Formation of Superoxide Radical and Hydrogen Peroxide Enhanced by Trinitrotoluene in Rat Liver, Brain, Kidney, and Testicle in Vitro and Monkey Liver in Vivo

Trinitrotoluene (TNT) increased the formation of adrenochrome from adrenaline and the formation of formaldehyde from methanol in rat liver mitochondria and microsomes in vitro as well as in monkey liver mitrochondria and microsomes in vivo. The effects were more prominent at higher TNT concentrations. These findings indicate that TNT enhances the production of superoxide radicals (O_2^-) and hydrogen peroxide (H_2O_2). The production of O_2^- was more prominent in systems containing added TNT than in those containing added benzyl viologen. H_2O_2 production by mitochondria was more pronounced in the liver than in other organs, but its production by microsomes was more pronounced in the brain than in other organs. The results suggest that TNT undergoes cycling reduction which produces oxidative stress. 1989 Academic Press, Inc.

EPR study of charge separation associated states and reversibility of surface bound superoxide radicals in SrTiO_(3) photocatalyst

Understanding the processes of charge generation, transfer and capture is important for the design and synthesis of efficient photocatalysts. In this work, light-induced charge separation and effect of O_(2) on electron transfer processes in SrTiO_(3) were investigated by electron paramagnetic resonance(EPR). It was found that photoinduced electron transfer from O_(2)- to Ti^(4+) produced Ti^(3+) and O- redox radical pairs under vacuum condition. Under oxygen atmosphere, however, surface bound superoxide radicals O_(2)-were formed by electron reduction of adsorbed oxygen at initial photoirradiation stage, and quenched by the reverse electron transfer to Ti^(4+) upon further photoirradiation. Formation of long-lived charge separation associated [Ti^(3+)---O-] species and the reversibility of surface bound superoxide radicals mediating the processes of photogenerated electrons may be accountable for the high activity of SrTiO_(3) in photocatalytic water splitting reaction.

Preparation of (±)-5,6,7-Trioxygenated Dihydroflavonols and Evaluation of their Superoxide Radical Scavenging Activity

The synthesis of （±）-5, 6, 7-trioxygenated dihydroflavonols was carried out. All synthetic compounds were passed through superoxide radical scavenging activity in vitro. Compounds 1 e and 1 g exhibited significant bioactivity with the inhibitory rates of 68.1% and 80.9% at 40 μg/mL, respectively.

Photocatalytic degradation kinetics and mechanism of pentachlorophenol based on superoxide radicals

The micron grade multi-metal oxide bismuth silicate （Bi 12 SiO 20,BSO） was prepared by the chemical solution decomposition technique.Photocatalytic degradation of pentachlorophenol （PCP） was investigated in the presence of BSO under xenon lamp irradiation.The reaction kinetics followed pseudo first-order and the degradation ratio achieved 99.1% after 120 min at an initial PCP concentration of 2.0 mg/L.The pH decreased from 6.2 to 4.6 and the dechlorination ratio was 68.4% after 120 min at an initial PCP concentration of 8.0 mg/L.The results of electron spin resonance showed that superoxide radical （O 2 · ） was largely responsible for the photocatalytic degradation of PCP.Interestingly,this result was different from that of previous photocatalytic reactions where valence band holes or hydroxyl radicals played the role of major oxidants.Some aromatic compounds and aliphatic carboxylic acids were determined by GC/MS as the reaction intermediates,which indicated that O 2 · can attack the bond between the carbon and chlorine atoms to form less chlorinated aromatic compounds.The aromatic compounds were further oxidized by O 2 · to generate aliphatic carboxylic acids which can be finally mineralized to CO 2 and H 2 O.

Reinventing MoS2 Co-catalytic Fenton reaction:Oxygen-incorporation mediating surface superoxide radical generation

To better understand the mechanisms of hydrogen peroxide(H_(2)O_(2))’s decomposition and reactive oxygen species(ROS)’s formation on the catalyst’s surface is always a critical issue for the environmental application of Fenton/Fenton-like reaction.We here report a new approach to activate H_(2)O_(2) in a co-catalytic Fenton system with oxygen incorporated MoS2,namely MoS_(2−x) O_(x) nanosheets.The MoS_(2−x) O_(x) nanosheets assisted co-catalytic Fenton system exhibited superior degradation activity of emerging antibiotic contaminants(e.g.,sulfamethoxazole).Combining density functional theory(DFT)calculation and experimental investigation,we demonstrated that oxygen incorporation could improve the intrinsic conductivity of MoS_(2−x) O_(x) nanosheets and accelerate surface/interfacial charge transfer,which further leads to the efficacious activation of H_(2)O_(2).Moreover,by tuning the oxygen proportion in MoS_(2−x) O_(x) nanosheets,we are able to modulate the generation of ROS and further direct the oriented-conversion of H_(2)O_(2) to surface-bounded superoxide radical(·O_(2−surface)).It sheds light on the generation and transformation of ROS in the engineered system(e.g.,Fenton,Fenton-like reaction)for efficient degradation of persistent pollutants.

