高纯度玉米黄素的制备

本文研究了氢氧化钾(KOH)与叶黄素的摩尔比例、KOH水溶液的摩尔浓度、反应温度、料液比四个因素对叶黄素转化为玉米黄素反应的影响。实验结果表明,当KOH和叶黄素的摩尔比为56:1,KOH水溶液摩尔浓度为12M,料液比为1:25,温度为90℃,反应时间为1h,叶黄素转化效率最高,经过重结晶,所得玉米黄素的含量可达90%以上,总收率在60%以上。     

玉米黄素制备工艺中强碱的影响研究

玉米黄素和叶黄素共同构成视黄斑色素,视黄斑色素在保护眼健康方面起到非常重要的作用.本文以叶黄素为原料,在碱性条件下经异构化反应制备玉米黄素,研究了有机碱液的加入方式、有机碱液的加入量对异构化反应的转化率、收率的影响,分析了造成这些影响的可能原因.实验结果表明,叶黄素异构化制备玉米黄素过程中应控制有机碱液的加入量,并以滴...     

叶黄素和玉米黄素抑制口腔上皮细胞癌增殖的实验研究

为阐明玉米蛋白粉类胡萝卜素提取物叶黄素和玉米黄素对人口腔上皮癌细胞株KB凋亡的诱导作用,探讨其分子生物学机制。本文采用单细胞凝胶电泳、DNA凝胶电泳、流式细胞术检测叶黄素和玉米黄素诱导口腔癌细胞凋亡的情况。结果发现:单细胞凝胶电泳显示玉米蛋白粉叶黄素和玉米黄素能造成KB细胞DNA损伤、DNA凝胶电泳显示能使KB细胞DNA发生明显的降解,DNA周期分析主要阻断口腔癌细胞由G1向S期转变;流式细胞仪检测明显抑制人口腔癌细胞株KB中bcl-2基因的蛋白表达,明显升高p53、Bax基因的蛋白表达;说明玉米蛋白粉类胡萝卜素提取物叶黄素和玉米黄素具有明显抑制口腔上皮癌细胞增殖、并诱导其凋亡的作用。     

叶黄素、玉米黄素分子结构修饰对抑制肿瘤细胞增殖活性的影响

目的:探讨叶黄素、玉米黄素的结构与抗肿瘤效果之间的关系。方法:以从玉米蛋白粉中分离、提取的叶黄素和玉米黄素为原料,通过化学合成的方法分别对其所携带的紫罗酮环上的羟基进行单、双乙酰化修饰,所合成的产物用紫外可见光扫描,液质联用,核磁共振等手段分子结构的鉴定;用MTT(噻唑蓝)的方法测定各叶黄素、玉米黄素结构被修饰前后抑制人口腔上皮细胞癌KB增殖活性的变化。结果:叶黄素、玉米黄素分子紫罗酮环上的羟基被乙酰基取代后,其抑制细胞增殖的活性有所降低。结论:叶黄素和玉米黄素分子结构中羟基取代基的存在对其调节肿瘤细胞的增殖能力有一定的贡献。     

玉米蛋白粉中叶黄素和玉米黄素对口腔癌细胞DNA的损伤作用

研究玉米蛋白粉中叶黄素和玉米黄素对人口腔癌KB细胞的作用机制。在人口腔癌KB细胞的细胞培养液中分别加入40μL/L、60μL/L叶黄素和30μL/L、40μL/L玉米黄素,分别培养48h、72h。用单细胞凝胶电泳(SCGE)检测叶黄素和玉米黄素对人口腔癌KB细胞DNA损伤程度。玉米蛋白粉中叶黄素和玉米黄素可引起KB细胞DNA链断裂,细胞尾长、尾DNA百分含量和尾矩显著高于对照组,差异有统计学意义(P<0.01)。叶黄素和玉米黄素能导致人口腔癌细胞KB的DNA损伤,抑制肿瘤细胞生长。     

应用C30-HPLC-PDA分离与鉴定食品中全反式叶黄素和玉米黄素

在装备了二极管阵列检测器(PDA)的高压液相色谱(HPLC)上,应用C30柱,食品中的全反式叶黄素和玉米黄素获得了良好的分离。分离的色谱条件为:WatersYMCCarotenoidS-5(4.6×250mm)柱;乙腈-甲醇-三乙胺(75:25:0.05)为流动相A,甲基叔丁基醚-三乙胺(100:0.05,)为流动相B,流动相B在20min内由0%线性增至55%;流速为1.0ml/min;PDA波长范围为260～700nm;进样量为20μl。根据其色谱行为和光谱特征,全反式叶黄素和玉米黄素可被定性。这一结果使二者在C30-HPLC-PDA上的定量成为可能。     

