Examination of Antioxidative System's Responses in the Different Phases of Drought Stress and During Recovery in Desert Plant Reaumuria soongorica (Pall.) Maxim

The aim of this study was to test the protective roles of superoxide dismutases (SODs), guaiacol peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) against oxidative damage and their activities in different phases of the dry down process in Reaumuria soongorica (Pall.) Maxim. leaves. Drought stress was imposed during 100 consecutive days and rewatering after 16, 72, and 100 days. The concentration of hydrogen peroxide (H2O2), malondialdehyde, and SODs activities were elevated significantly with progressing drought stress. POD and CAT activities increased markedly in the early phase of drought and decreased significantly with further drought stress continuation, and POD activity was unable to recover after rewatering. Ascorbate, reduced glutathione, APX, and GR activities declined in the initial stages of drought process, elevated significantly with further increasing water deficit progression and recovered after rewatering. These results indicate that: (1) iron SODs-removing superoxide anion is very effective during the whole drought stress; (2) CAT scavenges H2O2 in the early phase of drought and enzymes of ascorbate-glutathione cycle scavenge H2O2 in further increasing drought stress; and (3) POD does not contribute to protect against oxidative damage caused by H2O2 under drought stress.

The influence of the cation of quaternized chitosans on antioxidant activity

Various quaternized chitosans (QCSs) were synthesized according to previous method. Their reducing power and antioxidant potency against hydroxyl radicals ((OH)-O-center dot) and hydrogen peroxide (H2O2) were explored by the established systems in vitro. The QCSs exhibited markedly antioxidant activity, especially TCEDMCS, whose IC50 on hydroxyl radicals was 0.235 mg/mL. They showed 65-80% scavenging effect on hydrogen peroxide at a dose of 0.5 mg/mL. Generally, the antioxidant activity decreased in the order TCEDMCS > TBEDMCS > EDMCS > PDMCS > IBDMCS > Chitosan. Furthermore, the order of their (OH)-O-center dot and H2O2 scavenging activity was consistent with the electronegativity of different substituted groups in the QCSs. The QCSs showed much stronger antioxidant activity than that of chitosan may be due to the positive charge density of the nitrogen atoms in QCSs strengthened by the substituted groups. (C) 2009 Elsevier Ltd. All rights reserved.

Molecular cloning and characterization of a catalase gene from Zhikong scallop Chlamys farreri

Catalase is one of the central enzymes involved in scavenging the high level of reactive oxygen species (ROS) by degradation of hydrogen peroxide to oxygen and water. The full-length catalase cDNA of Zhikong scallop Chlamys farreri (denoted as CfCAT) was identified from hemocytes by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) approaches. The nucleotide sequence of CfCAT cDNA consisted of 3146 bp with a 5' UTR of 103 bp, an unusually long 31 UTR of 1519 bp with a canonical polyadenylation signal sequence AATAAA and a potyA tail, and an open reading frame (ORF) of 1521 bp encoding a polypeptide of 507 amino acids with predicted molecular weight of 57.5 kDa. The deduced amino acid sequence of CfCAT has significant homology to catalases from animals, plants and bacteria. Several highly conserved motifs including the proximal heme-ligand signature sequence RLFSYNDTH, the proximal active site signature FNRERIPERVVHAKGGGA, and the three catalytic amino acid residues of His(72), Asn(145) and Tyr(355) were identified in the deduced amino acid sequence of CfCAT. The CfCAT was demonstrated to be a peroxisomal glycoprotein with two potential glycosylation sites and a peroxisome targeting signal of ANL that was consistent with human, mouse and rat catalases. The time-course expression of CfCAT in hemocytes was measured by quantitative real-time PCR. The expression of CfCAT increased gradually and reached the highest point at 12 h post-Vibrio infection, then recovered to the original level at 24 h. All these results indicate that CfCAT, a constitutive and inducible protein, is a member of the catalase family and is involved in the process against ROS in scallop. (c) 2007 Published by Elsevier Ltd.

cDNA cloning, characterization and expression analysis of the antioxidant enzyme gene, catalase, of Chinese shrimp Fenneropenaeus chinensis

