维生素E和β胡萝卜素对巨噬细胞氧化修饰低密度脂蛋白的影响

目的 :　研究维生素 E(VE)、β胡萝卜素 (βC)对巨噬细胞 (MΦ )介导的低密度脂蛋白 (LDL)氧化修饰能力的影响。方法 :　于培养成熟的 MΦ中分别加入不同剂量的 VE(40、1 0 0、2 0 0 μmol/L)和 βC(0 .5、1 .0、2 .0 μmol/L) 37℃孵育 2 4 h,通过测定培养物上清液中硫代巴比妥酸反应物 (TBARS)、荧光物质 (Lipofusin)、LDL电泳迁移率 (Rf)及共轭二烯 (Dienes)的形成 ,反映LDL的氧化修饰程度。结果 :　体外补充 VE可以显著降低培养物上清液中 TBARS、荧光物质以及共轭二烯的形成 ,明显抑制 LDL的电泳迁移率 ,随剂量增大作用加强 ;βC低剂量组 (0 .5μmol/L)可显著降低培养物上清液中 TBARS、荧光物质以及共轭二烯的形成 ,明显抑制 LDL的电泳迁移率 ,其余各组无明显影响。结论 :　 VE、βC均可抑制 MΦ介导 LDL氧化修饰的能力 ,并具一定的量效关系 ,提示在 MΦ氧化修饰 LDL的可调节因子中 ,抗氧化营养素是一种有效措施     

不同水平维生素E和β-胡萝卜素对Cu~(2 )氧化修饰低密度脂蛋白的影响

研究不同浓度的维生素 E(VE)和β-胡萝卜素 (βC)对 Cu2 诱导的氧化修饰低密度脂蛋白 (L DL )作用的影响 ,通过测定硫代巴比妥酸反应物质 (TBARS)、L DL 的电泳迁移率 (Rf)以及荧光物质 (L ipofusin)扫描 ,反映 L DL的氧化修饰程度。结果表明 :VE、βC均可减少 TBARS的产生、减小 L DL的 Rf,并且具有剂量 -效应关系 ,随浓度增加 ,VE抑制作用加强而 βC抑制作用减弱 ,而且 VE对 TBARS的影响比 βC小 ,对 Rf的影响比βC大。二者对荧光物质均有降低作用 ,但无剂量 -效应关系。提示 VE、βC均可不同程度的抑制Cu2 氧化修饰 L DL 的作用 ,在降低机体脂质过氧化反应、减少氧化修饰型 L DL(OX- L DL)的形成方面具有重要作用 ,但二者作用机理可能并不相同     

维生素C对肺泡巨噬细胞脂质过氧化及抗氧化酶的影响

目的 探讨维生素C拮抗镍所致细胞毒作用及作用机理。方法 采用体外细胞培养方法，观察维生素C对染镍肺泡巨噬细胞包膜脂质过氧化产物丙二醛（MDA）及超氧化物歧化酶（SOD）活性的影响。结果 在体外染镍肺泡巨噬细胞培养过程中加入不同浓度维生素C（25，50和100μmol/L）可提高肺泡噬细胞间SOD活性，具剂量反应关系。维生素C能显著抑制MDA生成量，其中以50和100μmol/L浓度组作用最为明显。结论 镍可致细胞脂质过氧化，维生素C具有拮抗镍所致细胞毒性的作用，可能与其抗氧化功能有关。     

低水平大豆异黄酮对血清脂蛋白氧化修饰的影响

目的 :　评价低水平 (0 .5～ 1 0μmol/L)大豆异黄酮组分 (染料木素、大豆素和染料木甙 )对血清脂蛋白氧化修饰过程作用的效果及其特点。方法 :　采用 Cu2 +诱导全血清脂蛋白氧化修饰模型 ,通过检测体系中共轭双烯和硫代巴比妥酸反应物质 (TBARS)生成量变化反映异黄酮组分对脂蛋白氧化修饰过程和结局的影响。结果 :　启动氧化前向血清脂蛋白体系中加入 0 .5～1 0 μmol/L的染料木素、大豆素或染料木甙和 α-生育酚均显著减少共轭双烯和 TBARS的生成 ,并存在剂量相关关系。当血清脂蛋白氧化启动后 ,加入 1 0μmol/L异黄酮组分仍显示有较强的抑制作用 ,只是作用强度比启动前加入时减弱 ;而相同浓度的α-生育酚仅对共轭双烯生成显示有一定抑制作用 ,对 TBARS生成甚至呈现促进趋势。结论 :　低水平异黄酮组分即能对血清脂蛋白氧化修饰产生抑制作用 ,且在氧化启动后的效果优于 α-生育酚     