玉米蛋白粉中叶黄素和玉米黄素对小鼠巨噬细胞免疫调节活性的研究

采用体外细胞培养方法,研究小鼠腹腔巨噬细胞在LPS刺激的情况下,从玉米蛋白粉中提取的叶黄素和玉米黄素对其生成NO的影响作用.噻唑蓝（MTT）法检测淋巴细胞及巨噬细胞增殖,比色分析检测巨噬细胞吞噬中性红的能力,生物法测定肿瘤坏死因子α（TNF-α）活性,Griess法测定NO含量.结果表明：叶黄素和玉米黄素对小鼠腹腔巨噬细胞的生长有一定的促进作用,当叶黄素、玉米黄素分别为5μmol/L和2.5μmol/L时对小鼠腹腔巨噬细胞产生NO表现为抑制作用,而当叶黄素的浓度在10～40μmol/L、玉米黄素的浓度在5～30μmol/L时巨噬细胞NO的生成水平表现为能显著提高正常小鼠腹腔巨噬细胞产生NO,且呈现剂量效应关系.叶黄素在20～50μ mol/L,玉米黄素在10～40 μ mol/L的浓度范围内,能够促进巨噬细胞吞噬中性红的能力,并能诱导其分泌TNF-α.     

富有保健功效的叶黄素和玉米黄素

<正> 近年来,富有保健功效的叶黄素和玉米黄素越来越成为国内外科学家们研究的热点。近日,由中国营养学会营养与保健食品分会举办的"叶黄素和玉米黄素来源与功能作用专家论坛"在京举行。会议邀请了来自国内外的专家就国内外对叶黄素、玉米黄素研究的最新进展情况,同各方专业与会者进行了交流。叶黄素与玉米黄素都属于类胡萝卜素,具有很强的抗氧化作用。叶黄素与玉米黄素是构成玉米、蔬菜、水果、花卉等植物     

北京社区居民夏秋季节膳食叶黄素、玉米黄素摄入量分析

目的:测算北京社区居民夏秋季膳食叶黄素、玉米黄素摄入量。方法:采用高效液相色谱法(HPLC)对13种常见蔬菜、水果和蛋类中叶黄素、玉米黄素和β-胡萝卜素含量进行检测。运用定量食物频率表结合HPLC测定结果,计算居民膳食叶黄素、玉米黄素摄入量。结果:被调查的541名45岁以上社区居民中,叶黄素、玉米黄素平均摄入量分别为10201.4±12852.6μg/d和245.0±260.0μg/d。二者的摄入量在月人均收入1000～1999元者中最低。39.1%和30.2%的膳食叶黄素来源于菠菜和韭菜,40.6%和31.9%的膳食玉米黄素来自韭菜和鸡蛋。结论:利用定量食物频率表结合对常见食物的HPLC测定结果,估计了北京社区居民膳食叶黄素、玉米黄素的膳食摄入量。收入水平是影响居民二者摄入量的因素之一。菠菜、韭菜为被调查者膳食叶黄素的主要来源,韭菜、鸡蛋为其膳食玉米黄素最重要的来源。     

高纯度番茄红素的制备

从番茄红素油树脂出发,经过皂化、硅胶柱层析和重结晶处理,获得高纯度的番茄红素,产品纯度达92.8%,能满足工业对高纯度番茄红素的要求.     

高效液相色谱法测定奶粉中玉米黄质含量

目的 本文建立了一种使用高效液相色谱快速检测奶粉中玉米黄质含量的方法。方法 奶粉样品用蛋白酶在45℃条件下振荡酶解30 min,正己烷/丙酮(9：1)重复提取2次,旋转蒸发浓缩至近干,正己烷/乙酸乙酯(65：35)复溶后,用Si 60(100 mm×2.1 mm,5 μm)色谱柱经高效液相色谱紫外检测器测定,外标法定量测得。结果 试验结果表明,玉米黄质在14.018 min附近出峰,玉米黄质浓度在0 μg/mL-4.0 μg/mL范围内呈良好线性关系(R_²=0.99982)。空白奶粉样品中添加玉米黄质含量为63.35 μg/100 g,126.7 μg/100 g,316.75 μg/100 g时,加标回收率在95.8%～96.7%之间,相对标准偏差在1.1%-3.9%之间。当取样量为2 g,定容体积为5 mL时,检测限为20 μg/100 g,定量限为50 μg/100 g。结论 该检测方法相对于其他前处理较简单,具有较高准确度、灵敏度、稳定性,可以满足奶粉中玉米黄质含量的检测。     