Mechanism of Cerium Ions Scavenging Superoxide Radical

The mechanism of cerium ions scavenging superoxide radical(O÷2) has been studied. The results show that (1) Ce^3+ can reduce O÷2 to H_2O_2 while it is oxidized to Ce^4+; (2) Ce^4+ can oxidize O÷2 to O_2 while it is reduced to Ce^3+.

SUPEROXIDE RADICAL SCAVENGING AND CYTOTOXIC EFFECTS OF DIFFERENT MARINE SPECIES FROM TURKEY'S COASTS

In this study,acetone extracts of thirteen different species distributed in Turkey Coasts including tunicates,sea anemones,sponges and corals were investigated for their superoxide(SO)radical scavenging and cytotoxic activities.VWhile SO radical scavenging activity was tested using alkaline DMSO method,cytotoxic activity was tested by MTT assay against Hep-2 cancer cell line.As a result of bioactivity studies,Paramuricea clavata extract showed

Superoxide Anion Radical Scavenging Ability of Quaternary Ammonium Salt of Chitosan

A series of N-alkyl or N-aryl chitosan quaternary ammonium salt were prepared using 96% deacetylated chitosan. Their scavenging activities against superoxide anion radical were investigated by chemiluminescence. The IC50 values of these compounds range from 280 to 880 μg/mL, which should be attributed to their different substitutes.

Study on Inhibition Effects of Rare Earths on Superoxide Anion Radical by Using Pulse Radiolysis

The inhibition effect of rare earths on the production of ·O - 2 produced by radiolysis of aqueous sodium formate saturated with O 2 with high energy pulse electron beam was studied. The result indicates that rare earth nitrate obviously inhibits the production of ·O - 2 . The inhibition rate is between 28 6% and 92%. The inhibition effect increases with the increase of rare earth nitrates concentration. The distinguish dose effect relationship was observed.

A New Method of Superoxide Free Radical Determination in Ischemia and Reperfusion Injury of Rat Liver

The present study was designed to utilize the chemiluminescence(CL)method for O2- analysis in ischemia and reperfusion of the whole rat liver. The results indicated that the O2- level was lower after 30 and 60 min ischemia. After 40 min reperfusion, the level of O2- increased obviously,reaching about 8. 3-fold (30min ischemia) and 9. 0-fold (60 min ischemia) (P<0.001,P<0.01) respectively.The results also show that Chinese Traditional Medicines ligustrazine and salvia compound can scavenge O2- effectively.

New Active Organic Substance in Oyster Shell Capable of Scavenging Oxygen Free Radicals with High Efficiency

A light purple organic active substance capable of scavenging hydroxyl radical（OH） with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical（O2） although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.

Hyperlipidemia and erectile dysfunction

We have done consecutive studies to investigate the effects of impaired lipid metabolism on the contractile and re-laxation response of cavernous smooth muscles and to elucidate its pathogenesis: 1) incidence of hyperlipidemia in im-potent patients; 2) erection response to intracavemous injection of papaverine in impotent patients with hyperlipidemia;3) relaxation responses of isolated cavemosal smooth muscles to endothelium-independent and endothelium-dependentvasodilators in impotent patients with hypercholesterolemia or hypertriglyceridemia; 4) involvement of superoxide radi-cal in the impaired endothelium-dependent relaxation of cavemous smooth muscle in hypercholesterolemic rabbits; S)effects of isolated lipoproteins and triglyceride, combined oxidized LDL plus triglyceride, and combined oxidized LDLplus HDL on contractile and relaxation response of rabbit cavemous smooth muscles; 6) involvement of e-NOS in theimpaired endothelium-dependent relaxation of cavemous smooth muscle in hypercholesterolemic rabbit. Hypercholes-terolemia may cause impairment of endothelium-dependent relaxation. Oxidized LDL is the major causative cholesterolof the impaired relaxation response. A chain reaction, the production of superoxide radicals and functional impairmentof eNOS may be a major cause of the functional impairment in the early stages of hypercholesterolemia.