β-胡萝卜素对染镍肺泡巨噬细胞MDA及SOD的影响

目的：探讨β－胡萝卜素拮抗三氧化二镍的细胞毒作用及其机理，方法：采用体外细胞培养方法，观察β－胡萝卜素对染镍肺泡巨噬细胞膜脂质过氧化产物丙二醛（MDA）及超氧化物歧化酶（SOD）活性的影响。结果：在体外染镍肺泡巨噬细胞培养过程中加入不同浓度β－胡萝卜素（25，50和100μmol/L）可提高肺泡巨噬细胞内SOD活性，呈剂量－反应关系，维生素E能显抑制MDA生成量，其中以50μmol/L和100μmol/L浓度组作用最为明显，结论：镍可致细胞脂质过氧化，β－胡萝卜素具有拮抗镍所致细胞毒性的作用，可能与其抗氧化功能有关。     

邻苯二甲酸二丁酯对小鼠腹腔巨噬细胞的影响

目的研究邻苯二甲酸二丁酯(dibutyl phthalate,DBP)对小鼠腹腔巨噬细胞的影响。方法昆明雌性小鼠腹腔巨噬细胞,经6种不同浓度(0、6.25、12.5、25、50、100μmol/L)的DBP分别暴露12、24 h后,观察细胞形态学变化,测定细胞活性(CCK-8)、乳酸脱氢酶(LDH)、活性氧(ROS)及丙二醛(MDA)水平,观察50μmol/L维生素E(vitamin E,VE)对100μmol/L DBP所致氧化损伤的拮抗。结果随着DBP暴露剂量的增加,较高剂量的DBP(≥25μmol/L)可使小鼠巨噬细胞产生过量的ROS(P0.01),MDA含量明显上升(P0.01),同时伴有小鼠巨噬细胞的CCK-8含量下降(P0.01)及LDH释放增加(P0.01);与100μmol/L DBP组比较,100μmol/L DBP+50μmol/L VE组CCK-8含量上升,LDH、ROS及MDA水平均明显下降(P0.01)。结论结果表明,较高剂量(≥25μmol/L)的DBP可引起小鼠腹腔巨噬细胞的氧化损伤,致巨噬细胞活性降低和细胞膜破坏;维生素E作为抗氧化剂,在一定程度上可拮抗DBP造成的巨噬细胞损伤。     

镁对人体低密度脂蛋白氧化修饰的影响

目的 :　观察镁对人体低密度脂蛋白 (LDL)氧化修饰的影响。方法 :　一次性密度梯度超速离心法制备人天然 LDL,共轭二烯法检测 Mg2 +对 Cu2 +介导的 LDL氧化反应敏感性的影响 ,硫代巴比妥酸反应物 (TBARS)法检测 Mg2 +对 Cu2 +和内皮细胞介导的 LDL氧化修饰程度的影响。结果 :　 1 .LDL+Cu2 + +Mg2 +各剂量组 LDL氧化反应潜伏期较 LDL+Cu2 +组明显延长 ;2 .LDL+Cu2 + +0 .3mmol/L Mg2 +组和 LDL+Cu2 + +0 .6mmol/L Mg2 +组 TBARS低于 LDL+Cu2 + 组 ,P<0 .0 1 ;3.在内皮细胞介导的 LDL氧化体系中 ,补 Mg2 + 各剂量组 TBARS低于空白对照组 ,LDL+Mg2 +各剂量组 TBARS低于 LDL组 ,差异均具有显著性 (P<0 .0 5)。结论 :　在一定实验条件下 Mg2 +可阻断 LDL的氧化反应     

不同水平维生素E和β—胡萝卜素对Cu^2＋氧化修饰低密度脂蛋白的影响

研究不同浓度的维生素Ｅ（ＶＥ）和β－胡萝卜素（βＣ）对Ｃｕ＾２＋诱导的氧化修饰低密度脂蛋白（ＬＤＬ）作用的影响,通过测定硫代巴比妥酸反应物质（ＴＢＡＲＳ）、ＬＤＬ的电泳迁移率（Ｒｆ?以及荧光物质（Ｌｉｐｏｆｕｓｉｎ）扫描,反映ＬＤＬ的氧化修饰程度。结果表明：ＶＥ、βＣ均可减少ＴＢＡＲＳ的产生、减小ＬＤＬ的Ｒｆ,并且具有剂量－效应关系,随浓度增加,ＶＥ抑制作用加强而βＣ抑制作用减弱,而且ＶＥ对ＴＢＡ     

