丰城鸡血藤黄酮提取物清除自由基活性研究

本文考察了丰城鸡血藤不同提取物对.DPPH、O2-.和.OH清除活性,分别采用紫外可见分光光度法、邻苯三酚自氧化法和Fenton反应-邻菲罗啉显色法,测定受试物对.DPPH、O2-.和.OH的清除活性。实验结果表明受试物对.DPPH清除活性较强,对O2-.的清除活性次之,对.OH的清除活性较弱。丰城鸡血藤不同提取物黄酮组成和含量存在差异,其自由基清除活性也有所不同,提示它们的自由基清除作用机制和生物活性可能存在差异。     

荸荠皮多糖体外清除自由基活性的研究

采用DPPH自由基法、邻苯三酚自氧化法和水杨酸法分别表征了荸荠皮多糖清除DPPH自由基(DPPH.)、超氧阴离子自由基(O2-.)和羟基自由基(.OH)的能力。结果显示,脱蛋白和未脱蛋白荸荠皮多糖具有清除自由基的活性,但该活性明显低于茶多酚。脱蛋白多糖清除DPPH.的能力高于未脱蛋白多糖,其清除50%DPPH.的作用质量浓度(EC50)分别为50.26 mg.L-1和76.22 mg.L-1。两种多糖清除.OH和O2-.的能力相当,其EC50(g.L-1)分别为0.118和0.124以及10.87和9.53。     

木犀草素-锡(Ⅱ)配合物的合成、表征及抗氧化活性研究

木犀草素与金属离子有较强的配位能力,形成配合物后,活性会发生变化,因此研究了木犀草素与锡(Ⅱ)配合物的合成及其抗氧化活性。采用紫外可见分光光度法、红外光谱法和核磁共振氢谱法对配合物的结构进行表征,并通过DPPH自由基法和邻二氮菲-Fe2+法分别测定了木犀草素-锡(Ⅱ)配合物对DPPH自由基和羟基自由基(.OH)的清除作用。结果表明,木犀草素与锡(Ⅱ)发生配位的位点在5-OH～4-C=O位和3’,4’-OH位,木犀草素-锡(Ⅱ)配合物具备一定的清除DPPH自由基和.OH自由基的性能,但是由于二价锡离子与木犀草素分子中的活性位点(酚羟基)发生了配位络合,所以清除上述自由基的性能较木犀草素均有所降低。     

金樱子总黄酮体外抗氧化活性的研究

本文研究了金樱子总黄酮(RLTF)体外清除自由基的能力,并观察其对过氧化氢诱导损伤的人脐静脉内皮细胞(HUVEC)抗氧化作用的影响。采用邻苯三酚自氧化法、水杨酸法、DPPH法分别测定RLTF对超氧阴离子自由基(O-·2)、羟自由基(·OH)、二苯代苦味酰基自由基(DPPH·)的清除率;Hoechst染色法分析各组细胞凋亡情况;MTT法测定细胞活力;分光光度法检测各组细胞中SOD、CAT、GSH-Px活性。结果显示,在20~200μg范围内,随着样品加入量增大,RLTF对·OH和DPPH·的清除率逐渐增大,而对O-·2的清除率则是先增大后减少;RLTF对O-·2的清除作用偏低,对·OH的清除率与芦丁相当,对DPPH·的清除能力则强于芦丁而弱于Vc。Hoechst染色观察结果表明RLTF预处理细胞后,能明显提高细胞的抗凋亡作用。与H2O2损伤组比较,不同浓度RLTF预处理组的细胞活力均显著升高(P0.01);不同浓度RLTF预处理组细胞中的SOD、CAT和GSH-Px活性均明显增加(P0.01),且呈剂量依赖性。上述结果表明,RLTF具有较强的自由基体外清除能力,能有效提高氧化损伤HUVEC细胞中SOD、CAT、GSH-Px的酶活性,其可能通过清除细胞内自由基和提高细胞抗氧化酶活性来提高细胞的抗氧化活性。     

