Protection of lung fibroblast MRC-5 cells against hydrogen peroxide-induced oxidative damage by 0.1-2.8 kDa antioxidative peptides isolated from whey protein hydrolysate

Antioxidative peptides (0.1-2.8 kDa) obtained from gel filtration of Alcalase-hydrolysed whey protein were subjected to individual peptide isolation by RP-HPLC. The sub-fraction P4 and a prominent pentapeptide identified by mass spectrometry (Val-His-Leu-Lys-Pro) (P4c) were found to be highly antioxidative, therefore, used to assess the efficacy against hydrogen peroxide (H(2)O(2))-induced human lung fibroblast MRC-5 cell oxidative injury. MRC-5 cells were damaged by incubation with H(2)O(2), but cell death was significantly reduced when exposed to P4 and P4c (P<0.05). Compared to the H(2)O(2)-damaged model control, P4 and P4c enhanced the activity of cell superoxide dismutase, glutathione peroxidase, and catalase, and decreased the levels of malonaldehyde (P<0.05). These results, with a more pronounced action of P4c than P4, demonstrated that antioxidative peptides had a significant protection of MRC-5 cells against the toxicity caused by H(2)O(2).     

牡丹花蕊黄酮对H2O2诱导RAW264.7巨噬细胞损伤的保护作用

目的：研究牡丹花蕊黄酮对H2O2诱导损伤的RAW264.7巨噬细胞的保护作用。方法：实验分为空白组、H2O2损伤组、VC对照组和牡丹花蕊黄酮低、中、高剂量组。应用H2O2建立RAW264.7巨噬细胞氧化损伤模型,噻唑蓝法测定细胞存活率,试剂盒法测定细胞和细胞培养液中谷胱甘肽和丙二醛含量及过氧化氢酶、超氧化物歧化酶、乳酸脱氢酶活力。结果：牡丹花蕊黄酮的质量浓度在10～30 μg/mL范围内时,可显著促进RAW264.7巨噬细胞的增殖（P＜0.05）。与H2O2损伤组相比,牡丹花蕊黄酮各剂量组能够提高细胞及细胞培养液中总抗氧化能力,谷胱甘肽过氧化物酶、超氧化物酶、过氧化氢酶活力以及还原型谷胱甘肽含量,降低细胞及细胞培养液中丙二醛含量,提高细胞内乳酸脱氢酶的水平。结论：牡丹花蕊黄酮可以促进RAW264.7巨噬细胞的增殖,提高H2O2损伤的RAW264.7巨噬细胞的抗氧化能力,且存在剂量依赖效应。     

绿豆皮黄酮对H2O2诱导人脐静脉血管内皮细胞损伤的保护作用

目的:研究绿豆皮黄酮对H2O2诱导损伤人脐静脉血管内皮细胞的保护作用及其机制。方法:用体积分数70%的乙醇提取绿豆皮中黄酮,采用高效液相色谱法测定其有效成分;通过H2O2诱导HUVEC细胞损伤,建立细胞氧化损伤模型。试验被分为正常对照组、H2O2组、维生素C组、绿豆皮黄酮低、中、高剂量组(20,60,80μg/m L),通过MTT法测定细胞增殖能力,生化比色法检测各组细胞及培养液中的超氧化物酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、乳酸脱氢酶(LDH)活性以及谷胱甘肽(GSH)和丙二醛(MDA)含量。结果:H2O2呈剂量依赖性降低内皮细胞活力,并引起细胞凋亡。其中1 000μmol/L H2O2处理HUVEC后,与正常组相比,细胞存活率明显受到抑制,而绿豆皮各剂量组能显著提高细胞和细胞培养液中的GSH-Px、SOD、GSH活性,降低MDA含量,同时降低细胞中LDH活性并增强细胞培养液中的LDH含量。结论:绿豆皮黄酮能抑制H2O2诱导的内皮细胞凋亡,减轻H2O2对内皮细胞的损伤作用,其机制是:绿豆皮黄酮抑制损伤细胞脂质过氧化,提高机体抗氧化酶活性,清除自由基。     