Role of the reduction site in the fluorinated or sulfated TiO_2 photocatalytic process

In this article, the effects of ZiO2 surface fluorination and sulfation, on the active oxygen species formed at the reduction site in the photocatalytic process, namely O2^＊- and H2O2, were investigated from a new perspective. The superoxide radical, （O2^＊-）, was determined by colorimetry of nitroblue tetrazolium, a prominent O2^＊- scavenger. Hydrogen peroxide （H2O2） was estimated by using the iodide-starch method. In the naked TiO2 photocatalysis, O2^＊-, though less reactive, was a very important intermediate. When the TiO2 surface was fluorinated, more O2^＊- and H2O2 were produced, which indicated that the surface modification could greatly reduce the recombination of photogenerated electrons and holes, thus enhancing the photocatalytic rate. In the sulfated system, photocatalysis proceeded with a more complicated mechanism. These results added support to the view of fluoride-induced enhancement and sulfide＇s nonappreciable inhibition effect.

Synthesis, characterization, and biological activities of Pt(Ⅱ) and Pd(Ⅱ2',3',4',5,7-pentahydroxy flavone

Pt(Ⅱ) and Pd(Ⅱ) complexes with 2′,3′,4′,5,7-pentahydroxy-flavone weresynthesized and characterized by elemental analysis, molar conductance, IR, ~1HNMR, TG-DTA, UV-Visspectroscopic techniques, and fluorescence analysis. The scavenging effect on the superoxide radical(O_2^-) and the inhibitory effect on lipid peroxides were also investigated. Both the ligand andthe complexes exhibit scavenging effect on superoxide radicals, and the effect of the complexes isgreater than that of the ligand. The Pt(Ⅱ) complex exhibits the strongest scavenging efficiency.Both Pt(Ⅱ) and Pd(Ⅱ) complexes have the inhibitory effect on lipid peroxides, and the effect ofthe complexes is greater than that of the ligand, but the Pt(Ⅱ) complex has a high effect ofpromoting lipid peroxides.

Antioxidant Activity of Pigment Extracted from Green-Wheat-Bran

The anthocyanin pigment extracted from green-wheat-bran was studied to identify its antioxidant activity.The antioxidant activities of the pigment were evaluated by anti-lipid peroxidation,total antioxidant activity （TAA）,superoxide anion radical scavenging activity （SARSA）,active oxygen scavenging activity （AOSA）,and DPPH （1,1-diphenyl-2 picrylhydrazyl free radical） radical scavenging activity.The results showed that the pigment had higher antioxidant activity and TAA,SARSA,AOSA and DPPH.scavenging activities at a certain concentration than Vc （antiscorbutic vitamin,vitamin C）,and the capacity increased with the increase of pigment concentration.Its TAA was 51.06 U mL-1,1.73 times of Vc,and SARSA 18 025.21 U mL-1,2.26% higher than Vc,and AOSA 3 776.31 U mL-1,1.24 times of Vc.As to the DPPH.scavenging activity of the pigment,there was a trend that higher concentration performed higher activity significantly improved with the company of Vc.The pigment showed significant antioxidant activities evaluated by different assays.Results will provide a better understanding on antioxidant activity of green wheat and allow the screening or breeding of green wheat varieties with higher antioxidant activity for food processing.

Determination of photochemically-generated reactive oxygen species in natural water

Reactive oxygen species （ROS） can be produced by interactions between sunlight and light-absorbing substances in natural water environment. ROS may participate in the indirect photolysis of trace organic pollutants, therefore resulting in changes in their environmental fates and ecological risks in natural water systems. Bisphenol A （BPA）, an endocrine-disrupting chemical, exits widely in natural waters. The photodegradation of BPA promoted by ROS （-OH, 1O2, HO2./O2^-）, which were produced on the excitation of ubiquitous constituents （such as nitrate ion, humic substances and Fe（Ⅲ）-oxalate complexes） in natural water under simulated solar radiation was investigated. Both molecular probe method and electron spin resonance （ESR） test were used for the characterization of the generated ROS. It was found that .OH was photochemically produced in the presence of nitrate ions, humic substances and Fe（Ⅲ）-oxalate complexes and that 102 was produced with the presence of humic substances. The steady-state concentrations of .OH was 1.27×10^-14 mol/L in a nitrate solution, and the second-order rate constant of BPA with ＂OH was 1.01×10^10 L/（mol.s）.

