亚油酸体系脂质过氧化引起的DNA损伤研究

用含两个双键的不饱和脂肪酸-亚油酸作为模型化合物,分析其过氧化程度,同时检测了由于脂质过氧化而引起的DNA损伤,结果表明:在脂质过氧化过程中,DNA与亚油酸过氧化产物反应生成一种荧光物质、其最大激发波长315nm最大发射波长410nm并随着氧化时间增加而增加,与此同时,双链DNA百分含量明显下降,DNA-溴乙锭复合物荧光显著降低,反映了DNA二级结构受到破坏.上述结果揭示了脂质过氧化产物在自由基引起DNA的损伤中可能起重要作用     

脂质体过氧化对DNA的损伤研究

研究了以脂质体为材料的脂质过氧化引起的ＥＮＡ损伤,同时检测了脂质过氧化程度与ＤＮＡ受损情况。结果表明：在脂质体过氧化程度中,ＤＮＡ的增色效应,对核酸酶的敏感程度,ＤＮＡ双链百分含量和ＤＮＡ－溴乙锭复合物的荧光强度随着氧化时间的增加而降低。在四种碱基中,鸟嘌呤损伤最严重。多种自由基清除列实验表明：脂质过氧化所产生的羟基自由基和单线态氧可能是引起ＤＮＡ氧化损伤的重要因素。     

天然抗氧化剂丹参酮Ⅱ—A对肝细胞脂质过氧化产物与DNA相互作用的影响

［３Ｈ］花生四烯酸标记的肝细胞,经ＦｅＣｌ２－ＤＴＰＡ启动脂质过氧化后,细胞ＤＮＡ出现放射性,并随保温时间增加而逐渐增高,表明在细胞内脂质过氧化产物与ＤＮＡ发生相互作用,生成了一种ＤＮＡ加成物,经测定它具有特征荧光光谱,显示较低的增色效应和Ｔｍ值。用高度敏度荧光图象显微镜直接观察发现丹参酮Ⅱ－Ａ经细胞摄取后主要滞留在细胞膜与胞浆中。它能有效地抑制细胞脂质过氧化,减少脂质－ＤＮＡ加成物的产生,并阻止了细胞存活率和Ｏ６甲基鸟嘌呤转移酶活性的降低,其抑制率与ＶｉｔＥ,ＢＨＴ相近,但显著高于ＮａＮ３,甘露醇和ＳＯＤ。上述结果提示丹参酮Ⅱ－Ａ是一种新的有效的细胞内脂质过氧化产物与ＤＮＡ相互作用的抑制剂。它对ＤＮＡ的保护作用可能是通过清除脂类自由基而阻断脂质过氧化的链式反应,抑制ＤＮＡ加成物的生成,从而减少了细胞毒性。     

大鼠肝细胞核膜脂质过氧化对核DNA影响的研究

采用大鼠肝脏细胞核为材料,研究了核膜脂质过氧化对核ＤＮＡ的影响。证实核膜脂质过氧化可以引起ＤＮＡ损伤,表现为ＤＮＡ的增色效应、熔解温度、从ＤＮＡ向ＥＢ的能量转移效率降低,圆二色谱发生显著变化。另外受损ＤＮＡ对ＤＮａｓｅⅠ产生明显抗性和琼脂糖凝胶电泳结果提示核膜脂质过氧化引起的ＤＮＡ损伤可能以交联为主,同时利用原子力显微镜（ＡＦＭ）直接观察到了交联ＤＮＡ的生成。各种自由基清除剂对ＤＮＡ损伤保护的差异说明脂类自由基可能在活性氧自由基引起的ＤＮＡ损伤中具有重要作用。     

DNA与红细胞膜脂质过氧化相互作用研究

研究了ＤＮＡ与红细胞膜脂质过氧化产物的相互作用。与无ＤＮＡ的反应体系相比,ＤＮＡ的加入明显增加４４０ｎｍ处的荧光强度,这种效应是由于ＤＮＡ与过氧红细胞膜生成了新的荧光物质,其激发波长３１５ｎｍ,发射波长４１０ｎｍ．维生素Ｅ强烈抑制荧光产物的形成。ＤＮＡ经分离、纯化后用ＥＢ作荧光探针研究表明,ＤＮＡ二级结构发生了改变,ＤＮＡ—ＥＢ复合物荧光光谱,ＤＮＡ—ＥＢ复合物之间的能量转移效率均有明显变化。同时证实ＤＮＡ损伤具有碱基特异性,即主要是鸟嘌呤受到损伤。     