Antioxidative activities of soymilk fermented with lactic acid bacteria and bifidobacteria

To further the goal of developing a probiotic dietary adjunct using soymilk, soymilk is fermented with lactic acid bacteria (Lactobacillus acidophilus CCRC 14079 or Streptococcus thermophilus CCRC 14085) and bifidobacteria (Bifidobacterium infantis CCRC 14633 or Bifidobacterium longum B6) individually, and in conjunction. We investigate several antioxidative activities including the inhibition of ascorbate autoxidation, the scavenging effect of superoxide anion radicals and hydrogen peroxide, and the reducing activity exerted by different varieties of fermented soymilks. In addition, the effect of spray-drying and freeze-drying on changes in antioxidative activity is examined. We find that in fermented soymilk both the inhibition of ascorbate autoxidation, and the reducing activity and scavenging effect of superoxide anion radicals varied with the starters used, but nevertheless are significantly higher than those found in unfermented soymilk. In general, antioxidative activity in soymilk fermented with lactic acid bacteria and bifidobacteria simultaneously is significantly higher (P < 0.05) than that fermented with either individually. Moreover, antioxidative activity increases as the fermentation period is extended. However, unfermented soymilk shows an H2O2-scavenging effect, while there is no scavenging effect except for the accumulation of H2O2 in fermented soymilk. Finally, we find that freeze-drying causes a significantly lesser (P < 0.05) reduction in the antioxidative activity of soymilk than does spray-drying. Irrespective of the drying method and the starters used for fermentation. The antioxidative activity of fermented soymilk reduces after drying yet remains higher than that of dried unfermented soymilk.     

Antioxidative and Anti-Inflammatory Neuroprotective Effects of Astaxanthin and Canthaxanthin in Nerve Growth Factor Differentiated PC12 Cells

ABSTRACT: Nerve growth factor differentiated PC12 cells were used to examine the antioxidative and anti‐inflammatory effects of astaxanthin (AX) and canthaxanthin (CX). PC12 cells were pretreated with AX or CX at 10 or 20 μM, and followed by exposure of hydrogen peroxide (H₂O₂) or 1‐methyl‐4‐phenylpyridinium ion (MPP⁺) to induce cell injury. H₂O₂ or MPP⁺ treatment significantly decreased cell viability, increased lactate dehydrogenase (LDH) release, enhanced DNA fragmentation, and lowered mitochondrial membrane potential (MMP) (P < 0.05). The pretreatments from AX or CX concentration‐dependently alleviated H₂O₂ or MPP⁺‐induced cell death, LDH release, DNA fragmentation, and MMP reduction (P < 0.05). Either H₂O₂ or MPP⁺ treatment significantly increased malonyldialdehyde (MDA) and reactive oxygen species (ROS) formations, decreased glutathione content, and lowered glutathione peroxidase (GPX) and catalase activities (P < 0.05). The pretreatments from AX or CX significantly retained GPX and catalase activities, and decreased MDA and ROS formations (P < 0.05). H₂O₂ or MPP⁺ treatment significantly decreased Na⁺‐K⁺‐ATPase activity, elevated caspase‐3 activity and levels of interleukin (IL)‐1, IL‐6, and tumor necrosis factor (TNF)‐α (P < 0.05); and the pretreatments from these agents significantly restored Na⁺‐K⁺‐ATPase activity, suppressed caspase‐3 activity and release of IL‐1, IL‐6, and TNF‐α (P < 0.05). Based on the observed antioxidative and anti‐inflammatory protection from AX and CX, these 2 compounds were potent agents against neurodegenerative disorder.     

