葡萄籽粗多糖的体内外抗氧化作用

为了研究葡萄籽粗多糖(crude polysaccharides from grape seeds,GSCPs)体外抗氧化作用及对秀丽隐杆线虫的体内抗氧化作用,采用水提醇沉法提取GSCPs,检测GSCPs对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基和羟自由基的清除作用及对DNA氧化损伤的抑制作用;建立RAW 264.7巨噬细胞氧化损伤模型,在细胞水平探讨GSCPs的抗氧化能力;同时利用秀丽隐杆线虫研究GSCPs的体内抗氧化功能。体外实验结果表明:GSCPs可有效清除自由基,抑制DNA的氧化损伤,质量浓度为0.4mg/mL的GSCPs对DPPH自由基的清除率达84%,对羟自由基清除率为89%;GSCPs可以下调H₂O₂诱导的RAW 264.7巨噬细胞活性氧(reactive oxygen species,ROS)水平,正向调节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)活性,质量浓度为0.2mg/mL的GSCPs处理组可使细胞内SOD活性从H₂O₂处理组的81.1%升至96.3%,GSH-Px活性从H₂O₂处理组的92.1%升至99.6%。此外,GSCPs可延长秀丽隐杆线虫寿命,提高其对抗急性氧化应激的能力,有效清除秀丽隐杆线虫体内的ROS。质量浓度为0.8mg/mL GSCPs处理组秀丽隐杆线虫的平均寿命较对照组延长27.67%,将急性氧化应激的秀丽隐杆线虫平均存活时间延长33.58%,秀丽隐杆线虫体内ROS生成量较对照组可降低56.33%。因此,葡萄籽粗多糖在体内外均表现出良好的抗氧化性,可用于抗氧化功能产品的开发。     

仿刺参精酶解工艺的优化及酶解液的抗氧化活性

作为性腺的仿刺参精富含蛋白质、多糖和多种活性物质,被单独收集并酶解,用于开发新型的海洋活性多肽。选用木瓜蛋白酶水解仿刺参精,以水解度(DH)为评价标准,通过单因素实验和响应面法确定最佳水解条件。当木瓜蛋白酶与底物质量比为4.4%时,在70 ℃条件下反应4 h,水解度最高可达到43.18%。随后,采用Pall Minimate超滤系统从酶解液中分离梯度肽,得到分子质量范围分别为<1 ku、1~5 ku和5~10 ku的多肽,测定它们对超氧自由基(·O₂-)和羟基自由基(·OH)的清除效率。抗氧化试验结果显示,分子质量<1 ku的多肽对·O₂-的清除能力最强,表明该肽段具有较好的抗氧化活性。仿刺参精的水解产物作为一种具有抗氧化活性的海洋多肽,有望用于保健品、医药和化妆品行业。     

铁皮石斛多糖多肽的发酵法提取及其抗氧化活性分析

目的 研究一种有效的铁皮石斛多糖多肽提取方法,并分析其基本性质及体外抗氧化活性。方法 以铁皮石斛为研究对象,采用芽孢杆菌发酵法对铁皮石斛进行提取,用蒽酮-硫酸法和双缩脲法分别测定铁皮石斛提取液的多糖和多肽含量,以传统热水浸提法和超声波辅助提取法为对照,通过提取液对自由基清除能力、螯合金属离子能力、抑制亚油酸自氧化能力、抑制红细胞溶血能力、保湿能力等指标,评价芽孢杆菌发酵提取液的抗氧化活性。结果 芽孢杆菌发酵提取法工艺参数为投料比例1:25(g/mL),发酵pH6,发酵温度33.5 ℃,发酵时间46 h,此时多糖提取率为37.21%,多肽含量高达4.43 mg/ kg,分子量主要分布在2000 Da以下,占84.95 %。提取液对羟基自由基(.OH)、DPPH自由基(DPPH.)和 ABTS自由基(ABTS₊^.)有较强的清除能力,Fe₂₊^螯合能力67%、亚油酸抑制率53%、H₂O₂诱导溶血抑制率64.34%、皮肤含水量提高33.57 %。结论 芽孢杆菌发酵法提取铁皮石斛,提取液多糖多肽含量高,具有较好抗氧化性和保湿性,为铁皮石斛在食品和化妆品领域的开发利用提供了一定的理论指导和实验数据参考。     

