天然维生素E醋酸酯的合成

以天然VE为原料,与醋酸酐进行酯化反应合成天然VE醋酸酯。以转化率为指标,通过单因素实验和正交实验,得出最佳合成条件为:反应时间60 min,反应温度110℃,醋酸酐用量45%,催化剂用量4.0%。在最佳条件下VE醋酸酯转化率达99.4%。     

响应面法优化甘油酯转甲酯化条件

在反应温度、反应时间和甲醇钠用量3个单因素实验基础上,利用响应面分析法,以交酯化后样品中甘油和VE含量为评价指标,对甘油酯转甲酯化最佳条件进行了研究。结果表明,最佳反应温度73.7℃、反应时间2.1 h、甲醇钠用量0.51%(W/W)。在最佳条件下,VE保存率为90.5%,酯化率为89.4%。     

天然维生素E琥珀酸酯的制备

维生素E琥珀酸酯有比维生素E更强的化学稳定性,同时其还有抗癌功效,是水溶性维生素E--TPGS的基本原料.介绍了用天然维生素E酯化制备维生素E琥珀酸酯的方法,选用三乙胺作为催化剂制备维生素E琥珀酸酯.通过实验优化后得到优化的工艺条件为(原料50 g):反应时间为4.0 h、琥珀酸酐用量为原料维生素E的150%(W/W)、催化剂用量为5.0 mL、反应温度为55℃.在优化的工艺条件下,维生素E酯化率为93.91%.     

维生素E脂质体的制备工艺筛选、优化及其性质研究

目的优化维生素E（VE）脂质体的制备工艺并考察其性质。方法采用乙醇注入法、乙醚注入法、逆相蒸发法、薄膜水化法和复乳法分别制备v。脂质体,以包封率和保留率为考察指标,选择最优制备方法;经L9（3^4）正交试验设计优化选择,确定脂质体的最佳配方。结果薄膜水化法制备所得的VE脂质体包封率最高,VE保留率较高;用薄膜水化法制备脂质体的最佳配方为磷脂：VE：胆固醇=20：0．8：1．5;用透射电镜观察最佳实验组VE脂质体发现其具有指纹状结构,Zeta电位为．30．9±0．9mV,平均粒径为33．7nm。结论薄膜水化法制得的V。脂质体具有包封率高,VE保留率高,粒径均匀等特点。     

黑莓天然维生素E纯化技术研究

目的建立一种硅胶柱层析纯化黑莓种籽油中天然VE的方法。方法采用单因素实验的方法,以维生素E的含量为考察指标,对洗脱剂种类、洗脱剂配比、硅胶用量、洗脱剂用量进行优化。结果黑莓天然VE的最优纯化工艺参数为:硅胶与维生素E粗提物的质量比3?1;乙醇?正己烷(8?1,V/V)为洗脱剂,洗脱剂用量为粗提物的15倍。在此条件下,纯化物中维生素E的含量可以达到(51.5±0.530)%。结论采用硅胶柱层析方法可以有效纯化黑莓天然维生素E。     

维生素E油酸酯的合成研究

本文通过油酸酰氯强活性中间体合成了维生素E油酸酯。对影响维生素E油酸酯产率的因素-原料配比、溶媒用量、反应温度和反应时间等四个因素进行了分析，采用L16（4^5）正交设计进行优化，并采用TLC和HPLC法对产品进行了分析。最佳合成工艺为：油酸酰氯与维生素E的摩尔配比为3：1，催化剂吡啶用量为0．025ml，反应时间4h，温度45℃，反应转化率为41．8％。     

维生素E乙酸酯制备方法与光谱表征

利用新型催化剂固体超强酸SO42-/TiO2合成VE乙酸酯,研究催化剂用量、反应物配比、反应时间、反应温度等因素对合成的影响,通过模糊数学模型确定了最佳合成条件。最优合成工艺:温度40℃,时间3h,乙酸酐与VE摩尔比1.2,固体超强酸SO42-/TiO2催化剂用量1.0g,反应酯化率为96.6%。利用IR、元素分析和1H NMR对产物结构进行表征,证明得到的产物为VE乙酸酯。     

生育酚琥珀酸酯合成的研究

实验采用丙酮作溶剂、三乙胺为催化剂,VE与琥珀酸酐酯化合成VE琥珀酸酯。通过正交试验考察了反应过程中琥珀酸酐与VE的配比(A)、溶剂用量(B)、催化剂用量(C)和反应温度(D)4个因素对VE转化率的影响。结果表明,因素影响的主次顺序为A>B>C>D,优化工艺条件的转化率为59.62%,经单因素进一步优化后转化率有很大的提高。     

维生素E对花椒油过氧化值的影响

在花椒油中添加维生素E(VE),考查了紫外光、温度、氧化剂对花椒油过氧化值(POV)的影响.结果表明:添加VE能够减缓花椒油的氧化速度.分别用紫外光照射和0.06 mol/L KClO3氧化240 min,不加VE花椒油的过氧化值比加VE的油高18.28%和43.64%;100℃温度下受热240 min,不加VE花椒油的过氧化值是加VE油的6.58倍;用0.6%H2O2氧化 240 min,不加VE花椒油的△POV/(POV)0值比加VE的油大28.75%.     

