CuCl-catalyzed Oxidative N-Demethylation of Arylamines with tButyl Hydroperoxide

CuCl-catalyzed oxidative N-demethylation of arylamines proceeded in the presence of tert-butyl hydroperoxide. The one-electron transfer route of oxidative N-demethylation competed favorably with the H-atom abstraction route.

Oxidation of Dibenzothiophene in Model Diesel Using Hydroperoxide Generated via In-Situ Reaction of Octane with Oxygen

The potential of carrying out oxidative desulfurization(ODS) using oxygen as an oxidant was explored in this work. n-Octane firstly reacted with oxygen to produce hydroperoxides in-situ, which were then used as oxidants to oxidize the dibenzothiophene(DBT) in the absence of catalysts. The hydroperoxides generated in-situ were effective in oxidizing DBT to its corresponding dibenzothiophene sulfone(DBTO_2) which was characterized by FT-IR and ~1H-NMR. The removal rate of DBT could reached 98.4% under conditions covering a temperaure of 140℃, a rection duration of 4 h, and an oxygen partial pressure of 0.4 MPa. The influences of different hydrocarbon components in diesel on DBT removal were investigated. The results showed that cyclohexane and n-dodecane had no effect on the removal of DBT, but xylene had a slight negative effect on DBT removal. A possible oxidation mechanism was proposed and the concentration of hydroperoxides in both O_2-oxidized octane and model diesel were detected.

Oxidation of Benzothiophenes Using Tert-amyl Hydroperoxide

Homogeneous oxidation using an oil-soluble oxidant,tert-amyl hydroperoxide(TAHP),for ultra-deep desulfurization was performed under mild conditions in the presence of molybdenum oxide catalysts.Dibenzothio-phene(DBT),benzothiophene(BT) and 4,6-dimethyl-dibenzothiophene(DMDBT),which are the refractory sulfur compounds for hydrodesulfurization(HDS),were employed as model substrates for a simulated diesel fuel.Activity of molybdenum oxide supported on a macroporous weak acidic resin was investigated.The mass conversion of DBT reached near 100% at 90°C and a TAHP/DBT molar ratio of 3 with 1% of molybdenum oxide supported on Amberlite IRC-748 resin for 1 h.It was further found that the activities of the model substrates decreased in the or-der of DMDBT>DBT>BT.In the flow oxidation using TAHP as the oxidant,mass conversion of DBT increased remarkably from 61.3% to 98.5% when dropping the weight hourly space velocity(WHSV) from 40 h-1 to 10 h-1.A series of experiments dealt with selectivity of this oxidation using TAHP revealed that the model unsaturated compounds,i.e.4,6,8-trimethyl-2-nonylene,and 2-methylnaphthalene did not affect the oxidation of DBT.Car-bazole had nearly no effect on the conversion of DBT using TAHP,but had some influence on the one using tert-butyl hydroperoxide(TBHP).The mass conversion of DBT decreased remarkably from 75.2% to 3.6% when the content of carbazole increased from 0 to 500 μg·g-1.In the flow oxidation using TAHP as the oxidant,the concentration of DBT in model fuels was reduced from 500 μg·g-1 to 7.2 μg·g-1 at WHSV of 10 h-1,and then reduced to 3.8 μg·g-1 by adsorption of Al2O3.

Characterization of two alkyl hydroperoxide reductase C homologs alkyl hydroperoxide reductase C_H1 and alkyl hydroperoxide reductase C_H2 in Bacillus subtilis