天然抗氧化剂丹参酮Ⅱ—A对肝细胞脂质过氧化产物与DNA相互作用的影响

［＾３Ｈ］花生四烯酸标记的肝细胞,经ＦｅＣｌ２－ＤＴＰＡ启动脂质过氧化后,细胞ＤＮＡ出现放射性,并随保温时间增加而逐渐增高,表明在细胞内脂质过氧化产物与ＤＮＡ发生相互作用,生成了一种ＤＮＡ加成物,经测定它具有特征荧光光谱,显示较低的增色效应和Ｔｍ值。用高度敏度荧光图象显微镜直接观察发现丹参酮Ⅱ－Ａ经细胞摄取后主要滞留在细胞膜与胞浆中。它能有效地抑制细胞脂质过氧化,减少脂质－ＤＮＡ加成物的产生,并阻     

川芎嗪对肝缺血/再灌注损伤脂质过氧化的影响

目的：观察肝缺血／再灌注损伤时脂质过氧化的动态变化和川芎嗪的影响,并探讨其机制。方法：健康家兔20只,复制肝缺血／再灌注损伤模型。随机分为对照组（n=10）和川芎嗪组（n=10）。连续观察缺血前,缺血25min、再灌注25min、60min和120min时血浆中黄嘌呤氧化酶（XO）活性、超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量和谷丙转氨酶（GPT）活性的动态变化及川芎嗪对不同时限上述指标的影响。结果：川芎嗪组的XO、SOD、MDA和GPT在再灌注的各时限与对照组比较均有显著或非常显著差异（P＜0．05或P＜0．01）。结论：川芎嗪能通过抑制氧自由基的生成,增强氧自由基的清除,对肝缺血／再灌注损伤起着良好的抗脂质过氧化作用。     

营养缺乏与脂质过氧化的关系

人体必需的营养素如含硫氨基酸、维生素A、B_2、C、E、辅酶Q等以及微量元素铜、锌、锰、硒等均有抗氧化作用;果糖能加重脂质过氧化作用,葡萄糖或淀粉则有减轻脂质过氧化作用。这些抗氧化营养素缺乏时,机体抗氧化能力下降,多不饱和脂肪酸发生脂质过氧化而导致组织、细胞等损害。因此,在治疗这些营养缺乏病时,不仅要补给所缺乏的营养素,而且还要给予其他抗氧化剂,以协同作用,取得较好的治疗效果。     

Ascorbic Acid Inhibits Lipid Peroxidation but Enhances DNA Damage in Rat Liver Nuclei Incubated with Iron Ions

In this report we studied DNA damage and lipid peroxidation in rat liver nuclei incubated with iron ions for up to 2 hrs in order to examine whether nuclear DNA damage was dependent on membrane lipid peroxidation. Lipid peroxidation was measured as thio-barbituric acid-reactive substances (TBARS) and DNA damage was measured as 8-OH-deoxyguanosine (8-OH-dG). We showed that Fe(II) induced nuclear lipid peroxidation dose-dependently but only the highest concentration (1.0 mM) used induced appreciable 8-OH-dG. Fe(II1) up to 1 mM induced minimal lipid peroxidation and negligible amounts of 8-OH-dG. Ascorbic acid enhanced Fe(II)-induced lipid peroxidation at a ratio to Fe(II) of 1:l but strongly inhibited peroxidation at ratios of 2.5:l and 5:l. By contrast, ascorbate markedly enhanced DNA damage at all ratios tested and in a concentration-dependent manner. The nuclear DNA damage induced by 1 niM FeSO₄/5 mM ascorbic acid was largely inhibited by iron chelators and by dimethylsulphoxide and manni-tol, indicating the involvement of OH. Hydrogen peroxide and superoxide anions were also involved, as DNA damage was partially inhibited by catalase and, to a lesser extent, by superoxide dismutase. The chain-breaking antioxidants butylated hydroxytoluene and diphenylamine (an alkoxyl radical scavenger) did not inhibit DNA damage. Hence, this study demonstrated that ascorbic acid enhanced Fe(II)-induced DNA base modification which was not dependent on lipid peroxidation in rat liver nuclei.     

Lipid peroxide induced DNA damage: protection by turmeric (Curcuma longa)

Summary Liposomal lipid peroxidation and peroxide induced DNA damage were investigated. Inhibition of lipid peroxidation was studied using 400 µM uric acid, -carotene, -tocopherol, curcumin and butylated hydroxyanisole (BHA). Curcumin, the active principle of turmeric (Curcuma longa), was as effective an antioxidant as BHA. An aqueous extract of turmeric was also found to be an effective inhibitor. The inhibition obtained using this aqueous extract, incorporated into the liposome itself, was 70% at 300 ng/µ1 This indicates the presence of yet another antioxidant in turmeric besides the lipophilic curcumin. The aqueous antioxidant extended 80% protection to DNA against peroxidative injury at 100 ng/µl. This component of turmeric is being characterised and investigated as an antioxidant/anticlastogen and as an antipromoter.Abbreviations GT₁b Trisialoganglioside - TBS Tris Buffered Saline - PBS Phosphate Buffered Saline - TBA Thio Barbituric acid - BHA Butylated Hydroxy Anisole - EDTA Ethylene Diamine Tetra Acetic Acid     

