Effects of Water─soluble Components Isolated from Salviamilltiorrhiza on Oxygen Free Radical Generation and LipidPeroxidation

The effects of water─soluble components isolated from Salvia miltiorrhiza on oxygen free radical prodction and lipid peroxidation were estimated. Five components(10 μmol/L)were shown to inhibit superoxide anion generation by xanthine─xanthine oxidase system. It was also demonstrated that six components( 100 μmol/L) prevented H_2O_2─induced hemolysis and MDA fonnation in mouse erythrocytes.The effects of Sal A, Sal B, Sal C and Ros A were dose dependent. In Langendorff rat heart, pretreatment with Sal A 20μmol/L significantly prevented MDA production induced by 30 min reoxygenation after 45 min anoxia.The results indicated that there were also other potent antioxidant componentts in Salvia milliorrhiza besides Dphl and Pal. The protection of Sal A against myocardial anoxiareoxygenation inury may be mainly ascribed to its oxygen free radical scavenging activity.

Antioxidant,lipid peroxidation inhibition and free radical scavenging efficacy of a diterpenoid compound sugiol isolated from Metasequoia glyptostroboides

Objective:To investigate the antioxidant enicacy of a biologically active dilerpenoid compound sugiol isolated from Metasequoia glyptostroboides(M.glyptostroboides)in various antioxidant models.Methods:An abietane type diterpenoid sugiol,isolated from ethyl acetate extract of M.glyptostroboides cones,was analyzed for its antioxidant efficacy as reducing power ability and lipid peroxidation inhibition as well as its ability to scavenge free radicals such as 1,1-diphenyl-2-picryl hydrazyl,nitric oxide,superoxide and hydroxyl radicals.Results:The sugiol showed significant and concentration-dependent antioxidant and free radical scavenging activities.Consequently,the sugiol exerted lipid peroxidation inhibitory effect by 76.3%as compared to a-tocopherol(80.13%)and butylaled hydroxyanisole(76.59%).In addition,the sugiol had significant scavenging activities of l,l-diphenyl-2-picryl hydrazyl,nitric oxide,superoxide and hydroxyl free radicals in a concentration-dependent manner by 78.83%,72.42%,72.99%and 85.04%,when compared to the standard compound ascorbic acid(81.69%,74.62%,73.00%and 73.79%)and a-tocopherol/butylated hydroxyanisole(84.09%,78.61%,74.45%and 70.02%),respectively.Conclusions:These findings justify the biological and traditional uses of M.glyptostroboides or its secondary metabolites as confirmed by its promising antioxidant efficacy.

Evaluation of lipid peroxidation inhibition and free radical scavenging abilities of 5,6,7-trimethoxy dihydroflavonols

Four naturally rare 5,6,7-trimethoxy-2,3-cis-dihydroflavonols （3-6） and two 5,6,7-trimethoxy-2,3-trans-dihydroflavonols （7-8） were designed and synthesized. Their antioxidative properties were evaluated by way of examining their scavenging capacities towards DPPH and O2^＊- free radicals, as well as by measuring their inhibitory ability against LPO. Both the 2,3-trans and the 2,3- cis conformers exhibited certain quenching abilities to DPPH and O2^＊- radicals, while most of the synthetic dihydroflavonols demonstrated remarkable inhibition to LPO.

Protective Effects of Tea Polyphenol on Cerebral Ischemia-Reperfusion Injury in Rats and Its Scavenging Oxy-radical and Anticerebral Lipid Peroxidation Effects

