超氧阴离子自由基与嘧啶反应产物的量子化学研究

超氧阴离子自由基与嘧啶反应产物的量子化学研究班福强,戴柏青（哈尔滨师范大学,１５００８０）关键词超氧阴离子自由基;嘧啶;ＵＨＦ从头算超氧阴离子自由基（简称超氧自由基,）是一种重要的活性氧,与其他活性氧［如羟自由基（·ＯＨ）和过氧化氢（Ｈ２Ｏ２）等］一...     

植物生理学实验教学中H_2O_2可视化检测方法的改进

活性氧（reactive oxygen species,ROS）,如超氧阴离子自由基（O2-·）、羟自由基（·OH）和过氧化氢（H2O2）均是植物尤其是高等植物在有氧代谢过程中产生的,     

光系统Ⅱ颗粒内单线态氧诱导产生超氧阴离子自由基

活性氧是生物体有氧代谢的必然产物。当机体处于疾病或胁迫条件下 ,活性氧的生成将更加活跃[1] 。由于类囊体膜是植物体光合放氧的器官 ,处于高浓度的氧环境中 ,同时类囊体膜上还存在着活跃的电子传递体系 ,因此类囊体膜是超氧阴离子自由基生成的活跃部位[2 ] 。最近的研究表明 ,ＰＳⅠ和ＰＳⅡ都是超氧阴离子自由基的生成部位[3] 。其中 ,对ＰＳⅠ生成超氧的机制研究已比较深入[2 .4 ] ,而对ＰＳⅡ生成超氧阴离子自由基的机制研究是在近几年内刚刚开展[3 ,5- 7] 。ＰＳⅡ中生成的另一活性氧是单线态氧。通常认为由于强光照射下ＰＳⅡ生成的…     

超氧阴离子自由基对大鼠脑皮层神经细胞的损伤作用

为了探讨超氧阴离子自由基对神经细胞的影响,以产生超氧阴离子自由基系统（XO/X）作用于原代培养的新生大鼠大脑皮层神经元,分析神经细胞的生长状态、蛋白质被氧化修饰的程度、脂质过氧化程度、核DNA损伤程度、亚细胞结构变化以及Cu/ZnSOD基因表达等变化。结果显示：超氧阴离子自由基可使神经细胞的生长状态不佳,ATP酶活性降低为4.223μmol/(mg.min^-1)(Pr)。细胞总羰基含量增加为295.40μmol/g湿重,LPO含量增加为4.87mol/g(Pr),膜脂流动性下降（P值为0.398),核DNA单链断裂增加（DNA在SCG中的迁移率为7.35mm),亚细胞结构变化（线粒体肿胀和变性等）以及SOD基因表达增强（SOD含量、SOD活性和SODmRNA丰度均增加）。结果说明超氧阴离子自由基可损伤神经细胞的蛋白质、核酸、脂质和亚细胞结构。     

针叶树越冬针叶光氧化与叶绿体超氧阴离子自由基

以Tiron为自旋探针,检出了越冬针叶叶绿体指示超氧阴离子自由基产生的TH~·ESR信号。此信号可由紫外辐射,也可由光合有效辐射产生。以单位叶绿素量为基数计算的信号强度比已报道的其它植物材料大2～3个数量级。红松叶绿体信号又大于其它针叶树。此信号可被外源SOD,抗坏血酸、乙醇和N_2抑制;随光照增加而增强,12月到次年5月期间又随时间而增强。上述结果表明红松针叶的冬季光氧化伤害与叶绿体中过量超氧阴离子自由基的产生有关。     

超氧阴离子的产生及其在植物体内作用的研究

超氧阴离子自由基不仅是生物体内重要的自由基之一,也是所有活性氧自由基的前体。近年来许多文献报道生物体的一些重大疾病与超氧阴离子自由基关系密切,因此对超氧阴离子的研究具有非常重要的意义。本文综述了有关超氧阴离子自由基在生物体内及体外的产生、超氧阴离子对生物体的作用、超氧阴离子的检测方法、重点总结了超氧阴离子的产生及其在植物体内的作用。     