Catalase is an important antioxidant protein that protects organisms against various oxidative stresses by eliminating hydrogen peroxide. The full-length catalase cDNA of Chinese shrimp Fenneropenaeus chinensis was cloned from the hepatopancreas using degenerate primers by the method of 3' and 5' rapid amplification of cDNA ends PCR. The cDNA sequence consists of 1892 bp with a 1560 bp open reading frame, encoding 520 amino acids with high identity to invertebrate, vertebrate and even bacterial catalases. The sequence includes the catalytic residues His71, Asn144, and Tyr354. The molecular mass of the predicted protein is 58824.04 Da with an estimated pl of 6.63. Sequence comparison showed that the deduced amino acid sequence of F. chinensis catalase shares 96%, 73%, 71% and 70% identity with that of Pacific white shrimp Litopenaeus vannamei, Abalone Haliotis discus hannai, Zhikong scallop Chlamys farreri and Human Homo sapiens, respectively. Catalase transcripts were detected in hepatopancreas, hemocytes, lymphoid organ, intestine, ovary, muscle and gill. by real-time PCR. The variation of catalase mRNA transcripts in hemocytes and hepatopancreas was also quantified by real-time PCR and the result indicated that the catalase showed up-regulated expression trends in hemocytes at 14 h and in hepatopancreas at 37 h after injection with white spot syndrome virus (WSSV). (c) 2008 Elsevier Ltd. All rights reserved.

Identification and molecular analysis of a stress-inducible Hsp70 from Sciaenops ocellatus

Hsp70 proteins are a family of molecular chaperones that are involved in many aspects of protein homeostasis. In this study, an Hsp70 homologue (SoHsp70) was identified from red drum Sciaenops ocellatus and analyzed at molecular level. The open reading frame of SoHsp70 is 1920 bp and intronless, with a 5'-untranslated region (UTR) of 399 bp and a 3'-UTR of 241 bp. The deduced amino acid sequence of SoHsp70 shares 84-92% overall identities with the Hsp70s of a number of fish species. In silico analysis identified in SoHsp70 three conserved Hsp70 domains involved in nucleotide and substrate binding. The coding sequence of SoHsp70 was subcloned into Escherichia coli, from which recombinant SoHsp70 was purified and, upon ATPase assay, found to exhibit apparent ATPase activity. Expressional analysis showed that constitutive expression of SoHsp70 was detectable in heart, liver, spleen, kidney, brain, blood, and gill. Experimental challenges with poly(I:C) and bacterial pathogens of Gram-positive and Gram-negative nature induced SoHsp70 expression in kidney to different levels. Stress-responsive analysis of SoHsp70 expression in primary cultures of red drum hepatocytes showed that acute heat shock treatment elicited a rapid induction of SoHsp70 expression which appeared after 10 min and 30 min of treatment. Exposure of hepatocytes separately to iron, copper, mercury, and hydrogen peroxide significantly unregulated SoHsp70 expression in time-dependent manners. Vaccination of red drum with a Streptococcus iniae bacterin was also found to induce SoHsp70 expression. Furthermore, recombinant SoHsp70 enhanced the immunoprotective effect of a subunit vaccine. Taken together, these results suggest that SoHsp70 is a stress-inducible protein that is likely to play a role in immunity and in coping with environmental and biological stresses. (C) 2010 Elsevier Ltd. All rights reserved.