AIM: To identify alkyl hydroperoxide reductase subunit C(AhpC) homologs in Bacillus subtilis(B. subtilis) and to characterize their structural and biochemical properties. AhpC is responsible for the detoxification of reactive oxygen species in bacteria.METHODS: Two AhpC homologs(AhpC_H1 and AhpC_H2) were identified by searching the B. subtilis database; these were then cloned and expressed in Escherichia coli. AhpC mutants carrying substitutions of catalytically important Cys residues(C37S, C47 S, C166 S, C37/47 S, C37/166 S, C47/166 S, and C37/47/166 S for AhpC_H1; C52 S, C169 S, and C52/169 S for AhpC_H2) were obtained by site-directed mutagenesis and purified, and their structure-function relationship was analyzed. The B. subtilis ahp C genes were disrupted by the short flanking homology method, and the phenotypes of the resulting AhpC-deficient bacteria were examined.RESULTS: Comparative characterization of AhpC homologs indicates that AhpC_H1 contains an extra C37, which forms a disulfide bond with the peroxidatic C47, and behaves like an atypical 2-Cys AhpC, while AhpC_H2 functions like a typical 2-Cys AhpC. Tryptic digestion analysis demonstrated the presence of intramolecular Cys37-Cys47 linkage, which could be reduced by thioredoxin, resulting in the association of the dimer into higher-molecular-mass complexes. Peroxidase activity analysis of Cys→Ser mutants indicated that three Cys residues were involved in the catalysis. AhpC_H1 was resistant to inactivation by peroxide substrates, but had lower activity at physiological H2O2 concentrations compared to AhpC_H2, suggesting that in B. subtilis, the enzymes may be physiologically functional at different substrate concentrations. The exposure to organic peroxides induced AhpC_H1 expression, while AhpC_H1-deficient mutants exhibited growth retardation in the stationary phase, suggesting the role of AhpC_H1 as an antioxidant scavenger of lipid hydroperoxides and a stress-response factor in B. subtilis. CONCLUSION: AhpC_H1, a novel atypical 2-Cys AhpC, is functionally distinct from AhpC_H2, a typical 2-Cys AhpC.

Oxidation of Cyclohexane Catalyzed by TS-1 in Ionic Liquid with Tert-butyl-hydroperoxide

一有效并且环境联盟者友好过程为环己烷的氧化为容易的产品隔离被描述， tert-butyl-hydroperoxide 由钛硅石催化清淡 1 (TS-1 ) 在周围温度的离子的液体[emim ] BF4.Good 产量和产品的更高的选择在离子的液体被发现与相比在里面分子的溶剂。研究结果证明环己烷， 97.6% cyclohexanol 和甲基环己酮选择的 13.2% 变换在 90 ° C 的温和条件下面在离子的液体被获得。

Novel Hydroperoxides of 1-Imino-3,3-Disubstituted-1,3-Dihydro Isobenzofuran

Some 1-imino-3,3-disubstituted-1,3-dihydro isobenzofuran and 2-(1,1-disubstituted hydroxymethyl) benzamide derivatives have been obtained by the aminolysis of phthalide in the presence of triethylamine/aluminum chloride. 1-Benzylimino-3,3-disubstituted-1,3-dihydro isobenzofuran can be peroxidized to the corresponding hydroperoxides on exposure to the air for a long period. The structure was characterized by single crystal X-ray diffraction and the possible mechanism was suggested.

Urea-induced Inactivation and Unfolding of Recombinant Phospholipid Hydroperoxide Glutathione Peroxidase from Oryza sativa

Phospholipid hydroperoxide glutathione peroxidase is an antioxidant enzyme that has the highest capability of reducing membrane-bound hydroperoxy lipids as compared to free organic and inorganic hydroperoxides amongst the glutathione peroxidases.In this study,urea-induced effects on the inactivation and unfolding of a recombinant phospholipid hydroperoxide glutathione peroxidase（PHGPx）from Oryza sativa were investigated by means of circular dichroism and fluorescence spectroscopy.With the increase of urea concentration,the residual activity of OsPHGPx decreases correspondingly.When the urea concentration is above 5.0 mol/L,there was no residual activity.In addition,the observed changes in intrinsic tryptophan fluorescence,the binding of the hydrophobic fluorescence probe ANS,and the far UV CD describe a common dependence on the concentration of urea suggesting that the conformational features of the native OsPHGPx are lost in a highly cooperative single transition.The unfolding process comprises of three zones：the native base-line zone between 0 and 2.5 mol/L urea,the transition zone between 2.5 and 5.5 mol/L urea,and the denatured base-line zone above 5.5 mol/L urea.The transition zone has a midpoint at about 4.0 mol/L urea.