Catalases CAT1 and CAT3 Are not Key Enzymes in Alleviating Gamma Irradiation-Induced DNA Damage,H2O2 Accumulation,or Lipid Peroxidation in Arabidopsis thaliana

Gamma irradiation increased catalase activities at 0.1 kGy and decreased them at 10 kGy in Arabidopsis wild type and catalase-deficient mutants, cat3-1 and cat1 cat3. Irradiation induced DNA damage, H₂O₂ accumulation, and lipid peroxidation in both mutants as well as the wild type. Thus catalases might not be key enzymes protecting gamma irradiation-induced damage.     

Non-Enzymic Lipid Peroxidation in Microsomes and Microsomal Phospholipids Induced by Anthracyclines

The stimulation of non-enzymic lipid peroxidation by doxorubicin, daunorubicin and 7 derivatives was investigated in extracted microsomal phospholipids and in intact microsomes.

Evidence was obtained for the necessity of a free amino-sugar moiety for a stimulative effect on lipid peroxidation. Binding of anthracyclines to RNA (which is present in microsomes) was inhibitory towards stimulation.

Drugs that stimulated lipid peroxidation in a non-enzymic system with extracted phospholipids also were stimulative in an enzymic, NADPH-dependent, microsomal system. They were not always effective in intact microsomes without the enzymic system.

The role of the enzymic system in the stimulation of anthracycline induced lipid peroxidation is thought to be the reduction of iron ions rather than the stimulation of oxygen radical production via the anthracyclines.     

Lipid Peroxidation In Vivo Induced by Reversible Global Ischemia in Rat Brain

It has been hypothesized that ischemia, followed by reperfusion, facilitates peroxidative free-radical chain processes in brain. To resolve this question, rats were subjected to reversible global ischemia. From coronal sections of brains frozen in situ, small (ca. 2 mg) amounts of tissue were sampled from neocortex, hippocampus, and thalamus of both cerebral hemispheres of four groups of rats exposed to 30 min cerebral ischemia followed by 0, 30, 60, and 240 min of reperfusion, and from a control group subjected to the same operative procedures, except for the induction of ischemia. Heptane-solubilized total lipid extracts from these samples were analyzed spectroscopically in the 190-330 nm range for content of isolated (nonconjugated) double bonds and of conjugated diene structures; the latter are formed from isolated double bonds during peroxidation of unsaturated fatty acids. Spectra derived from tissue regions of rats subjected to ischemia, or ischemia followed by reperfusion, were compared to averaged, region-specific control spectra and were normalized to the original content of isolated double bonds in the peroxidized samples. The resultant difference spectra were analyzed in terms of ratios of conjugated diene concentration to the concentration of isolated double bonds originally at risk in the specific tissue zones considered. The peak representing conjugated diene formation was centered at 238 +/- 1 nm and was usually well resolved when the molar ratio [conjugated diene]/[isolated double bonds], expressed as a percentage [( CD]/[IDB]), was greater than 0.25%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Non-Enzymic Lipid Peroxidation in Microsomes and Microsomal Phospholipids Induced by Anthracyclines

The stimulation of non-enzymic lipid peroxidation by doxorubicin, daunorubicin and 7 derivatives was investigated in extracted microsomal phospholipids and in intact microsomes.

Evidence was obtained for the necessity of a free amino-sugar moiety for a stimulative effect on lipid peroxidation. Binding of anthracyclines to RNA (which is present in microsomes) was inhibitory towards stimulation.

Drugs that stimulated lipid peroxidation in a non-enzymic system with extracted phospholipids also were stimulative in an enzymic, NADPH-dependent, microsomal system. They were not always effective in intact microsomes without the enzymic system.

The role of the enzymic system in the stimulation of anthracycline induced lipid peroxidation is thought to be the reduction of iron ions rather than the stimulation of oxygen radical production via the anthracyclines.     

Investigation of Lipid Peroxidation in Human Low Density Lipoprotein

Human plasma low density lipoprotein (LDL) exposed to oxygen saturated buffer becomes depleted of alpha-tocopherol within 3 to 6 hours. Thereafter, lipid peroxidation commences as evidenced by the loss of 18:2 (67nmol/mg LDL) and 20:4 (12nmol/mg LDL) and the concomitant formation of 4-hydroxy-nonenal (0.28 nmol/mg LDL) and fluorescent compounds. The major fluorophor in apo B of oxidized LDL has an excitation maximum at 355 nm and an emission maximum at 430 nm. A fluorophor with the same spectral properties is produced in apo B, if LDL is incubated with 4-hydroxynonenal, whereas malonal-dehyde gives a fluorophor with excitation and emission maxima at 400/470nm. Three-dimensional fluorescence spcetroscopy proved to be an useful tool in analysing the complex fluorescence of apo B.     