AIM To study the protective effects of tea polyphenol (TP) on cerebral ischemia reperfusion injury in rats and its scavenging oxygen free radical(OFR) activities and antilipid peroxidation in vitro . METHODS Cerebral ischemia reperfusion injury was produced by bilateral ligation of the common carotid arteries with vagus nerves and reperfusion for 45 min. The mitochondrial lipid peroxidation of rat brain induced by oxygen free radical was measured by thiobarbituric acid spectrophotometry. Superoxide anion (O 2) from xanthine xanthine oxidase system and hydroxyl radical (·OH) from Fe 2+ -H 2O 2 system were determined with spectrophotometry. RESULTS During Cerebral ischemia reperfusion,TP improved the activities of superoxide dismutase ( P 【0 05), GSH peroxidase( P 【0 01) and catalase( P 【0 01), while decreasing the maiondialdchyde content in the brain( P 【0 05) and brain water content ( P 【0 01). Tea polyphenol possessed significantly scavenging effects on ·OH produced by Fenton reaction and O 2 produced by xanthine xanthine oxidase system (the IC 50 were 2 2 mmol·L -1 and 1 9 mmol·L -1 respectively). Tea polyphenol could significant inhibit the lipid peroxidation of cerbral mitochondrial membrane induced by ·OH in a concentration dependent manner. CONCLUSION The results indicate that tea polyphenol could protect the injury on cerebral ischemia reperfusion in rats for OFR, these effects may be related to its scavenging effects on oxygen free radicals and antilipid peroxidant.

Mechanisms of Inhibitory Effects of Breviscapine on Lipid Peroxidation in Rat Brain Mitochondria

The mechanisms by which breviscapine (Bre) inhibits the lipid preoxidation in rat brain mitochondria were investigated. The mitochondrial lipid peroxidation of rat brain induced by oxygen free radical was measured by thiobarbituric acid spectrophotometry. The chelating activities of Bre for Fe 2+ were tested by differential spectrum. Superoxide anion (O 2)from xanthine xanthine oxidase (Xan XO) system and hydroxyl radical (·OH) from FeSO 4 H 2O 2 system were determined with spectrophotometry. It was found that Bre could effectively inhibit the lipid peroxidation of brain mitochondria induced by free radicals driven from Xan XO and FeSO 4 H 2O 2 system. The IC 50 of Bre were 93 01 μmol·L -1 for Xan XO system and 62 18 μmol·L -1 for FeSO 4 H 2O 2 system. Bre also scavenged O 2 and ·OH produced by Xan XO and FeSO 4 H 2O 2 systems. The IC 50 of Bre were 32 63 μmol·L -1 for O - 2 and 20 22 μmol·L -1 for ·OH. Furthermore, the chelating Fe 2+ activity of Bre was shown. It may be concluded that Bre inhibited lipid peroxidation at different stages of the reaction of oxygen free redial with the mitochondria membrane: (1) the formation of ·OH; (2) the initiation of the lipid peroxidation, by chelating Fe 2+ and scavenging O 2 as well as ·OH. The scavenging oxygen free radicals and chelating iron are the mechanisms of inhibitory effect of Bre on lipid peroxidation.

Mistletoe alkali inhibits peroxidation in rat liver and kidney

AIM： To explore the antioxidant and free radica scavenger properties of mistletoe alkali （MA）. METHODS： The antioxidant effect of mistletoe alkali on the oxidative stress induced by carbon tetrachloride （CCh） in rats was investigated. The rats were divided into four groups （n = 8）： CCh-treated group （1 mL/kg body weight）, MA -treated group （90 mg/kg）, CCh＋MA-treated group and normal control group. After 4 wk of treatment, the level of malondialdehyde （MDA）, a lipid peroxidation product （LPO） was measured in serum and homogenates of liver and kidney. Also, the level of glutathione （GSH）, and activities of glutathione reductase （GR）, glutathione peroxidase （GSPx）, superoxide dismutase （SOD）, and glutathione-S-transferase （GST） in liver and kidney were determined. Scavenging effects on hydroxyl free radicals produced in vitro by Fenton reaction were studied by ESR methods using 5,5-dimethyl-1-pyrroline-N-oxide （DMPO） as a spin trap reagent and H2O2/UV as the OH· source. Urinary 8-hydroxydeoxyguanosine （8-OHdG） was determined by competitive ELISA. RESULTS： In CCh-treated group, the level of LPO in serum of liver and kidney was significantly increased compared to controls. The levels of GSH and enzyme activities of SOD, GSPx and GR in liver and kidney were significantly decreased in comparison with controls. In CCl4＋MA-treated group, the changes in the levels of LPO in serum of liver and kidney were not statistically significant compared to controls. The levels of SOD, GSPx and GR in liver and kidney were significantly increased in comparison with controls. There was a significant differ- ence in urinary excretion of 8-OHdG between the CCh- treated and MA-treated groups. CONCLUSION： Oxidative stress may be a major mechanism for the toxicity of CCh. MA has a protective effect against CCl4 toxicity by inhibiting the oxidative damage and stimulating GST activities. Thus, clinical application of MA should be considered in cases with carbon tetrachloride-induced injury.