氧化型低密度脂蛋白对血管平滑肌细胞应激活化蛋白激酶活性及凋亡的影响

目的 观察氧化型低密度脂蛋白（Ox－LDL）对血管平滑肌细胞凋亡及应激活化蛋白激酶（SAPK）活性的影响。方法 采用3个时间水平（24、48、72h）、4个剂量水平（0、50、100、200μg/ml）的两因素析因设计观察Ox-LDL对兔主动脉血管平滑肌细胞（vascular smooth muscle cells,VSMCs）凋亡影响的时间、剂量效应关系；Ox－LDL对兔主动脉血管平滑肌细胞SAPK活性影响。结果 Ox-LDL诱导VSMCs凋亡随时间和剂量升高而不断增加，呈现一定的时间、剂量效应关系（P＜0．01）；Ox－LDL可引起各血管平滑肌细胞SAPK活性升高。结论 Ox－LDL诱导血管平滑肌细胞凋亡与其作用浓度、时间相关；SAPK信号通路可能在Ox－LDL诱导的血管平滑肌细胞凋亡过程中起重要的信号转导作用。     

氢醌/Cu2+对小鼠骨髓细胞线粒体氧化损伤的研究

目的 研究在Cu^2 存在的条件下,氢醌（HQ）对小鼠骨髓细胞线粒体的氧化损伤。方法 染毒：（1）在1μmol/LCu^2 存在的条件下,小鼠骨髓细胞用0、10、20和40μmol/LHQ染毒30min;（2）1μmol/LCu^2 存在的条件下,20μmol/LHQ染毒30、60、120min。观察骨髓细胞死亡率（CDR）、活性氧（ROD）生成、线粒体酶活力和线粒体电位（MMP）的改变。结果 在1μmol/LCu^2 存在的条件,HQ正最低剂量组（10μmol/L)和最染毒时间（30min,20μmol/L）即表现出ROS生成增加（为对照组的374％和541％）、CDR增加（为对照组的115％和117％）、线粒体酶活力下降（为对照组的54％和30％）和存在剂量、时间的依赖关系（ROS：r=0.941,r=-0.981;CDR:r=0.886,r=0.886;线粒体酶活力：r=-0.842,r=-0.902;MMP：r=-0.844,r=-0.961),ROS生成与MMP、CDR和线粒体酶活力间相关密切（r分别为－0。902,0。943,－0。977）。结论 在Cu^2 存在的情况下,HQ可导致小鼠骨髓细胞线粒体氧化损伤。细胞内ROS生成增加致线粒体氧化损伤可能是HQ诱导小鼠骨髓细胞毒性的重要途径之一。     

Vitamin C inhibits lipid oxidation in human HDL

HDL are susceptible to oxidation, which affects their cardioprotective properties. Although several studies have reported inhibition of HDL oxidation by vitamin E, none has determined the potential protective effect of vitamin C, another important blood antioxidant. We investigated whether vitamin C protects HDL from oxidation by incubating HDL (0.2 g of protein/L) at 37 degrees C with cupric (Cu2+) ions (10 micromol/L) in the absence (control) or presence of vitamin C (20-200 micromol/L). In the absence of vitamin C, lipid oxidation in HDL began immediately and proceeded rapidly. Cholesteryl linoleate declined to a minimum, whereas lipid oxidation products (lipid dienes and TBARS) increased to near-maximal levels within 1 h. Vitamin C (50-200 micromol/L) retarded initiation of lipid oxidation for at least 4 h under the same conditions. The ability of vitamin C to preserve the cardioprotective antioxidant function of HDL was also assessed. HDL (0.5 g of protein/L) preincubated with Cu2+ (10 micromol/L) for 2 h in the absence of vitamin C lost antioxidant activity (45.4 +/- 6.2% inhibition of LDL oxidation compared with 93.2 +/- 3.6% for native HDL, P < 0.05). The addition of vitamin C (50-200 micromol/L) during preincubation of HDL with Cu2+, however, resulted in no significant loss of HDL antioxidant activity (77.3 +/- 0.3 to 89.8 +/- 5.4% inhibition of LDL oxidation, P > 0.05 compared with native HDL). Our results demonstrate that vitamin C inhibits lipid oxidation in HDL and preserves the antioxidant activity associated with this lipoprotein fraction.     