发酵乳杆菌LFQ153胞外多糖对RAW264.7巨噬细胞氧化损伤的保护作用

为探究发酵乳杆菌LFQ153胞外多糖(exopolysaccharides,EPS)对RAW264.7巨噬细胞氧化损伤的保护作用与机制,该研究以DPPH自由基和羟自由基清除能力研究EPS的体外抗氧化水平.通过脂多糖(lipopo-lysaccharide,LPS)刺激RAW264.7巨噬细胞建立氧化损伤模型,以抗氧化酶...     

沙棘降解多糖结构表征和功能特性研究

为评价H₂O₂降解对沙棘多糖(sea buckthorn polysaccharides, SBP)结构和性质的影响,采用H₂O₂联合Fe²⁺法降解SBP,研究沙棘降解多糖(sea buckthorn degraded polysaccharides, SBDP)的分子质量、单糖组成、粒径、结构特征和抗氧化能力。结果表明,SBDP分子质量(2.902×10⁴Da) 显著低于SBP(3.016×10⁵Da)。离子色谱分析表明, SBDP和SBP均由相同的单糖(岩藻糖、鼠李糖、阿拉伯糖、半乳糖、葡萄糖、甘露糖和半乳糖醛酸)以不同的物质的量比组成。红外光谱及核磁共振波谱证实,SBDP和SBP具有相似的结构特征。与SBP相比,SBDP溶解度提高20.72%,具有更好的吸湿性和保湿性,表观黏度(5.0mg·mL-1)更低,具有剪切稀化行为。与SBP相比,SBDP表现出较高的抗氧化活性, DPPH·、ABTS⁺·及羟基自由基清除率分别为89.44%±0.12%、96.09%±0.22%和73.25%±1.16%。 H₂O₂联合Fe²⁺处理显著降低了SBP分子质量,增强了SBP的功能特性和抗氧化活性,研究旨在为拓展SBP在食品领域的应用提供理论参考。     

海参蛋白肽对H_2O_2诱导RAW264.7细胞氧化损伤的保护作用

以海参为原料,研究海参蛋白肽的抗氧化性以及对H2O2诱导RAW264.7巨噬细胞氧化损伤的保护效果和作用机制。以清除羟自由基(·OH)能力、Fe2+螯合能力和Fe3+还原能力为指标,评价海参蛋白肽的体外抗氧化活性。以H2O2刺激RAW264.7巨噬细胞建立氧化损伤细胞模型,采用2′,7′-二氯荧光黄双乙酸盐(DCFH-DA)荧光探针法测定细胞活性氧(ROS)水平,四甲基偶氮唑盐(MTT)法测定细胞活力,实时荧光定量PCR测定细胞血红素氧合酶-1(HO-1)m RNA表达水平。结果表明,海参蛋白肽能够清除·OH,具有Fe2+螯合能力和Fe3+还原能力,海参蛋白肽的这种体外抗氧化能力呈现浓度依赖效应。海参蛋白肽显著降低氧化损伤RAW264.7巨噬细胞ROS水平和提高氧化损伤细胞活力(P0.05)。而且,海参蛋白肽显著提高巨噬细胞内HO-1 m RNA表达(P0.05),HO-1抑制剂锌原卟啉IX(Zn PPIX)部分逆转海参蛋白肽对氧化损伤巨噬细胞活力的促进作用。这些结果说明,海参蛋白肽通过上调RAW264.7巨噬细胞HO-1 m RNA表达水平,发挥对巨噬细胞氧化损伤的保护作用。     