高效液相色谱法同时测定护眼保健品中叶黄素和玉米黄质

目的 建立高效液相色谱法(high performance liquid chromatography, HPLC)同时测定护眼保健品中叶黄素和玉米黄质的分析方法。方法 样品用胰酶氯化钠预处理后, 经无水乙醇及石油醚提取, 在55 ℃水浴中用40%氢氧化钾-甲醇溶液皂化30 min, 无水乙醇稀释后, 选用色谱柱YMC Carotenoid S-5 (250 mm× 4.6 mm, 5 μm), 以甲醇:三氯甲烷(4:1, V:V)为流动相, 流速为1.5 mL/min, 柱温为25 ℃, 于445 nm波长处测定样品。结果 叶黄素在0.3906~12.4979 μg/mL范围内线性关系良好, 相关系数r2为0.9999, 平均回收率为91.5%~95.2% (n=9), 检出限为0.0075 μg/g; 玉米黄质在0.1474~4.7184 μg/mL范围内线性关系良好, 相关系数r2为1, 平均回收率在98.6%~110.2% (n=9), 检出限为0.0120 μg/g。结论 该方法快速、稳定, 能够适用于护眼保健品中叶黄素和玉米黄质的同时测定。     

多重包埋技术在微囊化玉米黄质中的应用

玉米黄质是一种非常重要的类胡萝卜素,具有独特的共轭双键,这一结构决定了它不稳定性,在光、热氧的作用下极易被氧化降解.为此采用多重包埋技术对玉米黄质进行微囊化,并通过单因素和正交实验研究确定了最佳壁材组合.大大提高了玉米黄质的水溶性、稳定性和生物利用度.     

以菊芋为主要营养基质的高活力乳酸菌发酵剂制备

研究了在以菊芋为营养基质的培养基中添加营养因子对植物乳杆菌生长和发酵活力的影响。试验结果表明,菊芋可以作为乳酸菌培养的良好基质,葡萄糖、蛋白胨等营养成分的添加可以提高乳酸菌的增殖效果,在10%菊芋浸汁中添加2.5%的葡萄糖、4%植物蛋白胨及0.05%的Mn SO4,经34℃发酵20 h后,乳酸菌最大菌浓可达3.5×109CFU/m L左右,且菌体具备较高的发酵活力,当其应用于菊芋泡菜低温发酵时,发酵8 d后泡菜体系的p H值下降至3.6左右,发酵液中的活菌数可达2.0×107CFU/m L以上。Mn2+是乳酸菌体保持高发酵活力的重要因子,在培养基中缺乏Mn2+的情况下,发酵液中乳酸菌液活菌数并不会有显著的下降,但当其应用于菊芋泡菜发酵时,发酵后泡菜体系的p H值保持在4.0左右,发酵液中的活菌数也仅有1.2×107CFU/m L左右,说明Mn2+的存在对于乳酸菌的发酵活力至关重要。     

Biotechnological production of zeaxanthin by microorganisms

BackgroundZeaxanthin is a natural xanthophyll carotenoid that is widely produced by plants, algae and microorganisms and plays a critical role in the prevention of age-related eye diseases, such as macular degeneration and cataracts. Zeaxanthin is also used in the food, pharmaceutical and nutraceutical industries because of its strong antioxidant and anti-cancer properties. To date, zeaxanthin has been primarily produced by extraction from natural resources, especially plants, which is costly and environmentally unfriendly. The biosynthesis of zeaxanthin by microorganisms has been reported in lots of works to provide another potential route for zeaxanthin production.Scope and approachIn this review, we discuss the zeaxanthin biosynthetic pathway, naturally occurring zeaxanthin-accumulating microorganisms containing bacteria and microalgae, the optimization of fermentation conditions using these microorganisms, and zeaxanthin production using microbial cells factory constructed by metabolic engineering. The different metabolic engineering strategies and the zeaxanthin-accumulating level of the reviewed wild and engineered microorganisms are also considered. Furthermore, this work presents perspectives concerning the microbial production of zeaxanthin, especially the trends to construct the metabolically engineered microorganisms for zeaxanthin production.Key findings and conclusionsTo date, all the reported wild zeaxanthin-accumulating microorganisms belong to either bacteria or microalgae, while most of the reported engineering microorganisms for zeaxanthin production are Escherichia coli or yeast. A feasible strategy for zeaxanthin production is the use of metabolic engineering to construct a zeaxanthin-accumulating microbial cells factories followed by the optimization of fermentation with the engineered strain. Besides the simple overexpression of the biosynthesizing genes, the dynamic regulation of the constructed pathway has also been used for zeaxanthin production by metabolic engineering. Construction of better microbial cells factories which produce more zeaxanthin will profit from the breakthrough of the following fields: Introduction of higher plant zeaxanthin biosynthesizing genes into microorganisms; Characterization of novel zeaxanthin pathway genes from the wild microorganisms producing high level of zeaxanthin; Deep investigation of the farnesyl diphosphate formation pathway; Construction of microbial host with weak antioxidative capacity.     