Alpha-tocopherol distribution in lipoproteins and anti-inflammatory effects differ between CHD-patients and healthy subjects

OBJECTIVE: The purpose of this study was to investigate the dose-dependent effects of RRR-alpha-tocopherol supplementation in coronary heart disease (CHD) patients and healthy subjects on plasma alpha-tocopherol levels, plasma lipoprotein distribution, LDL oxidation, and inflammatory plasma markers. METHODS: 12 patients with coronary heart disease and 12 healthy subjects were supplemented with increasing dosages of RRR-alpha-tocopherol at 100, 200 and 400 mg/day for a period of 3 weeks per dose. Lipoproteins were separated by FPLC and ultracentrifugation. Alpha-tocopherol was measured by HPLC. Resistance of LDL to oxidation was determined by reading the absorption at 234 nm after CuCl2-induced oxidation. Clinical chemistry and inflammatory markers were measured on automated analysis systems. RESULTS: Plasma alpha-tocopherol concentrations at baseline were comparable between CHD-patients and healthy subjects (21.7 +/- 4.7 micromol/L and 25.8 +/- 7.6 micromol/L, respectively). CHD-patients showed a significant increase (59%) of plasma alpha-tocopherol concentrations to 34.6 +/- 9.8 micromol/L at a dosage of 100 mg/day RRR-alpha-tocopherol, whereas healthy subjects showed a significant (54%) increase to 39.7 +/- 6.1 micromol/L only with 400 mg/day RRR-alpha-tocopherol. In addition, CHD-patients showed a significantly increased enrichment of alpha-tocopherol in VLDL. Supplementation (200 mg/day) caused a significant decrease of the acute phase plasma proteins C-reactive protein (CRP) (-65%) and fibrinogen (-24%). CONCLUSION: Our data demonstrate that CHD-patients require lower dosages of alpha-tocopherol supplementation than healthy subjects to exert biological effects on plasma lipoproteins and acute phase response.     

镁对氧化低密度脂蛋白致内皮细胞损伤的保护作用

为探讨镁对内皮细胞的保护作用 ,用一次性密度梯度超速离心法制备人低密度脂蛋白 (LDL) ,以共轭二烯法和改良八木法检测Mg2 +(0 3、0 6、1 2和 2 4mmol L)对Cu2 +介导LDL氧化反应潜伏期和氧化修饰程度的影响。另将传至 2～ 3代的人脐静脉内皮细胞分为正常对照组、ox LDL对照组、补镁组和ox LDL +Mg2 +组 ,改良八木法测定细胞脂质过氧化物水平 ,黄嘌呤氧化法测定细胞外SOD活性 ,DTNB法测定含硒和不含硒GSH Px活性。结果显示 ,(1)Mg2 +各剂量组明显延长Cu2 +介导LDL氧化反应潜伏期 ,0 3和 0 6mmol LMg2 +显著降低TBARS的生成 ;(2 )与ox LDL组相比 ,ox LDL +Mg2 +各剂量组TBARS生成量显著下降 ,SOD活性显著升高 ,含硒GSH Px酶活力显著升高 ,不含硒GSH Px活力显著升高。提示镁抑制LDL的氧化修饰 ,补镁能降低细胞脂质过氧化物水平 ,增强抗氧化酶的的活性     

Dietary supplementation with vitamins C and E inhibits in vitro oxidation of lipoproteins.

The oxidative modification of lipoproteins has been implicated in atherogenesis, suggesting a protective role of circulating antioxidants. Vitamin C (ascorbic acid, 1 g/day) and vitamin E (dl alpha-tocopheryl acetate, 800 IU/day) were administered to healthy female and male volunteers. Lipoproteins with density < 1.063 g/mL were isolated from serum before and after vitamin supplementation and incubated with copper (Cu) or mononuclear cells (MC) plus Cu. Administration of vitamins C and E together to 4 subjects for 10 days resulted in a 57% (range 40-72%) decrease in Cu-catalyzed production of thiobarbituric acid reactive substances (TBARS) under the following conditions of assay: incubation times of 0-8 hours, Cu concentrations of 0-10 microM lipoprotein protein concentrations of 0.1–0.5 mg/mL. Decreases in other parameters of lipoprotein oxidation, i.e,, electrophoretic mobility, production of conjugated dienes and modification of amino groups, were also observed. Vitamin E administration alone produced a 52% inhibition and vitamin C alone a 15% inhibition of TBARS formation. Vitamins C and E supplementation resulted in a 78% decrease in the susceptibility of lipoproteins to MC-mediated oxidation. There was a strong inverse correlation (r = -0.64, p < 0.0007) between vitamin E levels in the lipoproteins and TBARS production in samples from 12 subjects administered vitamins C and E. In 3 individuals vitamin E levels remained low and in 2 of these subjects there was no effect of vitamins C and E administration on TBARS production. These results suggest a protective role of antioxidant vitamins and significant individual variability in response.     