Hydroperoxides and cytokines as biomarkers in detecting atherosclerosis predisposition in cigarette smokers

Objectives: Smoking increases oxidative modification of LDL, associated with lower HDL plasma levels, systemic inflammatory response and endothelial dysfunction. We tested the hypothesis that the risk status for coronary atherosclerosis disease (CAD) of cigarettes smokers might be identified by means of serum oxidative levels and vascular inflammation determination. Design and Methods: Oxidative stress levels, cytokines, and the metabolic status were investigated on 499 subjects admitted to our institute. The association between biomarkers and smoking habits in the presence/absence of disease and with the number of vessel affected, was studied. Results: Oxidative stress and inflammatory levels (p < 0.001) were strongly induced by smoking habits. Serum values of the subjects categorised as CAD, non CAD and healthy subjects differed significantly (p < 0.001) only for the degree of oxidative stress. Glycaemia was able to affect C-reactive protein serum levels with a positive association (p < 0.05). The analysis of the study population indicated that serum oxidative stress levels significantly increased with increasing number of vessels affected (p < 0.01). When statistical analysis was performed separately in both smoking groups, smokers did not show any particular difference for both oxidative stress and inflammation markers between the two groups of cardiovascular patients (CAD and non CAD) and the control group, while for non smokers, the differences were evident. Conclusion: These findings indicate that the considered biomarkers, especially oxidative stress, can be useful to predict the biological damage caused by cigarette smoking, as well as to identify subjects characterised by a higher risk of cardiovascular event, but cannot evaluate the presence of disease in subjects with smoking habit.

Phospholipid Hydroperoxide Glutathione Peroxidase(PHGPx): More Than an Antioxidant Enzyme?

The family of glutathione peroxidases encompasses, as far, three tetrameric glutathione'peroxidases (GPx) and the monomeric PHGPx. Although the overall homology between tetrameric enzymes and PHGPx is less than 30%, a pronounced similarity has been detected on clusters involved in the active site and a common catalytic triad (selenocysteine glutamine and tryptophan) has been defined by structural and kinetic data.A major peculiar feature of the reaction catalyzed by PHGPx is the possibility to accommodate large lipophilic substrates. This accounts for the observed dramatic antiperoxidant effect and the synergism with vitamin E.Moreover, the reduction of lipid hydroperoxides accounts also for the observed modulation of cycloxygenase and inhibition of 15-lipoxygenase.On the other hand, structural and kinetic data indicate that also the specificity of PHGPx for the donor substrate is not restricted to GSH and the recent observation the PHGPx binds to specific mitochondrial proteins, from which it is released by ionic strength and thiols, suggests a possible fole of this seleooenzyme'in catalyzing the specific oxidation of protein thiols,thus modulating the activity of cellular regulatory elements. on this light, the selenium mojety of PHGPx, reacting much faster that thiols with a peroxide, and then oxidizing specific protein thiols, would channel the oxidation toward protein targets, thus providing, by protein-protein interaction, the specificity of the redox transition

Study on the Total Synthesis of Hainanolide (Ⅱ)──An Unexpected Hydroperoxide Containing Tricyclic Skeleton

An unexpected compound, hydroperoxide (4) formed from (3), the exo-cycloaddition product, which was synthesized through the Lewis acid catlyzed intramolecular Diels-Alder (IMDA) reaction. Its structure was confirmed by spectra and X-Ray diffraction analysis, An 1O2oxidation mechanism was proposed.

Product of the Schistosoma mansoni Glutathione Peroxidase Gene is a Selenium ContainingPhospholipid Hydroperoxide Glutathione Peroxidase (PHGPx) Sharing MolecularWeight and Substrate Specificity WithIts Mammalian Counterpart

In the blood fluke Schistosoma mansoni a functionally active, monomeric, phospholipid hydroperoxide glutathione peroxidase (PHGPx) has been purified and characterized. This enzyme contains a catalytically active selenocysteine. The protein has been shown to be the product of a cloned gene, previously referred to as a glutathione peroxidase gene. S. mansoni PHGPx has been found 5 times more abundant in female than in male worm extract. As in vertebrate PHGPx, homology alignment indicates that the residues involved in the glutathione binding by the tetrameric cellular glutathione peroxidase are mutated in the S. mansoni enzyme. Thus, this aspect appears a landmark of the PHGPx-type of glutathione peroxidases,which might be of functional relevance