二氧化硫吸入对小鼠脑组织的氧化损伤

对昆明小鼠进行不同浓度SO2 吸入试验 ,然后测定脑组织中还原型谷胱甘肽 (GSH)含量、谷胱甘肽过氧化物酶 (GSH Px)活性、超氧化物歧化酶 (SOD)活性及脂质过氧化产物丙二醛 (MDA)含量 ,研究SO2 对小鼠中枢神经系统的氧化损伤作用 .雄鼠脑组织匀浆上清液GSH含量在SO2 浓度为 14mg m3 时明显上升 (P <0 0 5 ) ,浓度为 2 8、5 6和 84mg m3 时极显著降低 (P <0 0 1) ,而雌鼠在14和 2 8mg m3 时无明显变化 (P >0 0 5 ) ,在 5 6和 84mg m3 时极显著降低 (P <0 0 1) .雌雄小鼠的GSH Px活性在 14和 2 8mg m3 时无明显变化 (P >0 0 5 ) ,在 5 6、84mg m3 时均极显著降低 (P <0 0 1,P <0 0 0 1) .在SO2 上述 4种吸入浓度下 ,雌雄小鼠的SOD活性均显著降低 (P <0 0 5 )或极显著降低 (P <0 0 1,P <0 0 0 1) ;雄鼠和雌鼠的脂质过氧化产物丙二醛 (MDA)含量均极显著增高 (P <0 0 1,P <0 0 0 1) .结果表明 ,小鼠脑组织对SO2 的氧化损伤作用非常敏感 ,是SO2 的靶器官之一 ,SO2 的污染可能与某些脑疾患有关     

Lipid Peroxidation Induced ByN-Nitrosodimethylamine (Ndma) In Rats In Vivo and in Isolated Hepatocytes

To investigate the role of carcinogenic chemicals as a possible cause for oxidative damage, rats were treated with jV-nitrosodimethylamine (NDMA) and various measures of lipid peroxidation were followed. As an indication of enhanced peroxidative processes in vivo NMDA treatment produced rapidly an increase in the rate of ethane exhalation. A single i.p. or p.o. injection of lOmg/kg b.w. elevated ethane exhalation by 13-14 fold; a single dose of 0.5mg/kg of NDMA (the smallest dose tested) increased 5-fold the amount of ethane exhaled. Similarly, lipid peroxidation in the liver of NDMA-treated rats (measured by diene conjugation, chemiluminescence, the production of fluorescent and TBA-reactive material) was found to be increased rapidly showing a peak already 20min after dosing. Simultaneously, NDMA-treatment slightly decreased antioxidant enzyme activities and GSH contents in the liver. In isolated rat hepatocytes the lucigenin-dependent chemiluminescence, as well as H,0₂ release, were increased by micromolar concentrations of NDMA. Finally, it was shown that the rate of NADPH-stimulated ethane production by hepatic microsomes, prepared from untreated rats, was increased in the presence of NDMA. Thus, our results demonstrate that the alkylating NDMA can induce oxidative stress in rodents. Whether the same is true for other classes of carcinogens and processes known to affect tumor initiation/progression is presently under investigation.     

Lipid Peroxidation Scavengers Prevent the Carbonylation of Cytoskeletal Brain Proteins Induced by Glutathione Depletion

In this study, we investigated the possible link between lipid peroxidation (LPO) and the formation of protein carbonyls (PCOs) during depletion of brain glutathione (GSH). To this end, rat brain slices were incubated with the GSH depletor diethyl maleate (DEM) in the absence or presence of classical LPO scavengers: trolox, caffeic acid phenethyl ester (CAPE), and butylated hydroxytoluene (BHT). All three scavengers reduced DEM-induced lipid oxidation and protein carbonylation, suggesting that intermediates/products of the LPO pathway such as lipid hydroperoxides, 4-hydroxynonenal and/or malondialdehyde are involved in the process. Additional in vitro experiments revealed that, among these products, lipid hydroperoxides are most likely responsible for protein oxidation. Interestingly, BHT prevented the carbonylation of cytoskeletal proteins but not that of soluble proteins, suggesting the existence of different mechanisms of PCO formation during GSH depletion. In pull-down experiments, beta-actin and alpha/beta-tubulin were identified as major carbonylation targets during GSH depletion, although other cytoskeletal proteins such as neurofilament proteins and glial fibrillary acidic protein were also carbonylated. These findings may be important in the context of neurological disorders that exhibit decreased GSH levels and increased protein carbonylation such as Parkinson's disease, Alzheimer's disease, and multiple sclerosis.