瓦宁木层孔菌中多酚和黄酮类成分分离及清除自由基活性的研究

采用硅胶和反相C18柱层析方法,首次从瓦宁木层孔菌中分离得到了5个化合物,运用NMR波谱法分析和鉴定为樱花亭、7-甲氧基二氢莰非素、二氢莰非素、4-(3,4-二羟苯基)-3-丁烯-2-酮、hispolon。并通过建立体外二苯基苦味酰基苯肼自由基（·DPPH）、超氧阴离子自由基（·O2?）以及羟自由基（·OH）发生体系,研究了5个化合物对·DPPH、·OH和·O2?的清除作用。结果表明当浓度达到100μg/mL时,化合物4-(3,4-二羟苯基)-3-丁烯-2-酮和hispolon对·DPPH清除率分别为92%和93%,对·OH的清除率分别为90%和95%,而对·O2?的清除率分别为70%和77%,略低于清除·DPPH和·OH的能力;二氢莰非素对·O2?自由基的清除率为39%,强于清除·OH和·DPPH的能力;而樱花亭和7-甲氧基二氢莰非素对3种自由基的清除率均低于30%。2个多酚类化合物清除自由基的能力均强于3个黄酮类化合物。5个化合物清除自由基能力均表现出一定的浓度依赖性。     

库克诺你果汁提取物体外清除自由基及抗氧化活性研究

本文对诺你果汁多糖、乙醇溶出物和乙酸乙酯萃取物体外对超氧阴离子(O2·)、羟自由基(·OH)、DPPH和脂质过氧化(LPO)的抑制作用进行了研究。超氧阴离子(O2·)由邻苯三酚自氧化产生;羟自由基(·OH)由Fenton反应产生;利用Fe2 诱发卵黄脂蛋白产生丙二醛(MDA),TBA法测定。所有测定均为分光光度法。结果表明,与已知抗氧化剂L抗坏血酸相比,乙醇溶出物和乙酸乙酯萃取物均有明显的捕捉自由基和抗氧化能力,而多糖捕捉自由基和抗氧化能力很低,且对O2·没有抑制作用,反而会增加其生成速度。     

不同种竹笋及笋壳提取物抗氧化活性的研究

采用醇提法,分别对毛竹、麻竹、雷竹的竹笋及笋壳进行醇提,并对醇提物进行抗氧化活性测定.对DPPH·、OH·、O2-·自由基的清除作用分别通过分光光度法、邻二氮菲法、邻苯三酚自氧化法进行测定,相对还原能力、总抗氧化能力的测定则采用普兰士蓝反应法和FRAP法.结果表明:不同种的竹笋及笋壳的醇提物含量与自由基清除能力、相对还...     

青海沙棘果粉抗氧化活性的研究

为了深入了解青海沙棘果粉的品质,助其实现规模化生产,从1,1-二苯基苦基苯肼自由基(DPPH·)体系、羟基自由基(·OH)体系、超氧阴离子自由基(O-2·)体系和亚硝酸盐(NO-2)的清除效果方面着手,研究了其体外清除自由基活性。结果表明,青海沙棘果粉对DPPH·、·OH、O-2·和NO-2均有清除作用,且对DPPH·、·OH的清除能力优于O-2·和NO-2。     

红花寄生叶3种溶剂提取物清除自由基活性

采用4种方法测定了红花寄生(寄主桑树)叶的水、80%甲醇和80%丙酮提取物对自由基的清除活性,以芦丁和BHT为对照品。结果表明,3种提取物均具有较强的自由基清除能力,且表现出不同程度的量效依赖关系;在3种溶剂提取物中,80%甲醇提取物清除.OH和O2-.活性最强,半清除率浓度ρ(SC50)分别为0.212、0.139 mg/mL,而80%丙酮提取物则清除DPPH.和ABTS.+活性最强,ρ(SC50)分别为0.198、0.580 mg/mL。此外,3种溶剂提取物经酸水解后,HPLC均检出槲皮素和山奈酚等2种黄酮醇苷元,其含量范围分别为39.90～73.03 mg/g、4.82～9.19 mg/g间。可见,槲皮素及其苷类衍生物是红花寄生清除自由基活性的主要作用成分。     

