HPLC测定青稞中的维生素E

建立了青稞中维生素E含量测定的HPLC方法,为青稞的质量评价和综合利用提供依据.采用Symmetry C18(5μm,4.6mm×250mm)色谱柱;V(甲醇):V(水)=98:2为流动相;检测波长295nm;流速1 mL/min.结果表明,青海地区的青稞维生素E总含量在0.3～0.8 mg/100 g.     

维生素E电化学氧化的研究

维生素E又名生育酚,有α、β、γ及δ四种。本文所指的维生素E是α-生育酚即为2,5,7,8-tetramethyl-2-(4',8',12'-trimethyl-tridecyl)-δ-chromanol。其结构式为(图A)及其对映体。它对人体有抗不育症的重要的生物活性,对维生素E的电化氧化机理进行探讨,将有助于揭示它在人体内的氧化化学特性。Kolthoff等人曾研究了维生素E在滴汞电极上的电化学行为。Parker报导了维生素E模型化合物(图B)的阳极氧化,并提出其反应机理。但关于维生素E的阳极氧化机理至今未见报导。本文对维生素E在乙腈、乙醇等不同溶剂中的阳极氧化进行了研究,探讨其氧化     

镁离子、维生素E抗氧化作用的研究

为研究镁离子、维生素E体内外抗氧作用,探讨镁离子抗氧化作用的机制,将3月龄昆明种小鼠70只随机分7组,设正常对照组、氧化对照组、63、42、21mmol／L镁保护组,镁和维生素E保护组,维生素E保护组,饲养10d,腹腔注射0．15％CCl4致小鼠肝损伤,观察镁离子、维生素E对小鼠肝匀浆中MDA、SOD、GSH含量的影响;在肝匀浆中加入FeSO4和H2O2诱导自由基的生成,观察镁离子、维生素E的抗氧化作用。结果表明,镁离子、维生素E能显著降低肝匀浆中脂质过氧化物MDA的含量,对SOD、GSH无明显影响。提示镁离子、维生素E能抑制自由基的生成,促进自由基清除作用。     

高效液相色谱法测定鸡胚蛋食品中的维生素E

鸡胚蛋是在一定温度下经一定时间孵化的鸡蛋,是一种流传于民间的高效药用食品,其维生素E的含量较高。关于维生素E的测定国内外已有报道。有的测定药物制剂中的维生素E,有的测定血液中的维生素E,G. T. Vatassery还对四种维E的异构体进行了分离。本文采用非水反相高效液相色谱法测定了鸡胚蛋罐头食品原料中的维生素E,方法灵敏、简便、快速、重现性好。     

食物中维生素E的快速荧光测定

本文用正交试验方法探讨了粮食、食品、饲料、蔬菜及水果等食物中维生素E荧光测定过程中的各种条件,用0.1M盐酸-乙醇混合溶液代替常规的有机溶剂如乙醚或石油醚(30～60℃)进行样品处理,用石油醚(30～60℃)代替已烷作萃取剂,在λ_(ex)295nm/λ_(em)340nm处测定维生素E,经多次试验,结果令人满意。测定维生素E的相对偏差为2.0～5.0%,维生素E的平均回收率为99.2%。     

生物抗氧化剂的研究——Ⅲ.维生素E在十二烷基硫酸钠胶束中对亚油酸自动氧化的促氧化作用

本文研究了维生素E(α-生育酚)在含有过氧化亚油酸的亚油酸中的反应,发现在乙醇溶液中没有明显的反应发生,但在十二烷基硫酸钠胶束中,维生素E迅速与过氧化亚油酸反应并引发亚油酸的过氧化,吸收氧气,用紫外光谱、高效液相色谱、顺磁共振技术对反应的动力学进行了仔细的研究,证明反应的中间体是α-生育酚自由基,反应的主要产物是α-生育醌,反应机理为α-生育酚及α-生育酚自由基与过氧化亚油酸发生两步连续双分子反应,速率常数分别为2.93和6.21mol/L~(-1)·S~(-1),讨论了反应的胶束效应。     

高效液相色谱测定烟草制品中的维生素E

建立一种超声辅助萃取高效液相色谱测定烟草制品中维生素E的方法.样品用饱和抗坏血酸乙醇溶液萃取,采用ZORBAX Extend-C18色谱柱(150 mm×4.6 mm,5 μm)及FLD检测器在激发波长为298 nm、发射波长为325 nm下检测,流动相为100%甲醇,采用外标法定量.线性相关系数为0.999 96,信噪比为3时检出限为0.12 μg/mL,回收率为96.4%,相对标准偏差为0.7%(n=6).研究表明,烤烟型烟草中维生素E含量远高于晒烟、白肋烟及香料烟;烤烟型卷烟烟丝比混合型卷烟烟丝中维生素E含量高;烟草制品中梗丝和烟草薄片的维生素E含量较低.     

高硒情况下维生素E对幼龄大鼠抗氧化作用的研究

研究了高Se或高维生系E下,幼龄大鼠体内抗氧化活性的变化以及高Se下,维生素E对其体内抗氧化水平的影响。将三月龄Wistar大鼠32只随机分成4组：正常饲料组、高Se高维生素E饲料组、高Se饲料组和高维生素E饲料组。饲至十周末,处死大鼠,按试剂盒要求分别取其血液、心、肝、肾制成标本测SOD、CAT活性及MDA、GSH含量。结果表明,高Se或高维生素E下饲养下的大鼠与对照组比较,血液中SOD活性明显下降;维生素E能明显抑制高Se大鼠血液中SOD活性的下降。结论：单独高Se或高维生素E会降低幼龄大鼠的抗氧化活性,而维生素E能明显提高高Se下幼龄大鼠体内抗氧化活性。     

维生素E的不对称合成

系统地综述了维生素E的合成方法, 旨在为进行维生素E及其相关萜类化合物合成的研究人员提供参考.     