羟基自由基降解琼胶及其产物的活性研究

琼胶是一种从石花菜等红藻中提取的，目前生产工艺和结构等方面研究比较成熟的海藻多糖，广泛应用于医药、仪器等行业。但是，海藻多糖因为具有分子量大，粘度大，溶解度较小的等特点，而使其应用范围受到限制。利用降解的手段对其进行修饰，降低分子量和粘度，改善溶解性，可以拓展其应用范围。并且根据文献报道，琼 胶寡糖具有一些特殊的生物活性，如抗氧化性，抗炎症等。因此，对琼胶降解的研究具有生要意义。本研究中，为了选择一种合适的降解方法，进行了几种水解方法的尝试，其中包括在不同湿度和酸度下盐酸水解，过氧化氢和醋酸催化水解，Fenton体系羟基自由基降解。对于酸水解和Fenton体系氧化还原降解方法，通过粘度法对反应的速度进行了比较，表明氧化还原降解反应中琼胶的粘度降低比较快，并且具有代表性和新意，确定为本实验的降解琼胶的方法并对氧化还原降解所得的产物进行了活性实验。通过模仿自然界普遍存在的氧化还原降解反应，利用Vc诱导的Fenton体系产生的羟基自由基氧化还原降解琼胶得到低分子量的琼胶。降解产物经过高速离心、60％乙醇沉淀，除去分子量比较大的降解产物和磷酸盐，得到可溶于60％乙醇的分子量估计小于3000的降争产物，其产率为85％。利用经Sephadex-G25凝胶色谱分离所香的不同分子量的级分进行分子量和α－葡萄糖苷酶抑制活性关系的实验。降解产物对α－葡萄糖苷酶的抑制率和各级分的浓度呈线性正相关，并且各级分的IC_(50)则随着分子量的降低而降低。另外，对所得的降解产物混合物进行了红外吸收光谱、质子去偶核磁共震碳谱和负离子基质辅助激光诱导－飞行时间质谱结构分析。结果表明，氧化还原降解反应的专一性差，在得到寡糖的同时，在光谱图中出现一些比较复杂的副产物的结构信息。最后，根据MTT法的原理，以有体皮肤成纤维细胞为材料，通过紫外线辐射产生自由基造成氧化损伤，研究降解产物对成纤维细胞的保护作用。当无紫外线辐射时，降解产物对成纤维细胞具有显著的促进生长增殖作用：当经UVa、UBb辐射时则可以显著地表现出对损伤的保护作用，并且这种促进生长和保护作用呈显著的量效关系，表明降解产物具有清除基自由基的作用。但是，因为氧化还原降解以应的机理尚不十分明的以及琼羟胶的特殊结构，使得反应的副产物很难预测，也就使得分离工作难以进行，所以，根据目前所得的信息，尚不能确定是降解产物的什么级分产生的以上两种生物活性。

Antioxidant activity and cytoprotective effect of kappa-carrageenan oligosaccharides and their different derivatives

Antioxidant activity of kappa-carrageenan oligosaccharides (OM) and their chemical modification derivatives was investigated employing various established in vitro systems, such as reducing power, iron ion chelation, and total antioxidant activity using beta-carotene-linoleic acid system. The oversulfated (SD), lowly (LAD), and highly acetylated derivatives (HAD) in reducing power assay, the phosphorylated derivative (PD) in metal chelating assay, and oversulfated and phosphorylated derivatives in total antioxidant activity assay exhibited antioxidant activity higher than that of carrageenan oligosaccharides. The results indicated that the chemical modification of carrageenan oligosaccharides can enhance their antioxidant activity in vitro. The protective effects of the carrageenan oligosaccharides and their chemically modified derivatives against H2O2 and UVA (long-wave ultraviolet radiation) induced oxidative damage on rat thymic lymphocyte were investigated by measuring cell viability via 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT). Thymic lymphocyte exposure to H2O2 and UVA, a marked reduction in cell survival was observed, which was significantly prevented by carrageenan oligosaccharides and their derivatives (preincubated for 2 h) at 66.7-2000 mu g/mL. But both the carrageenan oligosaccharides and their different derivatives showed the similar protective effects on intracellular level. Taken together, these results suggest that carrageenan oligosaccharides and their derivatives show relevant antioxidant activity both in vitro and in a cell system. (C) 2005 Elsevier Ltd. All rights reserved.

Degradation of porphyran from Porphyra haitanensis and the antioxidant activities of the degraded porphyrans with different molecular weight

In the present paper, ascorbate and hydrogen peroxide (H2O2) were used to degrade porphyran. It was found that porphyran could be degraded by free radical that was generated by ascorbate and H2O2 in combination. It was possible to prepare desired porphyran products with different molecular weight by adjusting ascorbate to H,02 proportions and their concentrations. The molar ratio of I was demonstrated more effective than in other ratios. Higher concentrations accelerated the degradation. Moreover, results of chemical analysis and FT-IR spectra suggested that the main structure of degraded products still remained although some changes happened. The degraded and natural porphyrans possessed scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical activity and reducing power. Higher antioxidant activities were found in both systems when the molecular weight was reduced. The results indicated that the antioxidant activities were closely related to the molecular weight. The degraded porphyrans are potential antioxidant in vitro. (c) 2006 Elsevier B.V. All rights reserved.