Effects of Fermentation and Storage on the Concentration of Orotic Acid and Uric Acid in Skim Milk

Skim milk (SM) and skim milk yogurt (SMY) were produced and analyzed using high performance liquid chromatography (HPLC) for the presence of two organic acids–orotic acid (OA) and uric acid (UA). The concentration of OA in SM and SMY at 0 days was 106.2 and 46.1 ppm, respectively. After fermentation OA concentration was 56% lower (P <0.05) in SMY than in nonfermented SM. UA content of SM and SMY at 0 days was 23.3 and 20.1 ppm, respectively. Unlike OA, the UA contents were not significantly altered after fermentation. No significant differences were detected in the concentrations of OA and UA when values of SM and SMY of 0 days were compared with those after 3 days storage.     

虎杖苷对四氧嘧啶诱导的大鼠胰岛细胞损伤的保护作用

目的:研究虎杖苷(Polydatin)对四氧嘧啶(Alloxan)诱导的大鼠胰岛素瘤INS-1细胞损伤的保护作用。方法:利用细胞增殖实验分别检测四氧嘧啶或虎杖苷对INS-1细胞增殖的影响,确定给药浓度;实验分为空白组、模型组(18 mmol/L四氧嘧啶)和不同浓度虎杖苷保护组(分别给予25、50 μg/mL虎杖苷,同时给予18 mmol/L四氧嘧啶),检测细胞存活率、LDH释放、胰岛素分泌、凋亡相关Caspase-3和Caspase-9的活性、活性氧簇ROS、一氧化氮NO、丙二醛MDA的含量及抗氧化相关超氧化物歧化酶SOD、还原型谷胱甘肽GSH水平。结果:10~30 mmol/L四氧嘧啶处理使INS-1细胞存活率显著降低(P<0.05),18 mmol/L四氧嘧啶处理细胞贴壁数目减少,LDH释放升高,胰岛素分泌量降低,凋亡相关Caspase-3和Caspase-9的活性显著升高(P<0.05),氧化应激相关ROS、NO和MDA含量显著提高(P<0.05),抗氧化相关SOD和GSH水平显著降低(P<0.05)。5~100 μg/mL虎杖苷对INS-1细胞无毒性作用,相较于模型组,25和50 μg/mL虎杖苷能显著提高四氧嘧啶诱导INS-1细胞存活率,改善细胞形态,降低LDH活性,增加胰岛素分泌量,抑制凋亡相关Caspase-3和Caspase-9酶活性,抑制四氧嘧啶诱导的氧化损伤,提高抗氧化相关酶活力(P<0.05)。结论:虎杖苷对四氧嘧啶诱导的INS-1细胞损伤有显著保护作用,其作用机制可能与抑制氧化应激及凋亡有关。     

乳源β-酪啡肽-5对C2C12细胞的抗氧化损伤作用

通过建立过氧化氢(H2O2)对C2C12细胞的氧化损伤模型,从细胞水平探讨β-酪啡肽-5(β-casomorphin5,β-CM5)对H2O2致氧化应激损伤的保护作用及其可能机制。方法：1) MTT法测定72h内β-CM5对C2C12细胞活力的影响,筛选安全剂量;2)测定不同浓度H2O2对C2C12细胞活力的影响,筛选H2O2的最佳剂量和作用时间;3)测定β-CM5对H2O2损伤后细胞活力的影响;4)检测培养液中超氧化物歧化酶(superoxidedismutase,SOD)、乳酸脱氢酶(lactate dehydrogenase,LDH)的活性。结果：1)β-CM5各浓度组MTT值与对照组无差异;2)0.25mmol/L的H2O2作用于C2C12细胞 1h,MTT值显著低于对照组 (P＜0.01);3)与损伤组相比,β-CM5预保护组的MTT值显著升高(P＜0.05),治疗组MTT值无明显变化;4)与损伤组相比,β-CM5预保护组的SOD活性显著提高(P＜0.05),LDH活性显著下降(P＜0.05)。结论：β-CM5具有较强的抗氧化作用,对H2O2损伤的C2C12细胞有明显的保护作用,其机制可能与增强抗氧化酶活力和维持细胞完整性有关。     

