly at 5 days of incubation and disappeared at 8 days. An oxidative product from gallic acid treated with laccase was isolated by preparative high performance liquid chromatography, and was identified as purprogallincarboxylic acid (PGCA) by nuclear magnetic resonance spectroscopy and electron-impact mass spectrometry. PGCA was present in a 70% aqueous acetone extract of IS, and showed slight growth inhibition against R. quercivora. Part of this study was presented at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, Japan, 2007     

Glyoxal oxidase supplies hydrogen peroxide at hyphal tips and on hyphal wall to manganese peroxidase of white-rot fungus Phanerochaete crassa WD1694

Peroxidase activity staining localized at hyphal tips of white-rot fungus Phanerochaete crassa WD1694 that was cultivated in a shaken liquid culture containing unbleached kraft pulp was investigated. Manganese peroxidase was detected in culture solution, washing solution of mycelium, and mycelial extract. Glyoxal oxidase was detected only in mycelial extract and was not detected in culture solution. Addition of hydrogen peroxide generated peroxidase activity staining in the culture solution. Addition of catalase resulted in no staining in the culture of P. crassa WD1694, and the addition of methylglyoxal resulted in marked peroxidase activity staining at hyphal tips and on hyphal wall. In an optimized culture, glyoxal oxidase was produced in culture solution. Although the production of glyoxal oxidase and manganese peroxidase had a positive correlation, the secretion and the peak of glyoxal oxidase was observed 3 and 2 days later than those of manganese peroxidase. The N-terminal sequence of purified glyoxal oxidase had very high homology with that of P. chrysosporium. These results elucidated the hydrogen peroxide supply system in lignin biodegradation by white-rot fungi, i.e., while remaining on the hyphal cell wall, glyoxal oxidase provides hydrogen peroxide to manganese peroxidase that had diffused into the culture solution beforehand.     

银杏黄酮对活性氧自由基和过氧化氢清除作用的研究

采用在反应体系中加入大肠杆菌提取物来部分模拟细胞环境,进一步分析银杏叶中黄酮类提取物在细胞内对超氧阴离子自由基、羟自由基清除率和过氧化氢的清除作用.结果表明,黄酮类提取物对两类自由基和过氧化氢有明显的清除作用,但在清除过程中黄酮类与内酯类的相互作用比较复杂.大肠杆菌提取物的生物大分子对自由基和过氧化氢的清除影响较小或没有影响.     

外源褪黑素对番茄灰霉病抗性及抗氧化酶系统的影响

指出了对于番茄灰霉病目前缺乏有效的控制手段,采用生物或非生物诱导子控制病害是一种有前途的方式,采用100μmol的褪黑素外源施用后接种灰霉菌,接种5d后计算了病情指数,实验结果显示:番茄外施褪黑素可降低病情指数,提高番茄的抗性;外源褪黑素处理通过在一定范围内提高超氧阴离子产生速率和过氧化氢的含量,抗氧化系统也随之升高,SOD的活性在整个处理过程中显著高于对照,这些结果说明褪黑素可诱导ROS爆发,刺激细胞进入敏化状态,SOD和CAT有效控制过高浓度的ROS含量。     

Programmed cell death of Ulmus pumila L. seeds during aging

The programmed cell death (PCD) characteristics of Ulmus pumila L. seeds were investigated. The seeds were treated at a high temperature of 37°C and 100% relative humidity for six days. DAPI (4′6-diamidino-2-phenylindole) staining revealed that the aging treatment induced condensation and margination of chromatin, as well as the formation of apoptotic bodies. DNA electrophoresis results of U. pumila seeds on an agarose gel showed a characteristic “ladder” pattern. Levels of electrolyte leakage of seed cells showed that membranes retained their integral form during almost the entire aging time. There was an immediate increase in the production rate of superoxide anion (O₂ ⁻) and in the amount of hydrogen peroxide (H₂O₂), which remained at a μmol level. All of these common characteristics indicate that seed aging can be classified as PCD. __________ Translated from Journal of Beijing Forestry University, 2007, 29(3): 8–14 [译自: 北京林业大学学报]     

The use of diffuse-reflectance laser-flash photolysis to study the photochemistry of the kraft pulp treated with hydrogen peroxide under alkaline and acidic conditions

 The diffuse-reflectance laser-flash photolysis method together with ground state diffuse reflectance spectroscopy have been used to study the effect of pH and temperature of the hydrogen peroxide treatment on oxygen delignified softwood kraft pulp. Received 20 December 1999     

毛竹水解渣木质素氢解制备芳香化学品

以毛竹水解渣为原料,分别采用过氧化氢法和甲醇法提取木质素,在相同的反应条件下对比了两种木质素转化及产物分布的结果,并进一步优化了过氧化氢法提取的木质素的氢解转化最优条件.研究结果表明:温度为220℃,反应时间60 min时,过氧化氢木质素可以全部转化为可溶物,单体收率为14.85％;甲醇法提取的甲醇木质素,转化产物中可...     

