维生素E的催化合成路线分析

维生素E具有多种特异的生理活性,同时也是一种优良的抗氧化剂,已经逐渐成为维生素领域中的焦点,市场需求不断增加。目前合成维生素E占据市场的80%以上,提升维生素E的产量和生产效率势在必行。天然维生素E包括四种生育酚类物质和四种生育三烯酚类物质,其中α-生育酚含量最大,生理活性也最高。本综述简要介绍α-生育酚的合成路线,其中包括2, 3, 5-三甲基氢醌和异植物醇的合成以及它们二者缩合的反应。本文着重阐述路线的设计和催化剂的选择,并对存在的问题及潜在的解决办法进行评述和展望。     

合成维生素E中间体——三甲基苯醌新工艺

近几年人们对维生素E的需求不断增加。它能增强人体活力、延缓衰老、预防动脉硬化,因而作为重要药物和食品、化妆品的添加剂;它还能增加牲畜家禽的繁殖率和产蛋率而被大量用作牲畜家禽的饲料添加剂。1983年国外维生素E的年产量为8,000吨,我国仅为30吨。产量低的原因之一是合成维生素E的中间体——三甲基苯醌需要进口。为解决这一问题、国家科委和中国科学院将合成三甲基苯醌     

维生素E与铅

维生素E参与血红素或血红素蛋白质的合成 ,并能同时影响ALS和ALAD活性。在实验中观察到 ,维生素E缺乏的大鼠发生铅中毒时 ,可出现贫血、脾大和红细胞脆性增加 ,通过饲料补充维生素E则可预防由铅引起的红细胞变形 (LevanderOA ,1 975 ,1 979)。Dhawan也发出 ,在接触铅的同时 ,补充维生素E可预防血ALAD活性下降、尿中ALA升高及铅在血和肝中的蓄积。维生素E对铅的这种预防作用可能与其抗氧化特性和影响药物代谢酶系有关。Trivedi ( 1 998)最近观察到 ,用维生素E预处理可降低肝、心LPO含量 ,增加肝、肾过氧化氢酶(CAT)活性。维生素…     

离子液体中聚乙二醇维生素E琥珀酸酯的合成

以离子液体为催化剂,由维生素E经两步酯化反应合成了聚乙二醇1000(PEG1000)维生素E琥珀酸酯。以离子液体1-(N',N'-二甲胺乙基)-3-甲基咪唑四氟硼酸盐为催化剂、1,2-二氯乙烷为助溶剂、维生素E与琥珀酸酐摩尔比为1:1.2,在80 ℃条件下反应4 h,维生素E琥珀酸酯(TAS)的产率为90%。以1-丙磺酸基-3-甲基咪唑硫酸氢盐/甲苯为反应体系,TAS与PEG1000摩尔比为1:2,在100 ℃下反应5 h,PEG1000维生素E琥珀酸酯(TPGS)收率为91%。     

与缺铁性贫血有关的维生素及微量元素

主要介绍了维生素及微量元素与缺铁性贫血之间的关系。缺铁性贫血(IDA)是世界范围内普遍存在的营养性疾病，是因人体储存铁缺乏导致血红蛋白合成量减少而形成的一种贫血。许多营养素都与IDA有关，与IDA有关的维生素有核黄素、维生素C、维生素A、维生素E、叶酸及维生素B12，与IDA有关的微量元素有铁、铜、锌、镉、钒、铅等。     

2,3,5-三甲基氢醌制备工艺研究进展

综述了2,3,5-三甲基氢醌的主要合成方法及其生产工艺,并简要分析了该产品工艺开发的新动态.指出2,3,5-三甲基氢醌是合成维生素E的重要中间体,国内来源不足,约60％依赖进口;目前,国内生产工艺严重落后,急需进行工艺改进,以提高产品质量、降低生产成本.     