基于罗丹明B荧光猝灭构建食用油脂过氧化值检测模型

以经典碘量法为基础,构建油脂过氧化值荧光分析新方法。在含有KI的醋酸-醋酸钠缓冲介质中,罗丹明B(RhB)在580 nm处有一个荧光峰,当有油脂存在时,油脂过氧化物可将I_^-氧化为可溶性碘(I_3^-),I_3^-对罗丹明B具有荧光猝灭作用,使荧光信号强度减弱甚至消失。在模拟状态下,以H₂O₂标准溶液作过氧化物对照品,基于“H₂O₂-I_^--RhB”反应体系建立了油脂过氧化值检测模型,油脂加入前后荧光强度变化量(△F)体现了油脂过氧化值,微量取样可最大限度减少有机溶剂干扰,油脂过氧化物最低检出量为0.06 mmol/kg。罗丹明B荧光猝灭模型用于油脂过氧化值测定,具有准确、操作简便、检出量低等优点。     

乳酸菌发酵接骨木果汁降血糖与抗氧化活性机理

为探究乳酸菌发酵对接骨木果汁抗氧化活性的影响,通过测定DPPH自由基、羟自由基和超氧阴离子自由基清除率和细胞抗氧化实验比较接骨木果汁发酵前后抗氧化活性的变化。实验结果显示,接骨木果汁发酵后对DPPH自由基、羟自由基和超氧阴离子自由基的清除能力提高,对α-葡萄糖苷酶和α-淀粉酶的抑制能力也增加,证明发酵果汁具有降血糖活性。HepG2细胞分别使用发酵前后酚类物质预处理24 h后再用H₂O₂刺激,发现HepG2细胞中总抗氧化能力（T-AOC）、过氧化氢酶（CAT）活力均高于对照组,乳酸脱氢酶（LDH）相对释放率高于空白组,但远远低于对照组,细胞中活性氧的积累降低,并且血红素加氧酶-1（HO-1）、醌氧化还原酶-1（NQO1）以及谷氨酸半胱氨酸连接酶催化亚基（GCLC）相关抗氧化酶的基因表达量在仅用H₂O₂处理后的HepG2细胞中降低,而在发酵前后分别经质量浓度为200 μg/mL和300 μg/mL酚类物质预处理的HepG2细胞中明显提高,表明接骨木果汁中的酚类化合物降低了H₂O₂对HepG2细胞的氧化损伤程度。由此可见,接骨木果汁发酵前后抗氧化能力发生变化的原因可能是在酚类化合物的作用下提高了HepG2细胞中HO-1、NQO1和GCLC的基因表达水平,因此说明果汁发酵后提高了对细胞的保护作用。     

新型过氧化氢稳定剂的制备及性能研究

本研究以马来酸-丙烯酸共聚物（MA-AA）为主体稳定剂,与螯合型助剂复合,制备了新型过氧化氢（H₂O₂）稳定剂,通过测定新型H₂O₂稳定剂对金属离子的螯合值、H₂O₂分解率及进行化机浆H₂O₂漂白实验,研究新型H₂O₂稳定剂对H₂O₂漂白的稳定性能,并与进口稳定剂进行比较。结果表明,新型H₂O₂稳定剂对Fe³⁺、Mg²⁺、Mn²⁺、Ca²⁺的螯合能力分别达262.3、105.2、141.4、160.3 mg/g;在模拟国内4个地区水质中不同金属离子含量条件下,新型H₂O₂稳定剂能够有效抑制H₂O₂分解,具有与进口产品相当的稳定能力。在纸浆漂白工艺条件下,新型H₂O₂稳定剂在低用量时,对桉木化机浆、杨木化机浆、蔗渣化机浆和芦苇化机浆的漂白均有良好的稳定效果。     