青藏地区青稞中VE 的高效液相色谱测定

采用高效液相色谱法对青藏高原的16 种不同地区和品种的青稞中δ-VE、γ- VE 和α- VE 同时进行了含量的测定,为青稞的质量评价和综合利用提供依据。采用Symmetry C18(4.6mm × 250mm,5μm)色谱柱;甲醇:水=98:2(V/V)为流动相;检测波长295nm;柱温25℃;流速1ml/min。结果表明,青藏地区的青稞中VE 总含量在0.3～0.8mg/100g,其中青海地区青稞中VE 的平均总含量比西藏地区低约10%。     

高效液相色谱法测定食品中维生素E的研究进展

该文综述了维生素E的发现、研究发展、医疗保健功效以及各种食品中维生素E的高压液相色谱分析方法等。     

脂溶性维生素对多种慢性疾病治疗作用的研究进展

综述脂溶性维生素抗炎、抗氧化等生物活性对糖尿病、骨质疏松、慢性肾脏病等慢性疾病治疗作用的研究进展。     

Determination of vitamins A and E in cooked sausages

A reliable and sensitive reverse-phase HPLC method is described for the separation and quantification of all-trans-retinol and dl-α-tocopherol in cooked sausages. Samples were chromatographed with UV and fluorescence detection on a 15 cm × 0.4 cm i.d. Spherisorb ODS-2, 5 μm column, using as mobile phase a mixture of 90% acetonitrile and 10% tetrahydrofuran. Sample preparation included saponification and extraction by n-hexane. Addition of pyrogallol and oxygen-free conditions avoided oxidation of both vitamins, increasing recovery percentages, which ranged from 90.0 to 95.0%. Precision was 1.0% (within a day) and 3.4% (between days) for all-trans-retinol and 1.1% (within a day) and 2.6% (between days) for dl-α-tocopherol. Detection limits were 10 μg/100 g for all-trans-retinol and 0.1 mg/100 g for dl-α-tocopherol with a signal-to-noise ratio of 3. Twenty samples of six different products were analyzed in duplicate. Average for all-trans-retinol in “enriched chopped” was 108 mg/100 g fresh weight, and the mean value for dl-α-tocopherol in “enriched chopped” was 2.3 mg/100 g fresh weight.     

高效液相色谱法同时测定食用油中维生素A和E的方法

本文建立了高效液相色谱法同时测定食用油中维生素A和4种维生素E生育酚的方法。利用维生素A醋酸酯和维生素E生育酚分别在325nm和294nm的波长下的吸收特性。以液相色谱紫外检测器双波长的方式,考察研究处理方式并开发同时检测食用油中维生素A和E的方法。通过该方法结果表明：维生素A的精密度RSD为0.84%~1.39%,回收率范围在95.8%~104.4%;维生素E的各生育酚组分精密度RSD为2.01%~4.14%,回收率范围在96.2%~112%。本方法也可应用于测定不同食用油中维生素A和E且有效可靠。测得葵花籽油维生素A含量735.58±3.86 μg/100g,维生素E(α-TE)的含量为54.33±2.92 mg/100g;玉米油维生素A含量676.75±2.15 μg/100g,维生素E(α-TE)的含量为24.78±1.36 mg/100g。通过方法验证,确认液相色谱同时检测维生素A和E的方法用于食用油中有效可靠。     

不同贮存条件下生菜中维生素C和E含量分析

采用高效液相色谱法对在5个时间梯度处理、2个温度梯度处理条件下生菜叶片中维生素C和E含量进行了分析。结果表明,维生素C对贮存时间和温度特别敏感。低温或室温贮存1d的生菜中维生素C含量均损失50%以上,而维生素E含量包括α-生育酚含量反而有所提高;但低温或室温贮存3d后生菜中维生素C含量和维生素E含量特别是α-生育酚含量均急剧下降。因此,从营养利用的角度考虑,生菜的贮存以低温1～3d为宜,室温和长时间贮存会造成维生素C和E的大量损失。     

分光光度法测定天然维生素E总含量

对VE含量测定的快速方法———分光光度法进行了比较详细的探讨。确定了测定时的最大吸收波长在510nm处,显色反应产物吸光值在0～0.8范围内与样品中VE浓度呈线性相关,标准曲线y=0.0096x-0.0047,相关系数为0.9984,方法平均回收率为97.02%,变异系数为1.34%,最小检测浓度为1.2280×10-6mol/L。分光光度法与HPLC法测定结果相比较,最大相对偏差不高于5%。     