Estrogen inhibits lipid peroxidation after hypoxic-ischemic brain damage in neonatal rats

Sprague-Dawley neonatal rats within 7 days after birth were used in this study. The left common carotid artery was occluded and rats were housed in an 8% O2 environment for 2 hours to establish a hypoxic-ischemic brain damage model. 17β-estradiol （1 × 10-5 M） was injected into the rat abdominal cavity after the model was successfully established. The left hemisphere was obtained at 12, 24, 48, 72 hours after operation. Results showed that malondialdehyde content in the left brain of neonatal rats gradually increased as modeling time prolonged, while malondialdehyde content of 17β-estrodial-treated rats significantly declined by 24 hours, reached lowest levels at 48 hours, and then peaked at 72 hours after injury. Nicotinamide-adenine dinucleotide phosphate histochemical staining showed the nitric oxide synthase-positive cells and fibers dyed blue/violet and were mainly distributed in the cortex, hippocampus and medial septal nuclei. The number of nitric oxide synthase-positive cells peaked at 48 hours and significantly decreased after 17β-estrodial treatment. Our experimental findings indicate that estrogen plays a protective role following hypoxic-ischemic brain damage by alleviating lipid peroxidation through reducing the expression of nitric oxide synthase and the content of malondialdehyde.

Studies on Free Radical EPR,Superoxide Dismutase Water-soluble Lipidperoxide in Tears

By means of electron paramagnetic resonance(EPR), chemistry luminescence and fluorescent spectroscopy, the free radical, superoxide dismutase and water soluble lipid peroxide in tears of normal eyes(150 eyes, 100 cases), Moorens ulcer(9 eyes), coreal grafts rejection(16 eyes) were studied. The results showed that the spin density of the free radical was 36(±058)×1012 spins/mL tear, the content of the superoxide dismutase(SOD) was 384(±145) ng/mL tear, the opposite fluorescent density of the water soluble lipid peroxide was 12912(±1691) U/mL tear in normal tears. The normal values are 25—48×1012 spins/mL tear for free radical, 239—529 ng/mL tear for SOD, 9598—16225 U/mL tear for water soluble lipid peroxide. There are significant differences in different eyes, different sexes and different ages. The free radical and lipid peroxide are higher obviously in the tears of patients with Moorens ulcer and rejected corneal grafts, compared with those of the normal control subjects(P<001), SOD is lower evidently(P<001). The above fact shows the pathogenic mechanism of Moorens ulcer and keractoplasty rejection is significantly related to toxicities injuring effect of the free radical. These results have provided important experimental data for studying lacrimalogy and new methods for clinical diagnosis and treatrment.

CLINICAL SIGNIFICANCE OF VITAMIN C TO AMELIORATE LIPID PEROXIDATION DAMAGE IN CORONARY ARTERY DISEASE

The activities of superoxide dismutase (SOD). glutathione peroxidase (GSH-PX) in blood and the content of melondialdehyde (MDA) in plasma of 30 Fatients (male 17, female 13) with coronary artery disease (CAD) were determined in this study. It was shown that SOD and GSH-PX activities were decreased and the content of MDA was increased in the Patients comparative with the healthy controls (P<0.001). Vitamin C, the free radical scavenger, was then administered intravenously with a daily dose of 2g for 2 weeks. The activities of SOD and GSB-PX were significantly elevated (P<0.01, and P<0.05, respectively). and the level of MDA was obviously declined (P<0.01). Thus,the lipid peroxidation is involved in the pathogenesis of CAD,and vitamin C possessing some effects to ameliorate the lipid peroxidation damage could be helpful in the treatment of CAE.