Preparation of Dendritic Copper Nanostructures and Their Characterization for Electroreduction

Dendritic copper nanostructures of different morphologies were synthesized by a surfactant-free electrochemical method. Single crystal nature of the nanostructures was revealed from their X-ray diffraction and electron diffraction patterns. Mechanism of dendrite formation was discussed from thermodynamic aspects using the concept of supersaturation. Supersaturation of the copper metal reduced on the surface of the electrode was the crucial factor for the generation of different morphologies. Effects of applied potential, temperature, and the solution concentration on the supersaturation were studied. The NO3- and H2O2 electroreduction ability of the dendritic materials was tested. Use of copper dendrite-modified electrode as NO3- sensor was demonstrated.

Electrochemical impedance spectroscopy analysis for oxygen reduction reaction in 3.5% NaCl solution

The electrochemical impedance spectroscopy (EIS) at different potentials has been used to study the oxygen reduction reaction (ORR) in 3.5% NaCl solution on glassy carbon (GC) electrode in this work. Results show that ORR consists of three two-electron reaction steps and both superoxide ion (O-2(-)) and hydrogen peroxide (H2O2), which are produced by ORR, obstruct the diffusion of oxygen to the surface of the electrode and make the EIS results change into a transmissive finite diffusion process with the real part contraction and a reflective finite diffusion process from a semi-infinite diffusion process. The values of electron transfer resistance (R-t) and diffusion resistance (R-d) were calculated from EIS. O-2(-) influenced strongly on the Rt values and induced a maximum at -0.45 V.

Simultaneous and ultrarapid determination of reactive oxygen species and reduced glutathione in apoptotic leukemia cells by microchip electrophoresis

A microchip electrophoresis method coupled with laser-induced fluorescence (LIF) detection was established for simultaneous determination of two kinds of intracellular signaling molecules (reactive oxygen species, ROS, and reduced glutathione, GSH) related to apoptosis and oxidative stress. As the probe dihydrorhodamine-123 (DHR123) can be converted intracellularly by ROS to the fluorescent rhodamine-123 (Rh123), and the probe naphthalene-2,3-dicarboxaldehyde (NDA) can react quickly with GSH to produce a fluorescent adduct, rapid determination of Rh-123 and GSH was achieved on a glass microchip within 27 s using a 20 mm borate buffer (pH 9.2). The established method was tested to measure the intracellular ROS and GSH levels in acute promyelocytic leukemia (APL)-derived NB4 cells. An elevation of intracellular ROS and depletion of GSH were observed in apoptotic N134 cells induced by arsenic trioxide (AS(2)O(3)) at low concentration (1-2 mu m). Buthionine sulfoximine (BSO), in combination with AS(2)O(3) enhanced the decrease of reduced GSH to a great extent. The combined treatment of AS(2)O(3) and hydrogen peroxide (H2O2) led to an inverse relationship between the concentrations of ROS and GSH obtained, showing the proposed method can readily evaluate the generation of ROS, which occurs simultaneously with the consumption of the inherent antioxidant.

Structural relation properties of hydrothermally stable functionalized mesoporous organosilicas and catalysis

The surfactant assistant syntheses of sulfonic acid functionalized periodic mesoporous organosilicas with large pores are reported. A one-step condensation of tetramethoxysilane (TMOS) with 1,2-bis(trimethoxysilyi)ethane (BTME) and 3-mercaptopropyltrimethoxysilane (MPTMS) in highly acidic medium was performed in the presence of triblock copolymer Pluronic P123 and inorganic salt as additive. During the condensation process, thiol (-SH) group was in situ oxidized to sulfonic acid (-SO3H) by hydrogen peroxide (30 wt % H2O2). X-ray diffraction studies along with nitrogen and water sorption analyses reveal the formation of stable, highly hydrophobic, and well-ordered hexagonal mesoscopic structures in a wide range of -CH2CH2-concentrations in the mesoporous framework. The resultant materials were also investigated by Si-29 MAS and C-13 CP MAS NMR, thermogravimetric analyses, UV-Raman spectroscopy, and FT-IR spectroscopy. The role of the bridged organic group on the hydrothermal stability of the mesoporous materials was established, which revealed an enhancement in hydrothermal stability of the materials with incorporation of the bridged organic groups in the network. The catalytic performance of -SO3H functionalized mesoporous materials was investigated in the esterification of ethanol with acetic acid, and the results demonstrate that the ethane groups incorporated in the mesoporous framework have a positive influence on the catalytic behavior of the materials.