Avenanthramides and phenolic acids from oats are bioavailable and act synergistically with vitamin C to enhance hamster and human LDL resistance to oxidation

The intake of phenolic acids and related polyphenolic compounds has been inversely associated with the risk of heart disease, but limited information is available about their bioavailability or mechanisms of action. Polyphenolics, principally avenanthramides, and simple phenolic acids in oat bran phenol-rich powder were dissolved in HCl:H(2)O:methanol (1:19:80) and characterized by HPLC with electrochemical detection. The bioavailability of these oat phenolics was examined in BioF1B hamsters. Hamsters were gavaged with saline containing 0.25 g oat bran phenol-rich powder (40 micromol phenolics), and blood was collected between 20 and 120 min. Peak plasma concentrations of avenanthramides A and B, p-coumaric, p-hydroxybenzoic, vanillic, ferulic, sinapic, and syringic acids appeared at 40 min. Although absorbed oat phenolics did not enhance ex vivo resistance of LDL to Cu(2+)-induced oxidation, in vitro addition of ascorbic acid synergistically extended the lag time of the 60-min sample from 137 to 216 min (P < or = 0.05), unmasking the bioactivity of the oat phenolics from the oral dose. The antioxidant capability of oat phenolics to protect human LDL against oxidation induced by 10 micromol/L Cu(2+) was also determined in vitro. Oat phenolics from 0.52 to 1.95 micromol/L increased the lag time to LDL oxidation in a dose-dependent manner (P < or = 0.0001). Combining the oat phenolics with 5 micromol/L ascorbic acid extended the lag time in a synergistic fashion (P < or = 0.005). Thus, oat phenolics, including avenanthramides, are bioavailable in hamsters and interact synergistically with vitamin C to protect LDL during oxidation.     

Differentiating copper and arsenic toxicity using biochemical biomarkers in Asellus aquaticus and Dreissena polymorpha

Biomarkers of metal exposure are well known, but how a suite of such biomarkers will respond if the metal is also an oxidizing agent or causes oxidative stress is unclear. This study compares the effects of copper and arsenic, two metals with different oxidizing potential, on freshwater invertebrates. Dreissena polymorpha and Asellus aquaticus were exposed to nominal concentrations of copper (100 microg/L) or arsenic (80 microg/L) over 7 days, and physiological stress was examined by measuring metallothionein (MT) induction, thiobarbituric acid reactive substances (TBARS), and Na(+)/K(+)-ATPase activity. Both species showed increased levels of MT during 7-day Cu exposure tests and transient changes in lipid peroxidation (TBARS) which decreased to control levels by day 7. Arsenic had no effect on TBARS and only a transitory effect on MT in D. polymorpha over 7 days, although it initially induced lipid peroxidation in A. aquaticus on day 3. No inhibition of the Na(+)/K(+)-ATPase enzyme was observed for exposed organisms, and baseline values reported here, for A. aquaticus, 1.1 micromol Pi/mg/h, and for D. polymorpha, 0.38 micromol Pi/mg/h, are probably the first reported for these species.     

Theaflavins in black tea and catechins in green tea are equally effective antioxidants

Green tea catechins, including (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), are oxidized and dimerized during the manufacture of black tea and oolong tea to form orange-red pigments, theaflavins (TF), a mixture of theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B) and theaflavin-3,3'-digallate (TF3). The present study was designed to compare the antioxidant activities of individual TF with that of each catechin using human LDL oxidation as a model. All catechins and TF tested inhibited Cu(+2)-mediated LDL oxidation. Analysis of the thiobarbituric acid-reactive substances (TBARS) and conjugated dienes produced during LDL oxidation revealed that the antioxidant activity was in the order: TF3 > ECG > EGCG > or = TF2B > or = TF2A > TF1 > or = EC > EGC. Four TF derivatives also demonstrated a dose-dependent antioxidant activity in Cu(+2)-mediated LDL oxidation at concentrations of 5-40 micromol/L. These results demonstrate that the TF present in black tea possess at least the same antioxidant potency as catechins present in green tea, and that the conversion of catechins to TF during fermentation in making black tea does not alter significantly their free radical-scavenging activity.