金银花叶黄酮体外抗氧化能力及对H2O2诱导RAW264.7巨噬细胞损伤的保护作用

目的：研究金银花叶黄酮的体外抗氧化能力和对H2O2诱导RAW264.7巨噬细胞损伤的保护作用。方法：金 银花叶粉经提取纯化后得到金银花叶黄酮粉,以抗坏血酸为阳性对照,测定金银花叶黄酮的总还原力,对羟自由 基、超氧阴离子自由基及1,1-二苯基-2-三硝基苯肼自由基的清除能力。体外培养RAW264.7巨噬细胞,实验分为空 白组、模型组、对照组和金银花叶黄酮低、中、高剂量组,用H2O2诱导损伤RAW264.7细胞,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丙二醛、谷胱甘肽含量及超氧化物歧化酶、乳酸脱氢酶活力。结果：金银 花叶黄酮的总还原力及对各自由基的清除能力较强,并在足够质量浓度下等同于对照品抗坏血酸。金银花叶黄酮呈 剂量依赖性保护H2O2引起的RAW264.7细胞的损伤,降低细胞及细胞培养液中丙二醛含量,提高超氧化物歧化酶活力 及谷胱甘肽含量,提高细胞内乳酸脱氢酶活力。结论：金银花叶黄酮抗氧化能力较强,可修复H2O2诱导的RAW264.7 巨噬细胞的损伤,其作用可能与调节细胞氧化还原系统、清除自由基、提高细胞内抗氧化酶系的活力有关。     

Nano-CeO2 exhibits adverse effects at environmental relevant concentrations

Ceria nanoparticles (nano-CeO(2)), due to their widespread applications, have attracted a lot of concern about their toxic effects on both human health and the environment. The present work aimed to evaluate the in vivo effects of nano-CeO(2) (8.5 nm) on Caenorhabditis elegans (C. elegans) at environmental relevant concentrations (molar concentrations ranging from 1 nM to 100 nM). The results indicate that nano-CeO(2) could induce ROS accumulation and oxidative damage in C. elegans, and finally lead to a decreased lifespan. The most surprising thing is that the mean lifespan of nematodes was significantly decreased by 12% even at the exposure level of 1 nM (p < 0.01). In vitro tests suggest that the ability of nano-CeO(2) to catalyze ROS generation was involved in the mechanism for its toxicity to C. elegans. To our best knowledge, this is the first case in which nanoparticles exhibit adverse effects on organisms at such low concentrations (1nM-100 nM). So, our findings indicate the importance of nanotoxicological investigations at environmentally relevant concentrations and will attract more attentions on the risks of NPs exposure.     

Temperature and water activity effects on production of T-2 and HT-2 by Fusarium langsethiae strains from north European countries

This study has examined the effect of ecophysiological factors, water activity (a_w, 0.995-0.90) and temperature (10-37 °C), on the T-2 and HT-2 toxins production by Fusarium langsethiae. Two dimensional profiles for optimum and marginal conditions have been built for two strains from each of four northern European countries (UK, Norway, Sweden, Finland) on an oat-based medium. This showed that the optimum a_w and temperature conditions for T-2 + HT-2 production was between 0.98-0.995, and 20-30 °C respectively. Kruskal-Wallis analysis of ranks showed a statistically significant differences between the different a_w levels examined (P < 0.001) but no significant effect of the temperatures examined. The ratio of HT-2/T-2 was investigated and non-uniform distribution of HT-2 toxin was found under different ecological conditions. No statistically significant differences were found for the mean toxin production between strains from the different countries. Intra-strain differences in toxin production was only found for those from Finland (P-value = 0.0247). The growth/no growth and toxin/no toxin conditions in relation to a_w x temperature have been constructed for the first time. This knowledge will be useful in developing prevention strategies to minimise T-2 and HT-2 toxin contamination by strains of F. langsethiae on important small grain cereals.     