蒺藜内生真菌抗氧化活性菌株的筛选

为研究21株蒺藜内生真菌的抗氧化活性及筛选出一株抗氧化活性较好的菌株,本实验首先以总抗氧化能力为指标评价PDB培养基和察氏培养基发酵条件下所有菌株的抗氧化活性,选出总抗氧化能力都较强的前9株菌株测定其对DPPH·自由基、羟自由基和超氧阴离子自由基的清除作用,发现JL13、JL14和JL17菌株发酵产物的清除效果最为明显,因此对三株菌株发酵产物乙酸乙酯萃取部位清除自由基的活性进一步评价,结果显示:JL13菌株发酵产物清除DPPH·自由基、羟自由基和超氧阴离子自由基的能力都是最强的,ECs0依次为149.67、439.91和514.77μg/mL.该结果表明,蒺藜内生真菌具有较好的抗氧化潜力,具有一定的开发利用价值,尤其是JL13菌株,可以作为进一步实验研究的对象.     

迎春花色素提取及抗氧化性研究

目的:提取迎春花黄色素研究其抗氧化性能。方法:利用对羟基自由基(OH-·)和超氧阴离子自由基(O2-·)的清除能力研究迎春花色素的抗氧化性能。结果:随着迎春花色素量的增加,其清除OH-·和O2-·的能力逐渐提高,最高分别可达31.5%和91.0%。结论:迎春花色素对超氧阴离子和羟基自由基均具有较强的清除能力。     

三硝基甲苯中毒性白内障动物模型的建立及其发病机理的初步研究

反复多次给大鼠皮下注射20％三硝基甲苯(TNT)甘油:水混悬液,染毒15个月后21％动物发生白内障,其裂隙灯检查结果与人TNT性白内障基本相似,同时注射甘油:水溶剂的对照组大鼠无一例发生白内障。染毒10个月的大鼠,其晶状体LPO增高,GSH-P_X及GST活性降低,GR活性无变化,而GSH含量明显增加;注射TNT后肝脏LPO值、GSH含量、GSH-P_X、GR及GST活性均明显增高。本文结果提示,TNT中毒性白内障的形成可能系TNT及其代谢产物直接作用于晶状体,造成昌状体氧化损伤所致。TNT白内障大鼠模型的建立亦为深入探讨其发病机理及防治奠定了基础。     

硒拮抗超氧阴离子导致的心肌线粒体膜损伤

由黄嘌呤和黄嘌呤氧化酶体系产生的超氧阴离子作用于心肌线粒体后,其膜脂双层内产生了脂类自由基。在一定时间内,脂类自由基与自旋捕捉剂形成的加合物的ＥＳＲ信号强度随着孵育时间的增加而加强。１．０μｍｏｌ／Ｌ硒代蛋氨酸（Ｓｅ－Ｍｅｔ）或２．３μｍｏｌ／ＬｍＮａ２ＳｅＯ３可显著清除并抑制脂类自由基的产生。在的影响下,荧光探针ＤＰＨ在膜脂双层中的荧光寿合和膜脂流动性发生了明显改变。一定浓度的Ｓｅ－Ｍｅｔ或Ｎａ２ＳｅＯ３可明显拮抗的上述影响,前者的作用更为显著。     

Generation of alloxan free radicals in chemical and biological systems: implication in the diabetogenic action of alloxan

Electron spin resonance (ESR) studies that on reaction with NADPH, alloxan was reduced forming labile anion radicals giving a 7-line signal with g = 2.005. These radicals were also produced on incubation of alloxan with rat liver subcellular fractions and their production was greatly enhanced by NADPH. Alloxan effectively scavenged superoxide anion generated by a xanthine-xanthine oxidase (XOD) system in association with its reduction to these anion radicals. These radicals were also formed during incubation of alloxan with rat pancreatic beta-cells. These results suggest that the cytotoxicity of alloxan is related to the formation of alloxan anion radicals.     

