天然植物抗氧化活性成分的提取及检测方法

天然抗氧化剂能有效地清除自由基从而保护机体健康,从自然界中寻求高效、廉价、低毒的天然抗氧化剂成为目前抗氧化剂发展的一个必然趋势。总结了几种天然植物抗氧化活性成分的提取和测定方法的研究进展,为天然植物抗氧化活性成分的开发利用提供参考。     

丝兰属植物波萝花中甾族皂甙元的分离和鉴定

波萝花俗称剑麻,是一种丝兰属植物(Yucca gloriosa L.),该属植物的叶脉纤维能制成绳索,是一种经济作物.在其去纤维的废液中,经酸水解,可以提出甾族皂甙元,为合成甾体激素类药物的重要天然原料之一.     

复杂天然产物(+)-Propindilactone G的不对称全合成

<正>J.Am.Chem.Soc.2015,137,10120~10123五味子科植物是重要的药用资源植物,初步研究表明该家族的天然产物具显著的抗HIV活性.(+)-Propindilactone G是从五味子科植物合蕊五味子(Schisandrapropinqua var.propinqua)的茎藤中分离得到的降三萜天然产物.其具有独特的5/5/7/6/5环系骨架,排布有拥挤的10个手性中心,其中包括3个四级手性中心.北京大学化学与分子工程学院杨震、陈家华课题组以有机小分子催化的不对称Diels-Alder反应不对称地构建出最初的两个手性中心;通     

黄树莓叶片中黄酮类物质的提取及抗氧化性

黄酮类物质具有降血糖、降血脂、抗心律失常、抗氧化高效性与低毒性、抗衰老等生理活性1 2 。从药食两种植物中筛选出高效低毒且经济的抗氧化性强的物质 ,必将是近一步开发天然高效食品抗氧化剂的重要途径[3 5] 。黄树莓是我国北方地区小浆果树种之一 ,其中以黑龙江分布较多。黄树莓的浆果甜而芳香 ,营养丰富 ,是鲜美的生食果品 ,也可加工制成果酱、果酒、果汁和蜜饯等。它又是密源植物和药用植物 ,有止渴、痰、发汗、活血的效用。本实验以测定黄树莓叶片总黄酮含量并考察了提取物粗黄酮对猪油的抗氧化性。1　实验部分1 1　主要试剂及仪…     

中药紫珠中的二萜

紫珠(Callicarpa pedunculataR.Brown)为马鞭草科紫珠属植物,主要分布在我国南部地区,根、茎、叶及种子均可入药,有通经活血之功效[1].该属植物在中医临床上主要用于各种出血症,其中较常用的为紫珠,紫珠首载于<本草拾遗>,别名止血草,传说本药得之于某盗贼,故又称为"贼仔草"、"创伤草".经文献查阅,国内外对紫珠化学成分研究的报道较少,报道的化合物主要为黄酮、萜类成分[2-5].为了寻找紫珠中的活性成分,我们对紫珠的化学成分进行了研究.     

高分子抗氧化剂研究进展

过量自由基可造成人体的多种损伤,加速人的衰老.抗氧化剂可以清除或转化多余的自由基,对人体起到保护作用.本文从天然高分子及合成高分子两方面对抗氧化剂的研究进展进行了综述.在天然高分子抗氧化剂中,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶等的结构与功能已经较为清晰;金属硫蛋白、血红蛋白、短肽及多糖等...     

藏药无茎芥的化学成分研究

藏药无茎芥(Pegaeophyton scapiflorun(Hook.f.et Thoms)Marq.et Shaw)为十字花科(Cruciferae)无茎芥属(Pe-gaeophyton Hayeket Hand-Wazz)植物,又名单花芥、高山辣根菜,为多年生草本,主要产于云南西北部、西藏、四川、青海等地,生长于海拔3500～5400米的高山草地[1].在藏族地区,藏医用无茎芥全草内服退热、治肺咯血、并解食物中毒,外用治刀伤[2,3].无茎芥属植物只有无茎芥一种植物,该植物的化学成分研究前人未见报道.     

聚丙烯腈合成纤维的新制法

聚丙烯腈纤维又称“人造羊毛”,它的性能比天然羊毛更为优越,例如耐日光、耐辐射、耐气候变化、经日光曝露试验一年强度仍能保持80％以上,而一般的天然纤维及人造纤维不到一年甚至半年就变脆,耐热、耐酸及有机溶剂、强度高、不被虫蛀、外观似天然羊毛,但比天然羊毛轻,质地柔软,保暖似羊毛等。因此,广泛地与羊毛混纺制成纺织品,工业用耐酸滤布及制服、天幕、篷帐、鱼网等。由于单体丙烯腈制造的原料便宜易得,基本原料主要是乙炔与氰化氢,也就是用煤、电、     

中药葛根提取物中抗氧化活性成分的筛选

生物体在代谢过程中产生的氧自由基及其诱导的氧化反应对体内脂类、蛋白质、核酸、糖类等造成的氧化损害是引发炎症、心脑血管疾病、心脏疾病的重要因素~([1]),同时食用油脂和含脂食品、化妆品的酸败变质也与氧自由基氧化有关.BHT、BHA等合成抗氧化剂由于潜在的毒副作用而被许多国家禁用后,研究者开始从中草药中寻找天然、高效、低毒的抗氧化剂.     

