自由基与啤酒老化

从活性氧、自由基的角度对啤酒老化的实质进行了诠释,并介绍了啤酒羟基自由基的检测方法及其在啤酒内源抗氧化能力评价中的应用.     

自由基对啤酒风味老化的影响与控制分析

啤酒自由基的理论研究与ESR等分析技术的应用为啤酒老化的研究和改进提供了方法和思路.本文对自由基及其与啤酒老化的影响进行了阐述,同时也对一些主要的内源抗氧化剂的影响与作用进行了分析.     

番茄红素纳米分散体体外清除活性氧自由基研究

采用乳化-蒸发工艺（超声乳化）制备了番茄红素纳米分散体,用分光光度法研究了番茄红素纳米分散体体外清除活性氧自由基（过氧化氢、羟自由基）的作用,并与溶于四氢呋喃的番茄红素进行比较。结果表明,番茄红素纳米分散体对这两种自由基均有不同程度的清除作用,且均呈现一定的量效关系;在相同浓度下,其清除能力均强于番茄红素四氢呋喃溶液,其中对过氧化氢清除能力远远高于番茄红素四氢呋喃溶液。      

黑莓红色素对活性氧自由基和亚硝基的清除作用

黑 莓 红 色 素 对 光 照 核 黄 素 产 生 的 O ·和 Fenton 反 应 产 生 - 2 的·O H 及 N O 均 具 有 很 强 的 清 除 作 用 ,且 在 一 定 浓 度 范- 2 围 内 随 浓 度 的 增 大 而 增 强 。 在 试 验 浓 度 范 围 (0.1～2.5m g/ m L)内 ,黑 莓 红 色 素 对 O ·、·O H 及 N O 的 最 大 清 除 率22分 别 可 达 到 96.27%、93.58%和 98.94%。 因 此 ,黑 莓 红 色 素 还 是 一 种 优 良 的 天 然 自 由 基 清 除 剂 和 N O 清 除 剂 。     

黑莓红色素对活性氧自由基和亚硝基的清除作用

黑 莓 红 色 素 对 光 照 核 黄 素 产 生 的 O ·和 Fenton 反 应 产 生 - 2 的·O H 及 N O 均 具 有 很 强 的 清 除 作 用 ,且 在 一 定 浓 度 范- 2 围 内 随 浓 度 的 增 大 而 增 强 。 在 试 验 浓 度 范 围 （0.1～2.5m g/ m L）内 ,黑 莓 红 色 素 对 O ·、·O H 及 N O 的 最 大 清 除 率22分 别 可 达 到 96.27%、93.58%和 98.94%。 因 此 ,黑 莓 红 色 素 还 是 一 种 优 良 的 天 然 自 由 基 清 除 剂 和 N O 清 除 剂 。      

自由基、微量元素与人体健康

探讨了自由基对人体的危害，阐述了微量元素对健康的作用。     

马尾松花粉多糖硫酸酯化前后清除活性氧自由基能力的比较

目的：对松花粉多糖硫酸酯化前后清除超氧阴离子自由基（O2^-·）和羟自由基（·OH）的作用进行比较。方法：用荧光分光光度法检测松花粉多糖及其硫酸酯体外清除O2^-·和·OH的作用。结果：松花粉多糖硫酸酯化前后对活性氧自由基均有一定的清除作用,酯化后对O2^-·的清除能力增强（P〈0．01）,对·OH的清除能力降低（P〈0．01）。     

葛仙米藻红蛋白体外抗活性氧自由基作用的研究

葛仙米以其资源稀少、营养价值丰富,独特的生物活性和药理作用而引起人们广泛地关注。为探讨葛仙米中的生物活性成分,本文以野生葛仙米藻红蛋白为研究对象,在系统研究葛仙米藻红蛋白的提取、分离和纯化的基础上,采用微弱化学发光法,研究了葛仙米藻红蛋白清除氧自由基的能力。结果表明:清除氧自由基的能力为:粗提物>藻红蛋白>藻蓝蛋白;葛仙米藻红蛋白清除氧自由基的能力为:H2O2自由基的清除率>·OH自由基的清除率>O2·自由基的清除率。     

羟化赖氨酸清除活性氧自由基能力的研究

在竹叶及其提取物中检出了一种特殊的非蛋白氨基酸δ－ＯＨ－Ｌｙｓ，为了解其生物学意义，用化学发光法和电子自旋共振法（ＥＳＲ）对δ－ＯＨ－Ｌｙｓ和Ｌｙｓ清除超氧阴离子自由基（Ｏ２－）的能力作了比较，结果表明赖氨酸在δ位羟化以后，抗活性氧自由基的活性有了显著提高。     