巨噬细胞产生NO.和O_2~-自由基的分子机理

建立了用顺磁共振（ＥＳＲ）和化学发光技术测定巨噬细胞产生ＮＯ和氧自由基的方法．捕捉到了巨噬细胞受佛波酯刺激产生的ＮＯ．和Ｏ－２自由基．测定了在不同浓度Ｌ－精氨酸存在时佛波酯刺激后巨噬细胞产生的ＮＯ自由基．研究了巨噬细胞产生的ＮＯ和氧自由基的分子机理．结果表明巨噬细胞不仅产生氧自由基而且产生ＮＯ自由基．ＮＡＤＰＨ氧化酶产生氧自由基的部位位于巨噬细胞膜的外侧．ＮＯ合成酶活化产生ＮＯ自由基比ＮＡＤＰＨ氧化酶活化产生氧自由基晚几分钟．     

Effect of isorhapontigenin on respiratory burst of rat neutrophils

The effect of Isorhapontigenin (Iso) isolated from Belamcanda chinensis on respiratory burst of rat neutrophils was investigated. Iso (1, 10, 100 mmol/l) showed an inhibitory effect on superoxide anion and hydrogen peroxide production in phorbol myristate acetate (PMA) activated rat neutrophils in a concentration-dependent manner. Scanning electron microscopy detected that Iso (100 mmol/l) protected against surface changes in rat neutrophils stimulated with PMA. Also, 100 mmol/l Iso inhibited the release of beta-glucuronidase from the activated neutrophils. Electron-spin resonance (ESR) detected that Iso scavenged oxygen free radicals generated in the PMA activated Neutrophils. These results suggest that Iso inhibits respiratory burst of PMA-activated rat neutrophils by scavenging oxygen free radicals.     

Nitrobenzyl radical metabolites from microsomal reduction of nitrobenzyl chlorides

The o-, m-, and p-nitrobenzyl chlorides are reduced aerobically and anaerobically by NADPH and rat hepatic microsomes. Under aerobic conditions, these nitro anion radicals reduce oxygen to superoxide as demonstrated by oxygen consumption and spin trapping of superoxide with 5,5-dimethyl-1-pyrroline N-oxide. At low oxygen concentration, the p- and o-nitro anion radicals undergo intramolecular electron transfer and decompose to carbon-centered nitrobenzyl radicals, which can be spin-trapped with t-nitrosobutane. The p-nitrobenzyl (o-nitrobenzyl) radical adduct was characterized by a nitrogen hyperfine splitting of 16.5 G (17.1 G) and two equivalent beta-hydrogen hyperfine splittings of 10.6 G (14.4 G). The spin trap 5,5-dimethyl-1-pyrroline N-oxide also yields adducts characteristic of carbon-centered free radicals. This unimolecular decomposition is much faster than the disproportionation decay, which is characteristic of most nitro anion radicals, and the primary o- and p-nitrobenzyl chloride anion radicals never achieve detectable concentrations. The nitrobenzyl radical trapping is not inhibited by metyrapone or CO. In contrast, the m-nitrobenzyl anion radical does achieve a detectable steady-state concentration, which is increased 20% by either metyrapone or a CO atmosphere.     

The enzymatic one-electron reduction of porphyrins to their anion free radicals

The anaerobic enzymatic one-electron reduction of uroporphyrin I (in the absence of light) by the ferredoxin/ferredoxin:NADP+ oxidoreductase system was investigated using NADPH as the source of reducing equivalents. The porphyrin anion free radical metabolite formed by one-electron reduction of the parent molecule was detected with ESR spectroscopy. The ESR spectrum exhibited a singlet (g = 2.0021) with a 5.4-G peak-to-peak linewidth. The reduction process was also investigated under aerobic conditions. The reduction of molecular oxygen to superoxide anion radical by the porphyrin anion radical was demonstrated by using the ESR technique of spin trapping. The ESR spectra of the spin-trapped oxygen-derived radicals were superoxide dismutase-sensitive and catalase-insensitive, supporting the assignment of the trapped radical to the superoxide anion radical. These aerobic experiments demonstrate electron transfer from the porphyrin anion radical to molecular oxygen. The anaerobic reduction of Photofrin II by hepatic microsomes and the ferredoxin/ferredoxin:NADP+ oxidoreductase system to a porphyrin anion radical was also investigated. Free radical formation by ferredoxin: NADP+ oxidoreductase is totally dependent upon ferredoxin. The ESR spectrum of this porphyrin free radical also exhibited a singlet (g = 2.0026) with a 15-G peak-to-peak linewidth.     

Lymphocytes can produce respiratory burst and oxygen radicals as polymorphonuclear leukocytes.