红车轴草总黄酮体外清除自由基作用的研究

通过Fenton 反应产生·OH,邻苯三酚自氧化产生O·-2模型,研究了红车轴草总黄酮体外清除自由基的作用.结果显示红车轴草总黄酮在6.25～200 mg/mL范围内具有清除Fenton 反应产生·OH的作用,在6.25～100 mg/mL浓度范围内对邻苯三酚自氧化产生的O·-2具有清除作用,二者均呈明显的量效关系,对·OH和O·-2半数清除浓度分别为44.06 和54.57 mg/mL.     

Embryo and Endosperm Function and Failure inSolanumSpecies and Hybrids

Although the importance of the endosperm as a food store inmany angiosperm seeds is well known, its significance duringearly embryogenesis has been neglected. In many interspecifichybrids, and in some other situations, embryos do not developfully and abort. It has often been stated that this is causedby the endosperm failing to conduct sufficient nutrients tothe embryo, but seldom has it been suggested that the endospermactively controls most of the early stages of morphogenesisof the embryo. Information gleaned from a broad survey of theliterature, combined with additional evidence presented here,obtained fromSolanum incanumand interspecific hybrids, indicatethat the endosperm is dynamic and very active in regulatingearly embryo development. This requires highly integrated geneticcontrol of rapidly changing metabolism in the endosperm. Ininterspecific hybrids, lack of coordination may cause unbalancedproduction of growth regulating substances by the endospermand hence abortion of the embryo, or even unregulated productionof nucleases and proteases resulting firstly in autolysis ofthe endosperm and then digestion of the embryo. The endospermmay thus serve to detect inappropriate hybridization of speciesor ploidy levels and so prevent waste of resources by producingseeds that would result in sterile hybrids or unthrifty subsequentgenerations. This discriminatory function of the endosperm hasdiminished during evolution and domestication of the crop plantSolanummelongenaL.Copyright 1998 Annals of Botany Company Solanum, embryo morphogenesis, endosperm, hybrid, seed development.     

Pragmatic Women and Body Politics and Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific

Pragmatic Women and Body Politics. Margaret Lock and Patricia A. Kaufert. eds. Cambridge, UK: Cambridge University Press, 1998. xii +364 pp.
Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific. Kalpana Ram and Margaret Jolly. eds. Cambridge, UK: Cambridge University Press, 1998. xiv. 305 pp.     

HIFs and tumors--causes and consequences

For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed.     

环腺苷酸应答元件结合蛋白与学习记忆

环腺苷酸(cAMP)应答元件结合蛋白(cAMP response element binding protein,CREB)是一种核转录因子,可与cAMP反应元件结合,调节基因转录,具有调节精子生成,昼夜节律,学习记忆等功能.近年来关于其在学习记忆中的作用成为医学研究热点.CREB是神经元内多条信息传递途径的汇聚点,参与长时记忆形成和突触可塑性.长时记忆(long-term memory)形成需依赖CREB介导的基因转录,干扰或抑制CREB活性可破坏长时记忆.长时程增强(long-term potentiation,LTP)是研究学习记忆的理想模型,在LTP诱导和维持过程中均可观察到CREB活性持续升高.但增龄过程中,海马CREB活性下降,影响学习记忆功能,与许多神经退行性疾病发生有关.     

Morphological and constitutional features and self-esteem in children and adolescents

Studies of human constitution and mental features are traditionally among the main concepts of anthropological research. In this research, we attempted to discover connections between morphological and constitutional features and self-esteem in children and adolescents. Such a connection was discovered in some studied age groups. The obtained results could serve as a basis for further studies in this field.