用高效液相色谱分析工业产品维生素E醋酸酯方法研究

维生素E对人体健康所起的作用,已逐渐为人们所认识。许多国家(包括我国在内),正在研究人工合成维生素E以及从天然物质中提取维生素E的方法,以满足社会对维生素E日益增长的需要。近几年来国外陆续发表了一些分析维生素E的方法,如分光光度法,气相色谱法,以及最近发展起来的液相色谱法。这些方法多是用于分析食品、药品以及动、植物体内多种维生素(包括维生素E)的含量,分析范围较窄,耗时     

聚苯乙烯负载的β-溴乙烯基硒化合物的合成及其在固相合成多取代烯烃中的应用

多取代烯烃的合成一直是有机合成的重要内容之一,在维生素、前列腺素和昆虫信息素等天然产物中都含有（Z）-或（E）-构型的多取代烯基结构单元,元素及金属有机化合物组成的1,2-双官能团化合物在立体选择性地合成多取代烯烃方面的应用研究一直是有机合成的热点。     

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。     

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。     

Simultaneous quantification of vitamins A, D3 and E in fortified infant formulae by liquid chromatography-mass spectrometry

A novel method for the simultaneous quantification of Vitamins A, D3 and E in fortified infant formulae has been developed using isocratic normal-phase liquid chromatography with positive atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS). Food products were saponified and the vitamins were extracted by solid-phase extraction (SPE) on a Chromabond XTR cartridge. Quantification of Vitamins D3 and E were performed with Vitamin D2 and 5,7-dimethyltocol (DMT) as internal standards (IS), respectively while no IS was used for Vitamin A. Detection of the vitamins was made in the selected ion monitoring (SIM) mode. MS calibration curves were linear between 0.15 and 12 mg/l for Vitamin A, 5-400 microg/l for Vitamin D3 and 0.25-20 mg/l for Vitamin E with regression coefficient r2 > 0.996 and the limits of detection were below 1.4 ng. The repeatability (CV) obtained on a reference dietetic infant formula was 2.3% for Vitamin A, 2.6% for Vitamin E and 5.9% for Vitamin D3. The between-day variations (CV) over 6 days were in the ranges of 2.4-6.9% for the three vitamins. The mean recoveries from a reference infant formula spiked with all three vitamins ranged from 96 to 105% with a relative standard error less than 9%. The applicability of the method was demonstrated by analyzing a set of infant formula and infant cereals; similar results were obtained with the LC-MS method and reference HPLC methods.     

Structure Elucidation of a Complex Faldaprevir‐(±)‐α‐Tocopherol Addition Product Reveals Reactivity of Common Excipient Vitamin E‐TPGS

Vitamin E‐TPGS (d ‐α‐tocopheryl polyethylene glycol succinate) is a common excipient used in drug formulations. This excipient is formed by esterification of Vitamin E succinate with polyethylene glycol. As part of an oral formulation for active pharmaceutical ingredient (API) Faldaprevir, Vitamin E‐TPGS was found to decompose under ambient conditions producing free (±)‐α‐Tocopherol which subsequently formed an adduct composed of α‐Tocopherol and the API. The addition product was isolated using liquid chromatography with collections onto solid‐phase extraction cartridges, and full structure elucidation was achieved using mass spectrometry and nuclear magnetic resonance spectroscopy. The results revealed a regioselective addition of α‐Tocopherol to the API that likely occurs through the formation of a stabilized ortho‐quinone methide intermediate. This finding demonstrates the propensity of the common excipient (Vitamin E‐TPGS) to generate chemically active intermediates that may react with formulation ingredients.     

β-环糊精与维生素E包合物的制备及其光谱特性

分别用溶液法、超声波法、微波辐射法制备了β-环糊精与维生素E的包合物,研究了温度、包合时间、β-环糊精与维生素E的摩尔比对包合率的影响,并用荧光光谱法测定了包合物的包合常数Kf为2.84×103 L/mol,用紫外光谱、红外光谱及荧光光谱对包合物进行了表征。     

Vitamin E – a new choice for polyolefin stabilization

Vitamin E based systems provide an alternative way to stabilize polyolefins, instead of the current state-of-the-art stabilizers, for certain niche applications. Its very positive public perception together with its excellent ability for melt flow control at a very low concentration can be utilized to a great extent, particularly for special applications like food and medical packaging. Thus, it's use can lead to an overall reduction in the total amount of additive required compared to a traditional stabilization system in certain applications. Other potential benefits, resulting from the positive attributes of Vitamin E, include low migration, high extraction resistance, very good organoleptics, gel suppression, and longer shelf-life of products. This study examines the performance of Vitamin E based systems in LDPE, LLDPE, HDPE and PP.     