S‐Allyl cysteine,S‐ethyl cysteine and S‐propyl cysteine alleviate oxidative stress‐induced damage within PC12 cells

BACKGROUND: The PC12 cell line is a suitable model for the investigation of neurodegenerative diseases. In this study, PC12 cells were used to examine in vitro antioxidative and antiapoptotic protection by S‐allyl cysteine (SAC), S‐ethyl cysteine (SEC) and S‐propyl cysteine (SPC). PC12 cells were treated with these agents at 5 and 10 µmol L^?1 before exposure to hydrogen peroxide (H₂O₂). RESULTS: H₂O₂ treatment significantly decreased mitochondrial membrane potential (MMP) and cell viability and increased lactate dehydrogenase (LDH) release and DNA fragmentation (P < 0.05). The pre‐treatments with SAC, SEC and SPC significantly and concentration‐dependently elevated cell viability and MMP and lowered LDH release and DNA fragmentation (P < 0.05). H₂O₂ treatment also significantly increased levels of malondialdehyde (MDA), reactive oxygen species (ROS) and oxidised glutathione (GSSG) and decreased glutathione (GSH) content (P < 0.05). The pre‐treatments with SAC, SEC and SPC significantly decreased subsequent H₂O₂‐induced formation of MDA, ROS and GSSG (P < 0.05) and also alleviated H₂O₂‐induced GSH depletion (P < 0.05). Finally, H₂O₂ treatment significantly decreased Na⁺‐K⁺‐ATPase activity and elevated caspase‐3 activity (P < 0.05). The pre‐treatments with SAC, SEC and SPC significantly attenuated H₂O₂‐induced Na⁺‐K⁺‐ATPase activity reduction and caspase‐3 activity elevation (P < 0.05). CONCLUSION: The results obtained support that the three cysteine‐containing compounds studied are potent neuroprotective agents. Copyright © 2008 Society of Chemical Industry     

姜黄素对H2O2诱导血小板凋亡的抑制作用及分子机制

目的：血小板凋亡在心血管疾病发生发展过程中发挥重要作用，姜黄素（curcumin，Cur）是存在于姜科植物根茎中的一种多酚类化合物，具有多种生物学活性，但是Cur对血小板凋亡是否具有调控作用尚鲜见报道，本研究通过体外实验探讨Cur对H2O2诱导血小板凋亡的影响及其潜在的机制。方法：用不同浓度（0、1、10、100 μmol/L）的Cur与健康人纯化血小板在体外共同孵育30 min，然后加入H2O2（100 μmol/L）干预血小板60 min，用流式细胞术检测血小板磷脂酰丝氨酸的暴露水平和线粒体膜电位（ΔΨm）去极化水平；用酶联免疫吸附法测定血小板凋亡蛋白Caspase-3和Caspase-9活化水平、胞内总活性氧以及超氧化物生成水平；用Western blot蛋白免疫印迹法检测血小板促凋亡蛋白Bax、Bak和细胞色素c的表达水平。结果：与对照组相比，10、100 μmol/L Cur显著抑制H2O2诱导的血小板磷脂酰丝氨酸暴露和ΔΨm去极化（P＜0.05）；同时，Western blot结果显示，Cur能显著降低H2O2诱导的血小板促凋亡蛋白Bax、Bak和细胞色素c的表达水平的升高（P＜0.05）；酶联免疫吸附测定结果表明，H2O2诱导的血小板Caspase-3和Caspase-9的活化可被10、100 μmol/L Cur显著抑制（P＜0.05）；此外，H2O2处理时，血小板内总活性氧水平和超氧化物水平显著上调，Cur干预可显著抑制胞内总活性氧和超氧化物生成（P＜0.05）。结论：Cur具有显著抑制H2O2诱导的血小板凋亡的作用。     