杭锦2#土脱色剂的制备及其对植物油脱色性能的研究

通过对内蒙古杭锦#土进行活化处理,制备了低成本植物油脱色剂.研究了活化盐酸浓度、焙烧温度、脱色温度、油土比、脱色时间等对脱色效果的影响,并与市售活性白土进行了比较,研究结果表明,杭锦2#土活化的条件为:10%盐酸105℃下活化10 h,过滤、洗涤至pH为5,脱水烘干,300℃焙烧2 h,其对植物油脱色的最佳条件:油土比100∶(1.5～2),脱色温度90～95℃,脱色时间30 min;杭锦2#活性白土的脱色性能超出了市售活性白土,可作为一种新型的植物油脱色剂应用于植物油的精炼脱色.     

Identification of antioxidant peptides derived from egg-white protein and its protective effects on H2O2-induced cell damage

To identify novel antioxidant peptides from egg-white protein and investigate antioxidant mechanism, the hydrolysate of egg-white protein was purified by ultrafiltration and a Sephadex G-15 column. The peptides VYLPR, EVYLPR, VEVYLPR and VVEVYLPR were identified from the fraction with the highest antioxidant activity. The Results showed that the peptide VYLPR exhibited the strongest protective effect on HEK-293 cells. The viability of cells recovered to 97.45 ± 1.98% with pre-treatment of 20 μm VYLPR. We further investigated antioxidant mechanism. The results showed VYLPR could inhibit lipid peroxidation process, maintain cell membrane integrity, inhibit intracellular LDH activity, reduce MDA content, and improve the activity of antioxidant enzyme T-SOD and GSH-Px. This work could help researchers in understanding antioxidant mechanism of peptides and also contribute to developing functional egg-white product.     

Low pressure CO2 storage of raw milk: microbiological effects

The effects of holding raw milk under carbon dioxide pressures of 68 to 689 kPa at temperatures of 5, 6.1, 10, and 20°C on the indigenous microbiota were investigated. These pressure-temperature combinations did not cause precipitation of proteins from the milk. Standard plate counts from treated milks demonstrated significantly lower growth rate compared with untreated controls at all temperatures, and in some cases, the treatment was microcidal. Raw milk treated with CO₂ and held at 6.1°C for 4 d exhibited reduced bacterial growth rates at pressures of 68, 172, 344, and 516 kPa; and at 689 kPa, demonstrated a significant loss of viability in standard plate count assays. The 689-kPa treatment also reduced gram-negative bacteria and total Lactobacillus spp. The time required for raw milk treated at 689 kPa and held at 4°C to reach 4.30 log₁₀ cfu/mL increased by 4 d compared with untreated controls. Total coliform counts in the treated milk were maintained at 1.95 log₁₀ cfu/mL by d 9 of treatment, whereas counts in the control significantly increased to 2.61 log₁₀ cfu/mL by d 4 and 2.89 log₁₀ cfu/mL by d 9. At d 8, Escherichia coli counts had not significantly changed in treated milk, but significantly increased in the control milk. Thermoduric bacteria counts after 8 d were 1.32 log₁₀ cfu/mL in treated milk and 1.98 log₁₀ cfu/mL in control milk. These data indicated that holding raw milk at low CO₂ pressure reduces bacterial growth rates without causing milk protein precipitation. Combining low CO₂ pressure and refrigeration would improve the microbiological quality and safety of raw milk and may be an effective strategy for shipping raw single strength or concentrated milk over long distances.     