高效液相色谱法测定人血清中维生素A、E、C的含量

分别建立了同时测定人血清中维生素A和维生素E的以及测定维生素C的高效液相色谱方法。维生素A、E血清样品用正己烷提取,ODS色谱柱分离,流动相为甲醇,检测波长为325nm、292nm。维生素C血清样品用维生素C提取溶剂提取,ODS色谱柱分离,流动相为甲醇-30mmol/LKH2PO4缓冲液,检测波长为234nm。维生素A、维生素E、维生素C线性范围分别为89.1～1425.0μg/L、4.6～73.9mg/L、0.5～15.0mg/L,相关系数r均大于0.9996。维生素A、E、C高、中、低3个浓度的平均回收率为84.0%～101.2%,相对标准偏差为0.9%～5.1%。该方法准确可靠,可用于测定人血清样品中的维生素含量。     

Vitamin E

Ohne Zusammenfassung     

Superacid cyclization of (2E,6E,10E,14E)-8-phenylsulfonylgeranylfarnesol tetrahydropyranyl ether

A mixture of (13E,17E)-12-phenylsulfonylbicyclogeranylfarnesol tetrahydropyranyl ether (8) and (13E,17E)-12-phenylsulfonylbicyclogeranylfarnesol (9) was formed by superacid low-temperature cyclization of exclusively trans-8-phenylsulfonylgeranylfarnesol tetrahydropyranyl ether (1). The structures of 8 and 9 were established using spectral data. The optically active form of 9 was also confirmed by retrosynthesis from (+)-sclareolide (10). __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 224–228, May–June, 2007.     

Quantitative determination of prostaglandins E1, E2 and E3 in frog tissue

A method was developed for quantitative determination of endogenous production of prostaglandin (PG)E1, PGE2 and PGE3 by Rana temporaria lung, heart and urinary bladder homogenates, since these tissues contain the precursors, 8,11,14-eicosatrienoic, arachidonic and 5,8,11,14,17-eicosapentaenoic acids. Following homogenization and shaking at 22 degrees C for 30 min, media were extracted by XAD-2, treated with sodium hydroxide in order to convert PGE compounds into PGB compounds, purified by thin-layer chromatography, and analyzed by high-performance liquid chromatography with homo-PGE1 as an internal standard. The ratio of prostaglandins E1, E2 and E3 compared to the ratio of fatty acid precursors in tissue suggested that the tissue content of precursor is not the only factor determining the type of prostaglandin synthesized.     

Stereochemistry of nitrogen E lone pair in NH3E,NOFE, N2O3E2, AgNO2E,and NCl3E

We revisit nitrogen based simple fundamental molecules in their solid state structures, with the purpose of casting new light on the stereoactivity of valence lone pairs (LPs)—formally N(2s²)—in different crystal geometries. Based on coupled investigations of crystal chemistry and ab initio DFT calculations providing the electron localization function (ELF), LP behavior is analyzed precisely by finding its position E, orientation and “volume of influence” which consists in an electronic cloud generated around the so-called ‘centroïd’ Ec of the electronic doublet. The results show the paramount importance of the role of N(2s²) LP in the crystal network architecture through the different case studies pertaining to ammonia (NH₃), nitrosyl fluoride (NOF), nitrosyl nitrite (N₂O₃), silver nitrite (AgNO₂), and nitrogen trichloride (NCl₃). An unexpected direct ionic interaction between [NO]⁺ or Ag⁺ and the centroïd Ec of the [NO₂Ec]⁻ nitrite group has been evidenced in N₂O₃E₂ and AgNO₂, respectively.     

Total Synthesis of Amphidinolide E and Amphidinolide E Stereoisomers

Four amphidinolide E stereoisomers, amphidinolide E (1), 2-epi-amphidinolide E (2), 19-epi-amphidinolide E (3), and 2-epi-19-epi-amphidinolide E (4), have been synthesized via the judicious union of aldehyde 5, allylsilanes 7 or 8, acids 9 or 10, and vinylstannane 6. The C19 stereocenters of the C19 epimeric allylsilanes 7 and 8 were introduced via crotylboration reactions early in the synthesis. [3+2] Annulation reactions of aldehyde 5 with allylsilanes 7 and 8 were employed to set the core tetrahydrofuran units of 1-4. Finally, the C2 stereocenter was installed by esterification using acid 9, without incident, or with acid 10, in which case an unexpected and completely stereoselective inversion of C2 occurs.     

HPV E6, E6AP and cervical cancer

Abstract

Every year, approximately 470,000 new cases of cervical cancer are diagnosed and approximately 230,000 women worldwide die of the disease, with the majority (~80%) of these cases and deaths occurring in developing countries. Human papillomaviruses (HPVs) are the etiological agents in nearly all cases (99.7%) of cervical cancer, and the HPV E6 protein is one of two viral oncoproteins that is expressed in virtually all HPV-positive cancers. E6 hijacks a cellular ubiquitin ligase, E6AP, resulting in the ubiquitylation and degradation of the p53 tumor suppressor, as well as several other cellular proteins. While the recent introduction of prophylactic vaccines against specific HPV types offers great promise for prevention of cervical cancer, there remains a need for therapeutics. Biochemical characterization of E6 and E6AP has suggested approaches for interfering with the activities of these proteins that could be useful for this purpose.

Publication history

Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).