小檗碱活化AMPK-eNOS减轻油酸所致人主动脉内皮细胞损伤

目的：考察小檗碱对油酸所致内皮细胞损伤的保护作用,并探究其作用机制。方法：以体外培养人主动 脉内皮细胞系（human aorta endothelial cells,HAEC）为受试对象;分别以油酸、油酸联合小檗碱、油酸联合单 磷酸腺苷活化蛋白激酶（adenosine monophosphate-activated protein kinase,AMPK）激活剂（AICAR）或抑制剂 （Compound C）处理HAEC;采用油红O染色法观察细胞内脂滴合成;采用比色法检测细胞内甘油三酯、总胆 固醇含量,硝酸还原酶法检测NO的水平,2’,7’-二氯荧光黄双乙酸盐探针检测细胞内总活性氧（reactive oxygen species,ROS）水平,Western Blotting检测细胞总AMPK、内皮型一氧化氮合酶（endothelial nitric oxide synthase, eNOS）及其磷酸化（p-AMPK、p-eNOS）水平。结果：油酸可浓度依赖性地抑制细胞增殖,小檗碱组各项指标 较正常对照组无显著性差异,油酸联合小檗碱组的细胞活性较油酸组明显好转（P＜0.01）。与正常对照组比较, 油酸组的脂质浸润程度明显,油酸在不同浓度下使内皮细胞的脂质含量呈剂量依赖性增加,加入小檗碱可明显减 少这种脂质堆积。油酸组的NO水平较正常对照组明显减少,小檗碱能显著抑制油酸所致的内皮NO水平的减少, 并且减少由于油酸所致的ROS水平的升高;油酸抑制了AMPK的活化,使p-AMPK和p-eNOS的蛋白水平明显降低 （P＜0.01）;小檗碱可明显逆转油酸所致AMPK和eNOS磷酸化水平下降,Compound C可拮抗其作用。结论：小檗 碱可减轻油酸所致血管内皮细胞损伤,或与其活化AMPK/eNOS信号相关。     

矢车菊素-3-O-葡萄糖苷保护RAW264.7细胞免受过氧化氢诱导的氧化损伤

本研究旨在探究矢车菊素-3-O-葡萄糖苷（cyanidin-3-O-glucoside,C3G）对H2O2诱导RAW264.7细胞氧化损伤的保护作用及其机制。通过噻唑蓝法测定C3G和过氧化氢分别对RAW264.7细胞存活率的影响;采用酶联免疫吸附测定法检测细胞内超氧化物歧化酶（superoxide dismutase,SOD）和谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）活力以及一氧化氮（nitric oxide,NO）和丙二醛（malondialdehyde,MDA）水平;利用2’,7’-二氯荧光素二乙酸酯活性氧荧光探针检测细胞内活性氧（reactive oxygen species,ROS）水平;通过逆转录定量聚合酶链式反应和Western blot法分别测定相关mRNA和蛋白表达水平。结果表明,C3G（6.25～25.00 μmol/L）能显著抑制H2O2诱导RAW264.7细胞活性降低（P＜0.05）。C3G显著降低H2O2诱导RAW264.7细胞内ROS过表达、MDA水平和NO释放（P＜0.05）,显著增加SOD和GSH-Px活力（P＜0.05）。此外,与空白对照相比,400 μmol/L H2O2处理组中,蛋白激酶Mst1/2和Kelch样环氧氯丙烷相关蛋白Keap1的mRNA及蛋白相对表达水平显著上调（P＜0.05）,而细胞中核因子E2相关因子和下游抗氧化酶HO-1的mRNA及蛋白相对表达水平显著下调（P＜0.05）;而采用C3G干预RAW264.7细胞,上述相关mRNA及蛋白的相对表达水平被逆转。结论：C3G对H2O2诱导RAW264.7细胞氧化损伤保护作用,可能与激活Mst/Nrf2信号通路和提高抗氧化酶活性有关。     