基于AMPK/mTOR通路探讨注射用益气复脉对TBHP诱导H9c2细胞损伤的保护作用

目的:探讨注射用益气复脉(YQFM)通过AMPK/mTOR信号通路调控自噬减轻叔丁基过氧化氢(TBHP)所致H9c2心肌细胞损伤的机制。方法:体外培养H9c2心肌细胞,分为正常对照组、TBHP组、TBHP+YQFM组。CCK-8法检测各组H9c2心肌细胞存活率;免疫荧光检测细胞自噬情况;免疫印迹法检测各组细胞自噬相关蛋白LC3Ⅱ/LC3Ⅰ及AMPK/mTOR通路相关蛋白表达。结果:用2、4、8、16 g/L的YQFM预处理后,可显著恢复TBHP诱导的H9c2细胞损伤;免疫荧光染色结果显示,与正常对照组相比,TBHP组细胞LC3荧光强度显著升高(P<0.01);与TBHP组相比,TBHP+YQFM组LC3荧光强度降低,其中2 g/L YQFM组具有显著性(P<0.05)。Western blot检测结果显示:TBHP组p-AMPK/AMPK、LC3-Ⅱ/LC3-Ⅰ表达显著增加,p-mTOR/mTOR比率显著降低;YQFM预处理使自噬相关蛋白p-AMPK/AMPK、LC3-Ⅱ/LC3-Ⅰ比率明显降低,4 g/L YQFM组p-mTOR/mTOR比率明显升高。结论:注射用益气复脉能有效拮抗TBHP引起的H9c2细胞损伤,其机制与通过AMPK/mTOR信号通路调控自噬途径有关。

SBA-15分子筛负载对甲苯磺酸催化合成过氧化二异丙苯的性能和反应过程模拟

采用浸渍法制备了SBA-15分子筛负载对甲苯磺酸(TsOH)催化剂TsOH/SBA-15,探究了其催化α-甲基苯乙烯(α-MS)和异丙苯过氧化氢(CHP)反应制备过氧化二异丙苯(DCP)的活性,并对反应过程进行了模拟分析.当进料比n(α-甲基苯乙烯)/n(异丙苯过氧化氢)=2.0, TsOH/SBA-15用量为CHP质量的0.15%,于44℃反应2.5h, DCP的产率为62.1%.模拟计算结果表明,反应过程有异步协同反应和分步反应两种机理,在异步协同反应中α-MS, CHP和TsOH只需要经过一个过渡态即可完成,而分步反应中反应物需要经过两个过渡态以及一个中间体才能完成,两种路径均涉及2次H^(+)的转移.在44℃下,异步协同反应的反应能垒(ΔG)为121.8 kJ/mol,分步反应中两个过渡态对应的反应能垒分别为74.1和78.3 kJ/mol.

FeCu-C@MS催化臭氧氧化降解过氧化氢异丙苯废水的研究

过氧化氢异丙苯(CHP)作为一种典型的有机过氧化物,其废水会抑制生化系统活性,在实际处理中存在技术困难。本研究通过水热-浸渍法在球形分子筛表面负载Fe/HKUST-1,将其作为前驱体在350℃下碳化制备Fe/HKUST-1衍生碳@分子筛催化剂(FeCu-C@MS)。利用SEM、EDS、XRD等技术对催化剂进行表征,考察臭氧浓度、催化剂投加量、pH、初始CHP浓度等对FeCu-C@MS/O_(3)体系降解CHP的影响。结果表明:FeCu-C@MS/O_(3)体系在臭氧浓度为20 mg/L、催化剂投加量为50 g/L、pH为7、CHP初始浓度为12 mg/L的条件下,经过120 min反应CHP去除率可以达到65.47%,比O_(3)体系提高35.80%;经过5次循环使用后,CHP去除率仍可达到55.19%,表明FeCu-C@MS可以高效催化臭氧氧化降解过氧化氢异丙苯,且具有较好的稳定性和可重复利用性。

Highly selective photocatalytic oxidation of methane to methyl hydroperoxide

Partial oxidation of methane into primary oxidation products with high value remains a challenge.In this work,photocatalytic oxidation of methane(CH_(4))with high methyl hydroperoxide(CH_(3)OOH)selectivity is achieved using pure titanium oxide(TiO_(2))without any cocatalyst at room temperature and atmospheric pressure.The CH_(3)OOH production rate can reach up to 2050±88μmol·g^(-1)·h^(-1) at pH≈7.0 with 100%selectivity in the liquid product.The stable reaction cycle can reach more than 30 times.This low-cost system achieves superior CH_(4) conversion activity and selectivity compared with similar work.The energy of hydrogen peroxide(H_(2)O_(2))to adsorbed hydroperoxyl radical(^(*)OOH)has a significantly lower reaction energy than conversion to adsorbed hydroxyl radical(*OH)on the(210)surface of the TiO_(2).The^(*)OOH preferentially combines with methyl radical(·CH_(3))to form the most energetically favorable CH_(3)OOH.The mild oxidative environment of this system prevents the reduction of CH_(3)OOH to CH_(3)OH or over-oxidation of CH_(4),which ensures the final CH_(3)OOH with high selectivity and stability.This work provided a low-cost but highly efficient method to achieve partial oxidation with superior selectivity,i.e.,to convert CH_(4) into high-value chemicals.