THE QUICK DETERMINATION METHOD OF RESIN CONTENT IN LARCH WOOD

The resin content in larch wood is usually determined by the traditionalBenzene-Alcohol Extract Method(BAEM).In order to meet the requirement of production prac-tice,the authors present two simple quick determination methods,IR lamp method and hydrogenperoxide solution method.Compared with the results of traditional method,the results of newmethods are nearly the same as former,therefore,both two methods can reflect the change condi-tion of resin content in wood.     

双氧水和固化剂对稻草碎料板性能影响的比较

分析比较用双氧水处理稻草、板材表芯层固化剂的添加量对稻草碎料板性能影响的结果表明,用浓度为10%、pH值为10~11的双氧水处理稻草,会降低稻草板的综合性能;而将稻草板的表芯层分开添加不同量的固化剂,压制的稻草板可达到国标要求。     

Evaluation of Pinus radiata seed treatments to control Fusarium circinatum: effects on seed emergence and disease incidence

In this study, the effects of hot water (HWT), hydrogen peroxide and fungicides on the incidence of Fusarium circinatum on artificially inoculated Pinus radiata seeds were evaluated. Fifteen commercial fungicide formulations were screened in vitro for inhibitory activity on mycelial growth and conidial germination of F. circinatum. With half‐maximal effective concentration (EC₅₀) lower than 0.5 ppm, fluazinam, imazalil and tebuconazole were the most effective fungicides on mycelial growth, while captan, mancozeb or pyraclostrobin were the most effective (EC₅₀ < 0.3 ppm) on conidial germination. Based on the results obtained, imazalil, fluazinam, mancozeb and pyraclostrobin were selected for further testing. The effects of HWT, hydrogen peroxide and fungicide treatments on seed emergence and the incidence of F. circinatum were assessed. Seed treatments with fungicides prior to sowing were less effective and inconsistent in reducing the incidence of F. circinatum on seedlings. In contrast, hot water and hydrogen peroxide treatments significantly reduced F. circinatum contamination on P. radiata seeds with an overall disease incidence lower than 0.8% on seedlings. Furthermore, subsequent application of fungicides on seedlings did not improve the effectiveness of HWT. These results, therefore, suggest that hot water is a better alternative to hydrogen peroxide and fungicides as Pinus seed treatment against F. circinatum and could easily be implemented as standard in commercial nurseries to control the spread of the pitch canker disease.     

新疆杨扦插育苗促进生根率技术研究

通过使用高锰酸钾、醋酸、双氧水等3种氧化剂和吲哚乙酸、吲哚丁酸、萘乙酸等3种外源激素不同浓度对新疆杨插穗进行处理,以探讨新疆杨扦插生根促进技术。结果表明:虽然不同氧化剂试验处理对新疆杨生根率与对照相比差异是显著的,但没有达到生产上对生根率的要求;不同的激素浓度水平会明显影响新疆杨的生根率,以吲哚丁酸浸泡插穗6h最佳浓度是200mg·L-1,扦插生根效果较好,生根率达到3.65%。     

DMD的活化预处理及其全无氯漂序的研究

研究了桉木硫酸盐浆对氧脱木质素段和过氧化氢漂段的活化作用以及ＤＭＤ用量对氧段和过氧化氢段浆性能的影响,使经ＭＯＱＭＰ多段漂白的纸浆最终白度达８０％以上,纸浆粘度满足要求,可以实现桉木硫酸盐浆的全无氯漂白。     

木聚糖酶预处理对麦草化学机械浆可漂性及白度的改善

探讨了以玉米芯片为碳源制备木聚糖酶及麦草化学机械浆经该木聚糖酶预处理后可漂性和白度的改善效果。结果表明，直接以玉米芯为底物、里氏木霉为菌种产酶效果较好，当底物浓度为18g/L时，木聚糖酶活力可达38．34IU／mL。木聚糖酶预处理有利于改善麦草化机浆的可漂性，促进其过氧化氢漂白，有提高漂白浆白度，降低漂剂消耗。研究表明，当经单段H2O2漂至相同白度时，木聚糖酶预处理后可节约50％的H2O2用量。若麦草CMP酶处理后采用高浓度两段过氧化氢漂白，即XP3P3漂序（H2O2总量为6％0时，白度可达60％（ISO）以上。