Molecular cloning and functional characterization of a soybean GmG MP1 gene reveals its involvement in ascorbic acid biosynthesis and multiple abiotic stress tolerance in transgenic plants

L-Ascorbic acid （AsA） plays an important role in plants and animals. In plants, GDP-D-mannose pyrophosphorylase （GMP） is essential in the AsA biosynthetic pathway. However, little is known about the genes encoding GMP in soybean and here we report genetic and functional analysis of the GmGMP1 （Glycine max GDP-D-mannose pyrophosphorylase 1） gene in this species. GmGMP1 encoded a GDP-mannose pyrophosphorylase and exhibited higher transcript levels in the leaf than in the root, stem, flower, and seed. Transcript of this gene was ubiquitous in the vegetative and reproductive organs, and was induced by abiotic stress and light. Increasing expression of GmGMP1 in Arabidopsis and soybean through an overexpressing approach caused pronounced enhancement of AsA content, and was implicated in lowering the superoxide anion radical content and lipid peroxidation levels in Arabidopsis, and conferring tolerance to osmotic and high salt stresses during seed germination. The present study represents the first systematic determination of soybean genes encoding GDP-mannose pyrophosphorylase and provides useful evidence for the functional involvement of GmGMP1 in control of AsA content and conferring tolerance to osmotic and salt stress.

Superoxide-like Cu/GO single-atom catalysts nanozyme with high specificity and activity for removing superoxide free radicals

Although nanozyme has become an emerging area of research attracting extensive attention recently,the activity and specificity of currently reported nanozymes are generally lower than those of natural enzymes.Developing highly active and specific nanozymes is therefore extremely necessary and also remains a great challenge.Superoxide dismutase(SOD)catalyzes the disproportionation of cytotoxic O_(2)·^(−)into hydrogen peroxide and oxygen,and plays an important role in reducing human oxidative stress.In this work,we prepare Cu single-atom catalysts(Cu/GO SACs,GO=graphene oxide)through a simple and low-cost strategy at room temperature using Cu foam and graphene oxide.Cu/GO SACs can maintain excellent catalytic activity under harsh environment.Compared with the natural enzyme,SOD-like Cu/GO SAC nanozyme has higher catalytic activity and meanwhile,it does not possess the common properties of other mimic enzymes often existing in nanomaterials.Based on the excellent SOD-like enzyme activity of Cu/GO SACs,it successfully eliminates the active oxygen in cigarette smoke.This work not only provides a new idea for the design and synthesis of nanozymes with excellent SOD mimetic properties,but also is promising in the treatment of lung injury and inflammatory diseases related to free radical production.

Preparation of Elemental Tellurium Nanoparticles-Sucrose Sol and Its Antioxidant Activity in Vitro

The elemental tellurium nanoparticles （TeNPs） - sucrose sol was prepared by the reaction of sodium tellurite with ascorbic acid in sucrose aqueous solution. The results indicated that TeNPs were dispersion excellent in the TeNPs - sucrose sol and the morphology of TeNPs was needle-like with about 70 nm in width and 500 nm in length. The antioxidant activity of the TeNPs - sucrose sol in vitro was estimated by pyrogallol autoxidation method, Fenton method and oxygen radical absorbance capacity （ORAC） assay. The results showed that a certain amount of TeNPs - sucrose sol could effectively scavenge superoxide anion free radical and hydroxyl free radical with scavenging rates of 73 % and 57 %, respectively. ORAC assay was used to measure the total antioxidant capacity of TeNPs - sucrose sol. The order of ORAC values was 2.25 μmol.L-1 TeNPs - 0.025 % sucrose sol 〉 0.025 % sucrose 〉 2.25 μmol.L-1 Na2TeO3 〉 1.63 μmol.L-1 ascorbic acid. The results suggested that the TeNPs - sucrose sol had the excellent antioxidant activity and TeNPs were the dominating contributors to antioxidant capacity of the TeNPs - sucrose sol.

光响应有机模块自组装导致的氧自由基转化及其光催化应用

在光催化反应中实现对活性氧物种的单线态氧和超氧阴离子自由基的有效控制仍然是一个巨大挑战.本工作报道了一个从光敏模块构筑主客体超分子有机框架(SOF)策略,有效地实现了单线态氧到超氧阴离子自由基的转化.该TPA-BP-SOF结构中的光敏模块由四个4,4′-联吡啶盐(BP)单元修饰的苯基桥接双(三苯胺)衍生物(TPA-BP)构成.来自于不同的TPA-BP中的两个BP单元通过与葫芦[8]脲(CB[8])发生首尾相连的强络合作用,形成了具有周期性孔结构和均匀溶解度的二维超分子有机框架纳米片结构.与单体TPA-BP中检测到的生成单线态氧的能量转移机制不同,通过主客体相互作用形成的TPA-BP-SOF能够有效促进电子转移高效产生超氧阴离子自由基.同时,该TPA-BP-SOF生成的超氧阴离子自由基能有效地用于水相芳基硼酸的氧化羟基化和N-苯基四氢异喹啉的氧化,收率分别高达88%和83%.本研究提出了一种利用SOF实现II型光敏剂向I型光敏剂有效转化的新方法,成功展示了其在光催化有机转化中的实际应用.