提高维生素E抗油脂氧化效果的研究

维生素E对油脂的抗氧化效果是肯定无疑的。然而它的效果与它的同分异构体的含量、添加量以及实验油脂的种类、储存温度等条件密切相关。虽然VE 比合成抗氧化剂的抗氧化效果差些 ,但VE 是天然抗氧化剂 ,添加在食用油或油脂食品中 ,可解除人们的不安心理。为了在实践中更有效地使用VE,对使用柠檬酸或L -抗坏血酸 (VC)作为增效剂提高VE 抗氧化效果进行了研究。研究结果表明 ,以柠檬酸作为增效剂 ,添加于猪油中 ,6 0℃烘箱试验 ,VE 的抗氧化性提高了 ,比单独使用VE 效果好 ;以柠檬酸或VC 作增效剂添加于机榨菜籽油中 ,室温储存 ,VE 的抗氧化效果明显提高。两者均比单独使用VE 抗氧化效果好 ;以柠檬酸或VC 作增效剂添加于精炼棉籽油中 ,室温储存 ,对于提高VE 抗氧化效果不明显     

Dietary antioxidants in the prevention of hepatocarcinogenesis: A review

In this review, the role of dietary antioxidants in the prevention of hepatocarcinogenesis is examined. Both human and animal models are discussed. Vitamin C, vitamin E, and selenium are antioxidants that are essential in the human diet. A number of non‐essential chemicals also contain antioxidant activity and are consumed in the human diet, mainly as plants or as supplements, including β‐carotene, ellagic acid, curcumin, lycopene, coenzyme Q₁₀, epigallocatechin gallate, N‐acetyl cysteine, and resveratrol. Although some human and animal studies show protection against carcinogenesis with the consumption of higher amounts of antioxidants, many studies show no effect or an enhancement of carcinogenesis. Because of the conflicting results from these studies, it is difficult to make dietary recommendations as to whether consuming higher amounts of specific antioxidants will decrease the risk of developing hepatocellular carcinoma.     

Changes in content of vitamins A and E in growing‐up milk throughout its shelf life

The stabilities of vitamins A and E were determined in 51 samples of growing‐up milk stored at 23, 30 and 37 °C for up to 9 months. Initially, the content of vitamin A and vitamin E was 330 RE μg/100 mL and 1.78 α‐TE mg/100 mL, respectively. Decreases in vitamin content were higher (P < 0.05) in formulas stored at 37 °C (from 330 to 111 μg RE/100 mL for vitamin A and from 1.78 to 1.16 mg α‐TE/100 mL for vitamin E). Over‐fortification of growing‐up milk could be recommended for vitamin E.     

Aflatoxin–albumin adducts and correlation with decreased serum levels of vitamins A and E in an adult Ghanaian population

A study of aflatoxin (AF) exposure and the levels of vitamins A and E was carried out with a group of 507 Ghanaian participants. AFB₁–albumin adducts (AFB-AA) were measured by radioimmunoassay and vitamins A and E were measured by high-performance liquid chromatography (HPLC). The average level of serum AFB-AA was 0.94 ± 0.64 (range = 0.1–4.44) pmol mg^?1 albumin. Mean levels of vitamins A and E were 1.32 ± 0.48 (range = 0.41–4.85) µmol l^?1 and 15.68 ± 4.12 (range = 6.35–30.40) µmol l^?1, respectively. A significantly negative correlation was found between serum AFB-AA and vitamin A levels (r = ?0.110, p = 0.013). An even stronger, significant negative, correlation was found between serum AFB-AA and vitamin E levels (r = ?0.149, p < 0.001). Serum AFB-AA levels were statistically higher (median = 0.985 pmol mg^?1 albumin) in subjects who had low levels of both vitamins A and E as compared with the levels (median = 0.741 pmol mg^?1 albumin) subjects who had high vitamins A and E levels (p _trend = 0.001). To verify these findings, blood samples were again collected from 165 of the 507 people 3 months after the initial collection. Significantly negative correlations were confirmed between levels of serum AFB-AA and both vitamins A (r = ?0.232, p = 0.003) and E (r = ?0.178, p = 0.023). Again, high serum AFB-AA concentrations (median = 1.578 pmol mg^?1 albumin) were found in subjects with low levels of vitamins A and E compared with the concentrations (median = 1.381 pmol mg^?1 albumin) in subjects with high levels of vitamins A and E (p _trend = 0.002). These data show that AF exposure was associated with decreased levels of serum vitamins A and E in high-risk human populations, which may significantly influence the incidence of AF-related adverse health effects.