活性氧的生成与健康和疾病关系研究进展

从历史上看,活性氧（reactive oxygen species,ROS）被认为只引起细胞损伤及生理功能障碍,ROS及其氧化损伤与多种疾病,包括神经退行性疾病、糖尿病、癌症和过早衰老相关。然而,近年来,越来越多的证据显示,ROS对健康至关重要。在生理条件下,低水平ROS的生成被认为是信号分子。另一方面,ROS的过度生成,与ROS缓冲系统的功能障碍相关,会导致慢性疾病的发展。因此,ROS的慢性释放参与许多疾病的发病。而且,ROS生成过量诱导生物分子的氧化损伤,进而导致衰老、癌症和许多其他疾病。ROS已经参与100多种疾病的发生,包括威胁人类健康的重大疾病癌症、心血管疾病、糖尿病、神经退行性疾病（如帕金森病和阿尔茨海默病）、获得性免疫缺陷综合征、中风和衰老的发生。本文综述了氧的出现与需氧真核生物的进化、ROS的种类、ROS的生理病理多效性、机体内主要的ROS、ROS的生成与反应、ROS与线粒体氧化磷酸化、细胞凋亡、免疫防御和炎症、肿瘤等方面的最新进展,鉴于ATP和ROS对生命的重要性,提出,调控线粒体氧化磷酸化实现ATP与ROS生成的平衡将是健康的关键。     

Chemistry and reactions of reactive oxygen species in foods

Reactive oxygen species (ROS) are formed enzymatically, chemically, photochemically, and by irradiation of food. They are also formed by the decomposition and the inter-reactions of ROS. Hydroxy radical is the most reactive ROS, followed by singlet oxygen. Reactions of ROS with food components produce undesirable volatile compounds and carcinogens, destroy essential nutrients, and change the functionalities of proteins, lipids, and carbohydrates. Lipid oxidation by ROS produces low molecular volatile aldehydes, alcohols, and hydrocarbons. ROS causes crosslink or cleavage of proteins and produces low molecular carbonyls from carbohydrates. Vitamins are easily oxidized by ROS, especially singlet oxygen. The singlet oxygen reaction rate was the highest in ss-carotene, followed by tocopherol, riboflavin, vitamin D, and ascorbic acid.     

油茶总皂甙抑菌活性及清除活性氧能力初步研究

用溶剂法提取油茶饼中油茶总皂甙,经柱层析制备标准品标定有效成分含量为82.5%。以油茶皂甙为材料对枯草杆菌、大肠杆菌、金黄色葡萄球菌进行抑菌试验,结果表明均有抑制作用;其中对枯草杆菌和金黄色葡萄球菌抑制作用较强,20%浓度对三种细菌均具有致死作用,抑菌圈直径大小与油茶总皂甙浓度呈正相关;且初步测定油茶总皂甙清除活性氧能力强于维生素C。     

The etiology of oxidative stress in the various species of animals,a review

Oxidative stress is the consequence of an imbalance of pro‐oxidants and antioxidants leading to cell damage and tissue injury. The exhaustion of antioxidant systems is one of the reasons for the occurrence of oxidative stress, which results in avalanche production of reactive oxygen species (ROS) or free radicals. High oxidative stress is common in organs and tissues with high metabolic and energy demands, including skeletal and heart muscle, liver and blood cells. Stress arises in animals in response to unavoidable or adverse environmental conditions. In the external environment, which affects the body of the cow, there are four main groups of stressors: physical, chemical, biological and psychological. Physical stressors include fluctuations in ambient temperature as well as mechanical injuries. High ambient temperature is one of the factors affecting the productivity of cows. Biological stressors are conditioned by errors and irregularities in habits. Both of these phenomena have an adverse impact on both the resistance of animals and fertility and are the etiological agent of oxidative stress. Various mechanisms may be responsible for metal‐induced oxidative stress: direct or indirect generation of ROS, depletion of glutathione and inhibition of antioxidant enzymes are well known for all redox‐active and redox‐inactive metals. © 2014 Society of Chemical Industry     

Utilizing hydroglycolic extract from myrobalan fruits to counteract reactive oxygen species

The hydroglycolic (HG) extract from 70% propylene glycol (PG) extraction of myrobalan fruits showed the most appreciable antioxidant efficiency towards 1,1-diphenyl-2-picrylhydrazyl (DPPH) in comparison to the extracts from 30, 50, 70 and 100% ethyl alcohol (EA), and 30, 50 and 100% PG . Its total polyphenols were also higher than others. The additional analysis of antioxidant power revealed that this HG extract was able to counteract the induced oxidation caused by hydrogen peroxide (H(2) O(2) ) and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). The quantification for the antioxidant capacity of the extract showed it was equivalent to 93.78 mg of 6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid (Trolox) g(-1) by 2,2'-azino-bis(3-ethylbenzthiazoline-6-suphonic acid) diammonium (ABTS) assay, and was 140.17 mg ascorbic acid (AA) equivalent g(-1) and 107.50 mg Trolox equivalent g(-1) by photochemiluminescence (PCL) assay. The incorporation of the HG myrobalan extract into lotion and sunscreen lotion rendered these products to provide the similar antioxidant power as the extract alone.     