Free-Radical Conjugated Oxidation of Natural Methane by Hydrogen Peroxide

There has been carried out the process of noncatalytic oxidation of natural methane in the presence of hydrogen peroxide at the temperatures 840-880 ℃ what permitted to obtain hydrogen with high yield of hydrogen （74%） with inconsiderable quantity of CO （0.4%） in converted gas. As observed in the experiment, a variation of H2O2 concentration in the aqueous solution and other basic parameters of the process may induce the synthesis of gas with given H2：CO ratio for its further application in methanol or ammonia synthesis. In the latter process low CO concentration is required. Compared with the common high-temperature conversion of natural gas and further carbon oxide conversion on a catalyst, the current process promotes process simplification： the reaction is implemented at relatively low temperature （860-900 ℃ instead of 1400-1600 ℃for existing non-catalytic processes of methane conversion） and an additional unit for catalytic conversion of carbon oxide is excluded （in NH3 production）. The mechanism of chemical conjugation in the CH4-H2O2-H2O system was elucidated and the inducing effect of H2O2 decomposition on the desired （secondary） reaction was quantitavely estimated. An adequate kinetic model was formulated on the basis of the proposed free-radical scheme.

高维生素C刺梨饼干配方工艺优化及其体外抗氧化作用

以刺梨为基本原料,制作一款高维生素C(VC)含量的刺梨饼干,并对其配方工艺进行优化,对其体外抗氧化活性进行评价.采用4因素4水平正交试验设计,对影响刺梨饼干制作中VC含量和稳定性的4个关键因素烘焙温度、烘焙时间、苹果酸用量和红花籽油用量进行优化;采用不同种类的普通食用油等量替代优化配方中的红花籽油,观察并对比普通食用油和红花籽油对产品中VC含量的影响;通过测定产品对羟基自由基和超氧阴离子自由基的清除率及对脂质过氧化的抑制率来评价产品的体外抗氧化活性.结果得到最优的产品配方工艺条件为:烘焙温度为140℃,烘焙时间为20 min,苹果酸用量为0.75%,红花籽油用量为8%.产品中的红花籽油采用普通食用油替代后,起酥油的VC损失率最大,比红花籽油高4.8倍以上,普通植物食用油的VC损失率也比红花籽油高89%以上.按优化后的配方工艺制得的刺梨饼干产品中VC含量达210 mg/100 g,质量稳定.优化后的产品和等剂量VC对照组对羟基自由基和超氧阴离子自由基都有良好的清除作用,对脂质过氧化有良好的抑制作用,并且优化后的产品效果都显著优于等剂量的VC对照组.

体外模拟胃肠消化过程中云南金花茶抗氧化能力变化

为探究云南金花茶在消化过程中总黄酮、总多酚释放及功能活性的变化情况,该研究采用体外模拟胃肠消化模型测定了云南金花茶消化液中总黄酮、总多酚浓度及自由基清除能力、铁离子还原能力和脂质过氧化抑制能力,并对其进行了相关性分析。结果表明,模拟胃消化过程中,云南金花茶总黄酮、总多酚含量均比口腔消化高,最高分别达229.99、327.65µg/mL,经肠消化后,总黄酮含量在38.56~78.88µg/mL之间,总多酚含量在30.04~65.52µg/mL之间,含量较低。在功能活性测定中,较口腔消化,胃消化阶段的DPPH·、ABTS+·清除能力和铁离子还原能力显著升高,脂质过氧化抑制能力随消化的进行呈上下波动;经肠消化后,DPPH·、ABTS+·清除能力和铁离子还原能力急剧下降,且均比胃消化阶段低,而脂质过氧化抑制能力则趋于平稳或逐渐上升。通过相关性及主成分分析,各指标之间存在一定的关联性。综上所述,云南金花茶是较好的活性物质来源,该研究可为探索云南金花茶在人体消化过程中活性物质的变化及作用机制提供一定的实验基础和新思路。