熊果酸对H22荷瘤小鼠抗肿瘤及肠道细菌群落结构多样性的影响

研究熊果酸对H22荷瘤小鼠抗肿瘤及肠道细菌的影响。皮下接种H22肝癌细胞构建移植瘤小鼠模型,设正常组、模型组、阳性对照组（环磷酰胺）和熊果酸组（低、中、高剂量）,连续给药3周后,计算抑瘤率和肝脾指数,检测血清T淋巴细胞亚群、白细胞介素-2（IL-2）和肿瘤坏死因子α（TNF-α）浓度,采用高通量测序技术分析熊果酸对H22荷瘤肠道细菌群落结构多样性的影响。结果显示,与模型组相比,熊果酸各剂量组均能显著减少移植瘤质量（P<0.05）,其中熊果酸中、高剂量组能显著提高荷瘤小鼠血清中T细胞亚群、IL-2和TNF-α的含量（P<0.05）。主成分分析（Principal Component Analysis,PCA）显示,与正常组比较,模型组和熊果酸低剂量组小鼠肠道细菌相似性差异显著（P<0.05）,而熊果酸中剂量组和高剂量组小鼠肠道细菌相似性差异不显著（P>0.05）。熊果酸各剂量组肠道细菌在门水平和科水平的比例和分布均比模型组更接近正常组。与模型组比较,熊果酸小鼠肠道Akkermansia和Lactobacillus丰度显著增加（P<0.05）,而Muribaculum显著减少（P<0.05）。表明熊果酸可抑制肿瘤生长,增强H22荷瘤小鼠免疫力,对肿瘤小鼠肠道细菌菌群紊乱具有一定恢复作用。     

蛋清源活性肽对过氧化氢诱导的HEK293细胞抗氧化酶活力及白细胞介素8分泌的影响

食源性抗氧化肽由于抗氧化能力较好、安全性高,逐渐成为多肽研究领域的热点。本实验以H2O2诱导HEK293细胞损伤建立氧化损伤模型,研究了蛋清源活性肽WNWAD（Trp-Asn-Trp-Ala-Asp）及其结构改造肽WNW（Trp-Asn-Trp）、WAD（Trp-Ala-Asp）、WN（Trp-Asn）对H2O2诱导损伤的HEK293细胞的存活率、活性氧（reactive oxygen species,ROS）水平、抗氧化酶活力及细胞因子白介素8（interleukin-8,IL-8）分泌的影响。结果表明：蛋清源活性肽对HEK293细胞存活率的影响极显著（P＜0.01）,不同浓度蛋清源活性肽WNWAD、WNW、WAD、WN作用于氧化损伤的HEK293细胞后,其存活率明显提高,呈现浓度依赖性;其中1.0 μmol/L蛋清源活性肽WNWAD、WNW、WAD、WN处理细胞后,存活率从损伤组的（48.0±2.4）%分别提高到（99.7±1.8）%、（69.4±3.2）%、（78.9±5.1）%、（72.1±3.6）%,与损伤组有极显著性差异（P＜0.01）;H2O2诱导HEK293细胞内ROS的产生,经过活性肽预处理后细胞内ROS的水平极显著降低（P＜0.01）;随着蛋清源活性肽WNWAD、WNW、WAD、WN浓度的升高,总超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶3 种酶的活力均有所提高,呈现浓度依赖型关系。最后利用酶联免疫吸附测定试剂盒测定了HEK293细胞中IL-8的分泌量,经过H2O2处理的HEK293细胞上清液中IL-8含量极显著升高（P＜0.01）,加入WNWAD、WNW、WN、WAD后,细胞中的IL-8含量均有所降低,其中WNWAD和WN影响显著（P＜0.05）。以上结果显示蛋清源活性肽对降低HEK293细胞氧化应激水平和提高细胞抗氧化能力有积极的影响。     