过氧化物制药废水直接UV光降解及其资源化利用

实验采用直接UV光降解叔丁基过氧化氢(TBHP)废水,研究了TBHP的降解性能,分析了TBHP初始浓度、温度、pH值和无机离子共存对TBHP降解效率的影响。结果表明,当TBHP浓度为1.75g·L^(-1)、pH值为3时,TBHP的UV光降解遵循准一级动力学模型,表观降解速率常数达到0.217min^(-1),同时利用GC-MS分析了UV光降解TBHP的产物和路径。此外,实验研究了TBHP废水与其他工业废水混和后直接UV光降解的过程,结果表明,混合废水有机物降解效果优于单一废水,也为TBHP废水的资源化利用提供了新的途径。

奥美拉唑联合纤维蛋白粘合剂在消化性溃疡出血中的应用效果分析

目的探讨奥美拉唑联合纤维蛋白粘合剂在消化性溃疡出血中的应用效果。方法选取2020年5月至2022年5月信阳市第三人民医院收治的86例消化性溃疡出血患者作为研究对象,按照不同治疗方法将其分为联合组(43例)和单一组(43例),联合组患者在对症支持治疗的基础上采用奥美拉唑联合纤维蛋白粘合剂治疗,单一组患者在对症支持治疗的基础上单纯采用奥美拉唑治疗,对比观察两组患者血清谷胱甘肽过氧化物酶(GSH-Px)、脂质过氧化物(LPO)水平,胃组织内H^(+)-K^(+)-ATP酶活性及胃液酸碱度、凝血功能与临床疗效。结果治疗7 d后,联合组患者血清GSH-Px水平、胃液酸碱度均明显高于单一组(t=3315、2238,P=0001、0028),血清LPO水平、胃组织内H^(+)-K^(+)-ATP酶活性均明显低于单一组(t=3279、2651,P=0002、0010)。治疗2、7 d后,联合组患者凝血酶原时间、凝血酶时间、活化部分凝血活酶时间均明显短于单一组(治疗2 d后:t=2186、2250、2061,P=0032、0027、0042;治疗7 d后:t=2090、2003、2558,P=0040、0048、0012),纤维蛋白原水平均明显高于单一组(t=2199、2352,P=0031、0021)。联合组患者总有效率为9535%,明显高于单一组患者的总有效率8140%(χ^(2)=4074,P=0044)。结论与单纯应用奥美拉唑相比,奥美拉唑联合纤维蛋白粘合剂更能有效调节消化性溃疡出血患者GSH-Px、LPO水平,改善H^(+)-K^(+)-ATP酶活性、胃液酸碱度和凝血功能,治疗效果更好,临床应用价值更高。

灵芝孢子粉提取物延缓皮肤衰老作用研究

寻找天然有效成分以延缓皮肤衰老是近年来人们关注与研究的热点。为研究灵芝孢子粉提取物(Ganoderma lucidum spore extract,GLSE)对新生儿人真皮成纤维细胞(human dermal fibroblasts neonatal,HDFn)氧化损伤保护作用及其抗衰老作用,构建叔丁基过氧化氢(tert-butyl hydroperoxide,TBHP)诱导HDFn氧化损伤衰老模型,测定GLSE对衰老模型的保护作用以及细胞中超氧化物歧化酶(superoxide dismutase,SOD)活性、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活性以及丙二醛(malondialdehyde,MDA)水平、线粒体膜电位变化;同时测定衰老相关β-半乳糖苷酶活性以及抗氧化应激相关Nrf2/HO-1通路表达情况。结果显示,GLSE预处理后对TBHP诱导的衰老模型具有保护作用;GLSE作用HDFn后,能够降低MDA含量,提高细胞SOD和GSH-Px活性,稳定细胞线粒体膜电位,并且可以抑制细胞β-半乳糖苷酶活性,激活通路Nrf2/HO-1 mRNA表达。因此,GLSE作用于HDFn后,可以有效地减弱TBHP诱导的氧化损伤,从而达到延缓皮肤衰老的作用。