过氧化物类芬顿体系修复有机污染物的研究进展

环境中有机污染物种类繁多,例如有机卤代物、有机农药和苯系物等。过氧化物常被作为自由基前驱体。过氧化物类芬顿系统是实现环境中有机污染物修复的有效技术手段,通过产生羟基等自由基将环境中有机污染物转化为易分解的小分子、CO_(2)和H_(2)O。本文综述了部分学者对过氧化物类芬顿体系降解环境中有机污染物性能、影响因素的研究进展,阐述了过氧化物类芬顿体系存在的问题,以期为过氧化物类芬顿体系修复环境中有机污染物提供理论技术支撑。

老挝某含砷金矿非氰浸出试验研究

对老挝某含砷含碳金矿进行了非氰浸出试验研究,考察了磨矿细度、矿浆pH值、矿浆浓度(质量分数)、金蝉环保型黄金选矿剂用量对金浸出效果的影响。结果表明:采用过氧化氢预处理可以提升金浸出率;在磨矿细度-0.074 mm粒级占95%、搅拌速度2000 r/min条件下,采用过氧化氢500 g/t对矿浆预氧化处理3 h,然后再添加石灰3000 g/t、金蝉环保型黄金选矿剂5000 g/t,搅拌浸出30 h,尾渣金品位0.25 g/t,金浸出率92.27%,过氧化氢预氧化能使金浸出率提高1.96个百分点。

Reduction of hydrogen peroxide-induced erythrocyte damage by Carica papaya leaf extract

Objective:To investigate thein vitroantioxidant potential of Carica papaya(C. papaya) leaf extract and its effect on hydrogen peroxide-induced erythrocyte damage assessed by haemolysis and lipid peroxidation.Methods:Hydroxyl radical scavenging activities, hydrogen ion scavenging activity, metal chelating activity, and the ferrous ion reducing ability were assessed as antioxidant indices. In the other experiment, human erythrocytes were treated with hydrogen peroxide to induce erythrocyte damage. The extract(at various concentrations) was subsequently incubated with the erythrocytes and later analysed for haemolysis and lipid peroxidation as indices for erythrocyte damage.Results:Preliminary investigation of the extract showed that the leaf possessed significant antioxidant and free radical scavenging abilities usingin vitro models in a concentration dependent manner(P<0.05). The extract also reduced hydrogen peroxide induced erythrocyte haemolysis and lipid peroxidation significantly when compared with ascorbic acid(P<0.05). The IC50values were 7.33 mg/mL and 1.58 mg/mL for inhibition of haemolysis and lipid peroxidation, respectively. In all cases, ascorbic acid(the reference antioxidant) possessed higher activity than the extract.Conclusions:The findings show that C. papayaleaves possess significant bioactive potential which is attributed to the phytochemicals which act in synergy.Thus, the leaves can be exploited for pharmaceutical and nutritional purposes.

NMR used to study the side-reactions between peroxides and antioxidants during the reactive extrusion process of the impact polypropylene

Side reaction pathways are observed to occur between antioxidants and peroxide during the processing of multiple resin grades mediated by controlled peroxide-induced degradation of impact polypropylene.In the present work,the reaction mechanism and main by-products between antioxidants and peroxides were investigated.The results demonstrate that peroxides greatly accelerate the decomposition reactions,and the free radicals formed from peroxide decomposition react with,for example,the antioxidant AO1010 to produce dehydrogenation of phenyl propionic unit(s)at the a position(cinnamic acid ester moiety),which generates a conjugated system leading to the increased color of the product.It is the first time to confirm the cinnamic acid moiety's existence and report its NMR data.Further,this work confirms the dehydrogenation mechanism by comparison with different sterically hindered phenolic antioxidants.It also systematically summarizes the oxidation and degradation mechanism of AO168 and AO1010 under air and peroxide environments,respectively.Based on present study,clear guidelines are obtained to improve the quality of polymeric products,especially the appearance and stability,during product development.