不同形态硒与VE联用对H_2O_2诱导人脐静脉血管内皮细胞氧化应激损伤的保护作用

目的:研究不同形态硒化合物(有机硒:L-硒甲基硒代半胱氨酸;无机硒:亚硒酸钠)单独使用及其与VE联合使用后对H_2O_2诱导人脐静脉血管内皮细胞(human umbilical vein endothelial cells,HUVECs)产生氧化应激损伤的保护作用。方法:采用体外细胞培养方法,将HUVECs随机分为7组:对照组、H_2O_2组、L-硒甲基硒代半胱氨酸(L-Se-methylselenocysteine,L-Se MSC)组、亚硒酸钠(sodium selenite,SS)组、VE组、L-Se MSC+VE联用组、SS+VE联用组。经不同样品干预处理后,采用四甲基偶氮唑蓝(methyl thiazolyl tetrazolium,MTT)法检测HUVECs存活率;检测各组细胞内脂质氧化终产物丙二醛(malondialdehyde,MDA)含量以及超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活性的变化。结果:各处理组HUVECs存活率之间没有显著差异;与H_2O_2组比较,0.1 mg/L亚硒酸钠、10 mg/L VE处理能使HUVECs内MDA生成量显著减少,SOD和GSH-Px活性显著升高,并且亚硒酸钠和VE联合使用在细胞水平上具有显著的协同作用,而L-Se MSC组与对照组无显著差异。结论:亚硒酸钠和VE均可保护由H_2O_2诱导引起的HUVECs氧化损伤,提高HUVECs抗氧化能力,并且亚硒酸钠和VE联用具有明显的协同抗氧化作用。     

大黄酸对正常和氧化损伤内皮细胞的增殖和氧化保护作用

目的：观察大黄酸对正常和氧化损伤的人脐静脉血管内皮细胞(HUVEC)的影响。方法：建立H2O2氧化损伤模型,采用不同浓度的大黄酸对内皮细胞进行处理,检测内皮细胞乳酸脱氢酶(LDH)释放率、丙二醛(MDA)含量、一氧化氮(NO)含量、一氧化氮合酶(NOS)活力和超氧化物歧化酶(SOD) 活力及谷胱甘肽过氧化物酶(GSH-Px) 活力的变化;采用流式细胞术研究内皮细胞的凋亡情况,探讨大黄酸对内皮细胞的保护作用。结果：大黄酸浓度在16μmol/L以下时,对HUVEC的增殖无显著性影响;浓度在2μmol/L以上时,减轻HUVEC受到氧化损伤的程度,对氧化性损伤具有保护作用;同时降低了LDH释放率,下调了MDA含量,提高了NO含量和NOS、SOD、GSH-Px的酶活力,显著减少了细胞凋亡率。结论：HUVEC经2～16μmol/L大黄酸处理,可以有效减轻H2O2对其造成的氧化损伤,维持正常的生理形态。     