Effect of cis-urocanic acid on bovine neutrophil generation of reactive oxygen species

Neutrophils play a fundamental role in the host innate immune response during mastitis and other bacterial-mediated diseases of cattle. One of the critical mechanisms by which neutrophils contribute to host innate immune defenses is through their ability to phagocytose and kill bacteria. The ability of neutrophils to kill bacteria is mediated through the generation of reactive oxygen species (ROS). However, the extracellular release of ROS can be deleterious to the host because ROS induce tissue injury. Thus, in diseases such as mastitis that are accompanied by the influx of neutrophils, the generation of large quantities of ROS may result in significant injury to the mammary epithelium. cis-Urocanic acid (cis-UCA), which is formed from the UV photoisomerization of the trans isoform found naturally in human and animal skin, is an immunosuppressive molecule with anti-inflammatory properties. Little is known about the effect of cis-UCA on neutrophils, although one report demonstrated that it inhibits human neutrophil respiratory burst activity. However, the nature of this inhibition remains unknown. Because of the potential therapeutic use that a molecule such as cis-UCA may have in blocking excessive respiratory burst activity that may be deleterious to the host, the ability of cis-UCA to inhibit bovine neutrophil production of ROS was studied. Further, because neutrophil generation of ROS is necessary for optimal neutrophil bactericidal activity, a response which is critical for the host innate immune defense against infection, the effects of cis-UCA on bovine neutrophil phagocytosis and bacterial killing were assayed. cis-Urocanic acid dose-dependently inhibited the respiratory burst activity of bovine neutrophils as measured by luminol chemiluminescence. Subsequently, the effect of cis-UCA on the production of specific oxygen radicals was investigated using more selective assays. Using 2 distinct assays, we established that cis-UCA inhibited the generation of extracellular superoxide. In contrast, cis-UCA had no effect on the generation of intracellular levels of superoxide or other ROS. At concentrations that inhibited generation of extracellular superoxide, bovine neutrophil phagocytosis and bacterial activity remained intact. Together, these data suggest that cis-UCA inhibits the tissue-damaging generation of extracellular ROS while preserving neutrophil bactericidal activity.     

Effect of nitric oxide on reactive oxygen species and antioxidant enzymes in kiwifruit during storage

BACKGROUND: The accumulation of reactive oxygen species (ROS) in kiwifruit can cause oxidative damage during storage. Little research has been carried out on the effects of nitric oxide (NO) on oxidative damage to kiwifruit. Therefore the aim of the present study was to evaluate the ability of 0.5, 1 and 2 µmol L^?1 NO aqueous solutions to alleviate oxidative damage to kiwifruit during storage. RESULTS: The most marked effect was obtained with 1 µmol L^?1 NO solution, which significantly reduced the accumulation of malondialdehyde, superoxide and hydrogen peroxide, delayed the decrease in vitamins C and E, maintained the content of soluble solids, inhibited the activity of lipoxygenase and peroxidase and increased the activity of superoxide dismutase and catalase in kiwifruit during storage. The 0.5 µmol L^?1 NO solution was too weak to significantly affect the content of ROS and the activity of enzymes. However, treatment with 2 µmol L^?1 NO solution promoted the accumulation of ROS, decreased the activity of antioxidant enzymes and accelerated peroxidation in kiwifruit during storage. CONCLUSION By increasing the activity of antioxidant enzymes and maintaining the content of vitamins C and E, treatment with 1 µmol L^?1 NO aqueous solution could protect kiwifruit against oxidative damage caused by ROS during storage. Copyright © 2008 Society of Chemical Industry     

三种贮藏低温对厚皮甜瓜果实活性氧产生和清除的比较

本文以厚皮甜瓜‘金红宝’为试材,研究了三种贮藏低温（3、7和9℃）对果实O-2·产生速率和H2O2含量,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽还原酶（GR）和抗坏血酸过氧化物酶（APX）活性的影响。结果表明,7℃和9℃下果实O-2·产生速率在前期（第4d）显著增加,而3℃下在后期（第12d）逐渐积累;3℃下果实的H2O2含量前期明显升高,而7℃和9℃下在中期（第8d）和后期逐渐升高。贮藏前期7℃下果实SOD、GR和APX的活性明显高于3℃和9℃处理,而3℃下果实的CAT活性最低。上述结果显示,3℃下大量的H2O2积累以及较低的抗氧化酶活性是导致甜瓜果实冷害发生的重要原因,7℃下果实维持了良好的活性氧产生和清除平衡,为厚皮甜瓜贮藏的适宜温度。      

采后蛋氨酸处理对桃果实青霉病及活性氧代谢的影响

以桃果实为材料,研究了采后不同浓度蛋氨酸处理对损伤接种桃果实扩展青霉（Penicillium expansum）病斑扩展的影响,根据病斑直径的大小筛选出能够有效抑制桃果实青霉病的最佳浓度,并以最佳浓度处理桃果实分析对活性氧代谢的影响。结果表明,15 mmol/L蛋氨酸对P.expansum的抑制效果最好,并且处理显著（p≤0.05）提高了桃果实中抗坏血酸（AsA）和还原型谷胱甘肽（GSH）含量;谷胱甘肽还原酶（GR）活性、抗坏血酸过氧化物酶（APX）活性和过氧化氢酶（CAT）活性也显著提高,同时提高了H₂O₂含量。由此表明,采后蛋氨酸处理可以通过调节桃果实体内活性氧代谢来提高果实对青霉病的抗性。