Biodiesel Resistance of Thin Resin Cr-Free Steel Sheets for Fuel Tank

The content of biodiesel mixed with diesel fuel were compared to inspect the fuel resistance of thin resin Cr-free steel sheets, which are widely used as steel sheets of automobile fuel tank. Some additives which can be presented during the process of biodiesel preparation were added for CCT (Cyclic Corrosion Test). These additives can accelerate the occurrence of corrosion. The corrosion was appeared on the coating and painting layer and in serious cases even substrate material was corroded. For methanol, mixing with blended fuel showed the reduction in corroded area as the additive concentration was reduced in the mixed fuel. Especially the peroxide hydrogen showed the strongest corrosiveness. It is known that formic acid has a tendency of weaker corrosiveness than peroxide hydrogen, but the corrosion is occurred throughout the specimen. Water is not mixed well with fuel, and does not seem to impact on corrosion significantly. However, water is easily mixed with other additives and is considered to facilitate the corrosion by other additives.

EFfect of verbascoside on decreasing concentration of oxygen free radicals and lipid peroxidation in skeletal muscle

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基于纳米酶的无抗生素抗菌策略

抗生素是抵抗细菌感染的有力武器,然而抗生素的过量使用和滥用加速了细菌耐药性的发展,严重威胁人类健康。开发高效和广谱的无抗生素抗菌策略迫在眉睫。以过氧化氢(H_(2)O_(2))为代表的活性氧(reactive oxygen species,ROS)能氧化多种生物分子,使其结构和活性改变而发挥广谱抗菌作用,是无抗生素抗菌策略之一。然而,临床常用的H_(2)O_(2)浓度较高(0.5%~3%),会刺激皮肤和延缓伤口愈合。利用过氧化物酶催化H_(2)O_(2)生成氧化性更强的羟自由基(·OH),可大幅提高ROS抗菌策略的性能。然而,天然酶生产成本高、稳定性低等缺点限制了该策略的推广。纳米酶是具有类似天然酶催化活性的纳米材料的统称。与天然酶相比,纳米酶具有制备简单、成本低和易储存等优势,是开发基于ROS的无抗生素抗菌策略的良好选择。贵金属、金属氧化物、金属硫化物、金属有机框架、碳基纳米材料等多种纳米材料具有过氧化物酶、氧化酶等的模拟催化活性,基于这些材料的纳米酶抗菌研究层出不穷,本文将对这些研究进行归纳和介绍,并对纳米酶抗菌应用研究中存在的问题进行讨论。

无金属光催化剂催化过氧化氢生产的研究进展

过氧化氢(H_(2)O_(2))是一种绿色强效氧化剂,能够在温和条件下氧化液体介质中的多种有机和无机基质,与化学计量氧化剂相比,其活性氧含量高,且只释放H_(2)O和O_(2)作为最终产物,具有环保高效的独特优势。相对于传统的蒽醌产H_(2)O_(2)工艺,光催化过程具有低耗、环保、安全等的优势。无金属光催化剂由于其合成简单、成本低、环境友好、生物相容性高等的特征成为光催化产H_(2)O_(2)的理想光催化剂之一。文章论述了无金属光催化剂近年来在光催化产H_(2)O_(2)领域最新进展。主要包括:光催化产H_(2)O_(2)的基本机理及过程以及石墨氮化碳(g-C_(3)N_(4))、共价有机框架(COFs)、有机聚合物主要无金属光催化剂的特征及其在光催化产H_(2)O_(2)重要进展。讨论了现阶段光催化产H_(2)O_(2)研究中遇到的问题和挑战,并提出一些见解和方法,特别是在光催化产H_(2)O_(2)机理过程、催化剂稳定性和H_(2)O_(2)分离、光催化产H_(2)O_(2)速率提升方面。该综述旨在促进光催化产H_(2)O_(2)的发展及应用。