CodY在单核细胞增生李斯特菌抗氧化胁迫中的作用

目的：探究全局性转录调控因子CodY在单核细胞增生李斯特菌（Listeria monocytogenes，Lm）抗氧化应激中的作用。方法：利用H2O2对处于对数中期（OD600 nm=0.65）的Lm野生株EGDe和CodY缺失株EGDeDcodY进行氧化胁迫，比较两菌株氧化耐受能力、抗氧化应激物（过氧化氢酶（catalase，CAT）、超氧化物歧化酶（superoxide dismutase，SOD）和谷胱甘肽（glutathione，GSH））活性或含量差异；通过随机扩增多态性DNA技术比较两菌株基因组模板稳定性（genomic template stability，GTS）；利用实时聚合酶链式反应（real-time polymerase chain reaction，real-time PCR）检测两菌株抗氧化应激物编码基因以及DNA损伤诱导反应（SOS反应）重要基因的转录表达变化。结果：1）H2O2对EGDe的最低抑菌浓度和最低杀菌浓度大约是EGDeDcodY的2 倍，当H2O2浓度超过20 mmol/L时，EGDeDcodY抑菌圈直径极显著大于EGDe（P≤0.01）。2）200 mmol/L H2O2完全抑制EGDeDcodY生长而EGDe生长速率则有所减慢。3）H2O2胁迫使EGDe和EGDeDcodY中CAT活力均下降，但转录水平并没有显著变化；SOD活力在两菌株内无明显变化，但转录表达在EGDe和EGDeDcodY中差异高度显著（P≤0.001）；值得注意的是，GSH编码基因的转录表达和其含量在EGDe和EGDeDcodY中变化趋势基本一致，随H2O2胁迫时间延长呈先显著下降后略微上升，而且与EGDe相比，GSH在EGDeDcodY中的转录表达水平具有极显著差异（P≤0.01）。4）EGDe和EGDeDcodY的GTS分别为93.1%和80.0%；real-time PCR显示EGDeDcodY中参与SOS反应的重要基因（recA、lexA、recR、lmo1302、lmo1975）转录表达受到高度显著抑制（P≤0.001），而EGDe中recA、lmo1302和lmo1975的转录表达被激活。结论：CodY缺失导致细菌在H2O2胁迫下的耐受能力和生长速率显著降低，GSH含量下降，GTS降低，参与SOS反应的重要基因表达受到显著抑制，表明CodY在Lm抵御氧化胁迫中发挥了重要的调控作用。     

Effects of water-soluble natural antioxidants on photosensitized oxidation of conjugated linoleic acid in an oil-in-water emulsion system

ABSTRACT:  The effect of photosensitized oxidation of conjugated linoleic acid in an oil-in-water (o/w) emulsion system was studied. Water-soluble natural antioxidants, including apple polyphenols from apple extract, green tea extract, 4-hydroxy-2(or 5)-ethyl-5(or2)-methyl-3(2H)-furanone(HEMF), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), and ascorbic acid, were tested for antioxidant activity in this system. The green tea extract showed the highest antioxidant activity followed by ascorbic acid. Apple polyphenols did not give significant antioxidant activity. HEMF and HDMF exhibited a prooxidant effect. The antioxidant activity of tea catechins was also investigated. Of them, EGCG and ECG exhibited antioxidant activity at 50 ppm, but the antioxidant activity between them was not significantly different ( P < 0.05). Comparatively, EC, EGC, and GCG showed no significant antioxidative effect at 50 ppm. When the concentration increased to 100 ppm, the antioxidant activity of ECG and EGCG significantly increased compared with that at 50 ppm, and EGCG had higher antioxidant activity than ECG. GCG also showed significant antioxidant activity at 100 ppm. EGCG exhibited the highest antioxidant activity among the tea catechins in the emulsion system at 100 ppm.     

圣草次苷的合成及其对过氧化氢诱导人脐静脉内皮细胞氧化损伤的保护作用

以橙皮苷为原料,经三氯化铝-吡啶去甲基反应合成药用天然产物圣草次苷,产物通过1H核磁共振（nuclear magnetic resonance,NMR）和13C NMR进行结构确证,并探究其对过氧化氢（H2O2）诱导氧化应激损伤的人脐静脉内皮细胞系（human umbilical vein endothelial cells,HUVEC）细胞的保护作用机制。结果表明：圣草次苷对HUVEC细胞无毒性作用,能显著提高氧化损伤HUVEC细胞的存活率（P＜0.05）,但无显著剂量效应;显著降低细胞中活性氧水平和丙二醛含量（P＜0.05）,显著提高超氧化物歧化酶、谷胱甘肽过氧化物酶、过氧化氢酶等抗氧化酶的活力（P＜0.05）;显著上调Bcl-2/Bax蛋白比值和下调p53蛋白表达（P＜0.05）。结论：圣草次苷能有效阻止H2O2所致HUVEC细胞损伤,该作用与圣草次苷的抗氧化活性和抑制细胞死亡有关。