The respiratory burst and production of oxygen radicals by lymphocytes stimulated with phorbol myristate acetate (PMA) was studied and compared with that of polymorphonuclear leukocytes (PMN) by electron paramagnetic resonance (EPR) and spin trapping technique. Superoxide anion and hydroxyl radicals spin adducts of DMPO were detected in the stimulated PMN system, but only hydroxyl radical spin adducts of DMPO were detected in the stimulated lymphocyte system. It was proved by superoxide dismutase (SOD) and catalase that the hydroxyl radicals produced in the stimulated lymphocyte system came from superoxide anions, just like the hydroxyl radicals produced in the stimulated PMN.     

Generation of radical anions of nitrofurantoin, misonidazole, and metronidazole by ascorbate

Nitrofurantoin, misonidazole, and metronidazole were reduced to their corresponding nitro anion radicals by ascorbate in anaerobic solutions at high pH. The nitrofurantoin anion radical could be detected at neutral pH. In neutral solutions, the nitro anion radicals of misonidazole and metronidazole were too unstable to be observed by electron spin resonance spectroscopy. At neutral pH, solutions containing ascorbate, nitrofurantoin, or misonidazole consumed oxygen. The addition of superoxide dismutase, catalase, or both superoxide dismutase and catalase decreased the rate of oxygen consumption. These results show that nitro anion radicals are formed by reduction with ascorbate, and superoxide anion radical and hydrogen peroxide are produced by reactions of these radicals with oxygen.     

慢性肾衰病人血清和红细胞抗氧化能力的ESR研究

用电子自旋共振(ESR)自旋捕集技术研究了正常人和肾衰病人血清和红细胞对黄嘌呤 黄嘌呤氧化酶体系产生的氧自由基的作用.结果发现:(1)正常人血清和红细胞能够有效地清除超氧阴离子自由基(O_2~-),而肾衰病人血清和红细胞清除O_2~-的能力明显比正常人血清和红细胞低;(2)正常人血清能有效地把黄嘌呤 黄嘌呤氧化酶体系产生的O_2~-转化为·OH,病人血清在这方面与正常人血清有显著性差异.     

An electron spin resonance study of oxyradical generation in superoxide dismutase- and catalase-deficient mutants of Escherichia coli K-12

The response of superoxide dismutase- and catalase-deficient strains of Escherichia coli to redox active compounds was examined by electron spin resonance. Levels of radicals formed in response to pyocyanine in situ were extremely low and were found to be predominantly extracellular, even in a strain completely deficient in both superoxide dismutase and catalase. In cell-free extracts of superoxide dismutase-minus strains incubated with NADPH and pyocyanine, the primary accumulating radical was the superoxide anion (O2-), although low levels of the hydroxyl radical (.OH) were also detected. In contrast, extracts from strains lacking catalase were found to accumulate higher levels of hydroxyl radicals.     

Evaluation of electron spin resonance for studies of superoxide anion production by human neutrophils interacting with Staphylococcus aureus and Staphylococcus epidermidis

The present study evaluates electron spin resonance (ESR) and the spin trapper 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) for analysis of superoxide radical production by human neutrophils interacting with viable Staphylococcus aureus and Staphylococcus epidermidis bacteria. To avoid auto-activation due to interaction with glass surfaces, neutrophils were preincubated in plastic tubes until the peak response was reached, and then transferred to a quartz flat cell to record the ESR spectra. The time point for peak response was identified by parallel analysis of the bacteria–neutrophil interaction using luminol amplified chemiluminescence. We found detectable ESR spectra from neutrophils interacting with as few as five bacteria of the weak activating S. epidermidis per neutrophil. Addition of the NADPH oxidase inhibitor diphenylene iodonium totally abolished spectra. Catalase, DMSO or an iron chelator had no impact on the produced spectra and ionomycin, a selective activator of intracellular NADPH oxidase, gave significant ESR spectra. Taken together, our results indicate that DEPMPO is cell permeable and detects NADPH oxidase derived superoxide anions formed in phagosomes or released by human neutrophils phagocytosing viable S. aureus and S. epidermidis. The technique may be used as a sensitive tool to evaluate superoxide anion production in human neutrophils.