Application of Vitamin E TPGS in ocular therapeutics – Attributes beyond excipient

Diseases affecting the anterior segment and the external surface of the eye are usually treated by drugs applied topically. The formulations designed for this purpose are developed to deliver active pharmaceutical agents to the eye optimally. These formulations are prepared by adding various agents (excipients) that help to maintain stability of the formulation, prevent microbial contamination, and allow easy administration with adequate drug bioavailability with the minimum ocular irritation and toxic effects at the administration site. The excipients do not have their own pharmacological actions, but Vitamin E TPGS (d-α-Tocopheryl polyethylene glycol 1000 succinate) seems to break this notion. Besides having drug formulation enhancement properties, it also possesses antioxidant properties, which have been found to have a beneficial effect on various ophthalmological diseases such as age-related macular degeneration, uveitis, glaucoma, and cataract. In this review, we primarily focus on the properties and applications of Vitamin E TPGS in ocular drug delivery and the benefits of Vitamin E (Vit E) in numerous sight-threatening ailments of the rear and front segment of the eye. Additionally, p-glycoprotein inhibition and the anti-cancer potential of vitamin E TPGS have also been summarized.     

Vitamin E imaging and localization in the neuronal membrane

Vitamin E (alpha-tocopherol) has been implicated in several cellular processes including signaling, transport, lipid membrane curvature, and several neurodegenerative disorders. Vitamin E imaging has been hindered by the inaccessibility of the molecule to traditional immunohistochemical methods. Using time-of-flight secondary ion mass spectrometry (ToF-SIMS), the distribution of major constituents in the cellular membrane of isolated neurons was investigated. There is a significant increase in the vitamin E signal at the soma-neurite junction compared to the cell as a whole (165 +/- 11% of that found across the cell, p = 0.004, n = 12). The observed membrane distribution suggests an important new role for vitamin E in neuronal function.     

Trace element determination in vitamin E using ICP-MS

Vitamin E supplements are either isolated from plants sources or prepared synthetically. Isolation from plants includes eight different tocopherol structures. Vitamin E synthesis includes seven different stereoisomers, which involves the use of several catalysts that may lead to trace element contamination in the vitamin. The use of ICP-MS is an ideal technique for detecting these trace elements. However, the oily nature of the samples requires the development of a sample preparation methodology. This study was done upon the request of synthetic vitamin E manufacturers to test the trace metal purity of their samples. In this work, the comparison of an acid microwave digestion and emulsion preparation is discussed. Cromium, nickel, tin and lead were found in the synthetic vitamin E analyzed and 200, 60, 9 and 45 ppb were the concentrations found respectively for these elements.Digesting the samples gives slightly lower detection limits compared to the emulsion preparation.     

An electrophoretic study of vitamin E status and expression of heat shock proteins in alveolar type II and liver cells

Vitamin E is the most important lipophilic antioxidant. Oxidative injuries are prevented or minimized by vitamin E supplementation. Various physiological and pathological situations are accompanied by vitamin E deficiency. However, it is not clear whether alimentary vitamin E deficiency in itself constitutes oxidant stress that induces appropriate responses, which, in turn, can be avoided by adequate vitamin E supplies, or whether the remaining cellular antioxidants compensate a temporary vitamin E deficiency. We studied effects of the dietary vitamin E status on cellular vitamin E levels and on the expression of heat shock proteins (HSPs) in alveolar type II cells and liver. The expression of HSPs, representing an early and very sensitive marker of cellular stress, was compared with the activity of antioxidative enzymes. Vitamin E depletion caused a substantial increase in HSP32 in alveolar type II cells, whereas in liver there was a marked increase in HSP70. The activity of the antioxidant enzymes, however, did not change significantly. A reversal of HSP expression to almost normal levels was seen after vitamin E resupplementation. These results indicate that, under normal conditions, a suboptimal supply of vitamin E to rats exposes the alveolar type II cells and the liver to reversible cellular stress.