抗氧化剂活性的电子顺磁共振（EPR）研究

抗氧化剂在化工、食品以及生命科学等领域具有重要的作用,近年来更是由于其在解决与人类健康相关问题方面所起到的重要作用而受到广泛重视。本综述较为详细地介绍了利用电子顺磁共振（EPR）技术测定抗氧化剂活性的原理和方法,系统总结了近年来在天然抗氧化剂以及合成抗氧化剂化学活性方面的EPR研究最新进展,特别是定量测定表征抗氧化活性...     

HEPT类化合物的QSAR研究

为定量结构／活性相关性研究提取了量子化学参数,拓扑指数Am,分子连接性指数^mxt及疏水性常数,同时应用正交变换和最佳变量子集算法（Leaps-and-Bonds)进行了变量压缩和选择,进而实施了多元回归分析,并由此结果进行了HEPT类化合物（1－[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine derivatives)的结构／活性关系的理论解释,进行了人工神经网络法对于该类化合物的活性预测,其结构明显好于多元回归法。     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shifts of the ring protons on the pH of the medium for a number of 4-hydroxyquinoline derivatives was studied by means of PMR spectroscopy. The dipolar and uncharged hydroxy forms exist in equilibrium in aqueous solutions. The effect of intramolecular hydrogen bonding on the character of the dependence of the chemical shift on the pH of the medium in the case of 3-piperidinomethyl-4-hydroxyisoquinoline was investigated. The possibility of the separate protonation of the ring nitrogen and the side-chain nitrogen in 3-piperidinomethyl-4-hydroxyisoquinoline was established. The distribution of the -electron density in 4-hydroxyisoquinoline is in good agreement with its chemical behavior.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1546–1549, November, 1971     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shift of the ring protons on the pH of the medium for a number of 3-hydroxyquinoline derivatives was studied by PMR spectroscopy. The regions of ionization of the molecules, which correspond to the ranges of acidic, neutral, and alkaline media, were found. In D₂O, 3-hydroxyquinoline is present only in the uncharged hydroxy form. The presence of intramolecular hydrogen bonding in 4-dimethylaminomethyl-3-hydroxyquinoline has a substantial effect on the character of the dependence of the chemical shift on the pH of the medium; the existence of separate protonation of the nitrogen atoms of the ring and the side chain of 4-dimethylaminomethyl-3-hydroxyquinoline was established. The distribution of the -electron density in the 3-hydroxyquinoline molecule is in good agreement with its chemical behavior during electrophilic substitution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1540–1545, November, 1971.     

液滴荧光传感与计算机联用技术在微量分析中的应用

通过在LS55型荧光-磷光-发光分光光度计上加装液滴产生及调节附件,采用计算机采集与分析处理数据,成功地研制了双通道液滴光化学传感装置.利用葡聚糖凝胶对复合维生素B中不同组分的选择性吸附来达到分离与同时检测的目的,并将其用于复合维生素B药片的分析,取得了满意的结果.     

On the theory underlying the Car-Parrinello method and the role of the fictitious mass parameter

The theory underlying the Car-Parrinello extended-Lagrangian approach to ab initio molecular dynamics (CPMD) is reviewed and reexamined using "heavy" ice as a test system. It is emphasized that the adiabatic decoupling in CPMD is not a decoupling of electronic orbitals from the ions but only a decoupling of a subset of the orbital vibrational modes from the rest of the necessarily coupled system of orbitals and ions. Recent work [J. Chem. Phys. 116, 14 (2002)] has pointed out that, due to the orbital-ion coupling that remains once adiabatic decoupling has been achieved, a large value of the fictitious mass mu can lead to systematic errors in the computed forces in CPMD. These errors are further investigated in the present work with a focus on those parts of these errors that are not corrected simply by rescaling the masses of the ions. It is suggested that any comparison of the efficiencies of Born-Oppenheimer molecular dynamics (BOMD) and CPMD should be performed at a similar level of accuracy. If accuracy is judged according to the average magnitude of the systematic errors in the computed forces, the efficiency of BOMD compares more favorably to that of CPMD than previous comparisons have suggested.     

From the Micro- to the Macro-: Managing the Conservation of the Warship,Vasa

Sweden's famous warship, Vasa, sank on her maiden voyage in August 1628, and remained on the bottom of Stockholm harbour for 333 years. Raised in 1961, she became the first large-scale wooden object to be treated with polyethylene glycol (PEG). In the summer of 2000 a number of acidic salt precipitations were noticed on the surface of the ship and on wooden artefacts in the storerooms. An international research project has been established to look into the causes of this problem and suggest possible re-treatments. Meanwhile projects are underway to monitor movements in the ship, to build a better support system, and to replace the thousands of iron bolts holding the structure together, while a sophisticated new climate system has recently been installed in the museum.