A study of carboxylic acids and nano-TiO2 effects on stress relaxation of cotton fabrics

This study presents an evaluation on stress relaxation of cotton fabrics before and after performing the finishing process. The process includes a series of treatments on fabric samples through the Pad-dry curing method. A group of organic acids along with a proportion of catalyst and co-catalyst mixture constituted the treatment agents. Stress relaxation behavior of untreated and treated samples was assessed along two different directions of weft and warp using stress relaxation tester. In addition, an Italian Mesdan tensile tester was applied to measure physical and mechanical properties such as elongation, strength, Poisson’s ratio, and shear modulus. In the mean time scanning electron microscopy was applied to consider surface of samples before and after treatments. The results prove that the stress relaxation of treated samples has shown reasonably acceptable values when compared with those obtained for untreated one. Furthermore, the curve fitting of Maxwell’s model over the experimental data also justified that an interlaced model is more appropriate for explaining the stress relaxation in cotton fabrics. Beside the result of stress relaxation, Poisson’s ratio, and shear modulus illustrated remarkable increments. On the other hand, a reverse trend was observed for tensile properties in both directions. Orthotropic feature evaluation of fabrics toward both the direction of warp and weft also infers different response of stress relaxation in each direction.     

Cryogelation of cereal β-glucans: structure and molecular size effects

The effects of molecular size and fine structure of mixed-linkage cereal (1→3), (1→4) β- -glucans (β-glucans) on their cryogelation behavior were investigated. Values of apparent molecular weight (M_w) for oat β-glucans ranged between 65 and 200×10³, whereas the respective values for both barley and wheat β-glucan preparations were about 200×10³. The fine structure of cereal β-glucans, as assessed by high-performance anion-exchange chromatography of the cellulosic oligomers released by the action of lichenase, revealed differences in the relative amounts of 3-O-β-cellobiosyl- -glucose (DP3) and 3-O-β-cellotriosyl- -glucose (DP4) units only among the different genera of cereals; the weight percent of DP3 units estimated as 67.1, 63.3, and 55.3–55.8% for wheat, barley, and oat β-glucans, respectively. Aqueous β-glucan solutions (1–3% w/v) were subjected to 12 freezing (−18 °C for 24 h) and thawing (5 °C for 24 h) cycles. The phenomenological appearance of the gelled materials obtained after this process as well as the yield of cryostructurates were influenced by the initial solution concentration, the number of freeze–thaw cycles, as well as by the molecular features of the β-glucans. Such effects were unraveled by studying the cryogelation process with differential scanning calorimetry (DSC), small strain dynamic rheometry, and large deformation mechanical measurements. For the cereal β-glucan cryogels the storage modulus, G′, increased and the tan δ decreased with decreasing polysaccharide molecular size and with increasing initial solution concentration, number of freeze–thaw cycles, and trisaccharide segments in the polymeric chains. The apparent melting enthalpy values (ΔH) of β-glucan cryostructurates, as determined from the DSC endothermic peaks, increased with decreasing molecular size and with increasing amount of cellotriose units, but they were independent of the number of freeze–thaw cycles. The DSC melting temperature of the gel network was found to increase with the molecular size and amount of DP3 units of β-glucans. Moreover, large deformation mechanical tests (compression mode) revealed an increase in strength of cereal β-glucan cryogels with increasing molecular size and decreasing trisaccharide units in the polysaccharide preparation.     

Essential rosemary oil protects testicular cells against DNA-damaging effects of H2O2 and DMNQ

Rosemary oil (RO) is popular in the Mediterranean region as a culinary additive which has the ability to protect delicate organs such as liver, brain and heart. We examined the effect of RO consumption on resistance of rat testicular cells (TCs) against DNA-damaging effects of the oxidative agents H₂O₂ and DMNQ and on the activity of the antioxidant enzymes glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). DNA lesions were detected by conventional and modified comet assay and the activities of GSH-Px and SOD were measured spectrophotometrically. Since TCs represent a mixture of haploid, diploid and tetraploid cells, we used flow cytometry for their differentiation and calculation of DNA-damaging effects of H₂O₂ and DMNQ in cells of different ploidy. The results showed that the oxidative DNA lesions were significantly reduced in TCs from rats administered RO; however, the activity of antioxidant enzymes did not differ in TCs from control and RO-supplemented rats.