Screening sweetcorn for enhanced zeaxanthin concentration

BACKGROUND: New varieties of fruits and vegetables, with higher carotenoid levels, are being developed to improve the potential health benefits to consumers. To assist the development of a new variety of high zeaxanthin sweetcorn, an analytical screening method was developed, including chromameter measurement of hue angle and optimized extraction for HPLC, and applied to 385 lines of a breeding population and six commercial varieties. RESULTS: Saponification had no effect on carotenoid extraction. In the breeding population, carotenoid levels had a wide range with the highest levels of zeaxanthin being 11.9 mg kg^?1 fresh weight, which was at least six times greater than the tested commercial varieties. The regression of hue angle versus zeaxanthin was described by the equation, hue angle = 76.16 + 4.50 × exp(?0.24 × zeaxanthin) + 11.73 × exp(?0.24 × zeaxanthin), r² of 0.59. The top 6% of lines, with regards to zeaxanthin (zeaxanthin + β‐cryptoxanthin + β‐carotene) and total carotenoids, all had hue angles ≤84.1°. CONCLUSION: The use of a hue angle of 85° as a maximum cut‐off for liquid extraction will allow for much increased efficiency in screening further germplasm for high zeaxanthin lines. There appears to be significant opportunity to further increase the zeaxanthin concentration by selecting for lines which preferentially channel carotenoid synthesis towards zeaxanthin. Copyright © 2009 Society of Chemical Industry     

热丝CVD法制备大面积高质量自支撑金刚石厚膜

采用热丝CVD方法,在Ф110mm的钼基体上,以丙酮为碳源,在高纯氢的作用下,成功地合成了高质量自支撑金刚石厚膜。X射线、SEM和拉曼光谱分析表明,所合成金刚石厚膜质量均匀,晶体单一、完好、纯度高,生长速度快,已接近制备实用化的金刚石膜的要求。     

一种枸杞中玉米黄素检测的方法

研究的目的是建立一种可行的测定枸杞中玉米黄素含量的方法,其特征是不使用参比样品而结果具有可靠性。在实验中,应用可见光分光法,根据朗伯-比尔定律测定并计算萃取物中总类胡萝卜素含量。然后,用C30-HPLC测定样品中类胡萝卜素酯的相对峰面积。最终,对样品进行完全皂化水解,用C30-HPLC测定皂化物的中玉米黄素组分的相对峰面积。根据样品中总类胡萝卜素含量,采用峰面积归一法计算样品中玉米黄素组分的绝对含量。本方法具有较强的实用性,在不使用参比样品的情况下,能应用于我国食品添加剂和保健食品行业中对玉米黄素的多数检测工作中,并获得可靠的结果。本方法对我国玉米黄素食品添加剂和保健食品行业标准的制定和原料质量评估具有一定的参考价值。     

高效液相色谱法测定枸杞相关食品中枸杞酸和玉米黄质二棕榈酸酯的含量

目的 建立高效液相色谱法分析枸杞原料、提取物和相关配方产品中枸杞酸和玉米黄质二棕榈酸酯的含量。方法 采用Poroshell 120 HILIC柱,以乙腈-磷酸水（90:10, V:V）为流动相进行分离枸杞酸,在紫外检测波长235 nm下进行检测,外标法定量。用Dionex Acclaim C30柱,以甲醇-甲基叔丁基醚为流动相进行梯度分离玉米黄质二棕榈酸酯,在紫外检测波长452 nm下进行检测,外标法定量。结果 枸杞酸的检出限为10 mg/kg,定量限为30 mg/kg;在10～200 mg/L的浓度范围内线性良好,相关系数为0.9999;枸杞原料、提取物和相关配方产品中的加标回收率在84.3%～98.1%之间,相对标准偏差(relative standard deviation, RSD)在1.3%～4.7%之间;精密度的RSD在0.74%～1.2%之间;重复性的RSD分别为1.3%～3.1%之间。玉米黄质二棕榈酸酯的检出限为10 mg/kg,定量限为30 mg/kg;在0.5～10 mg/L的浓度范围内线性良好,相关系数为0.999;枸杞原料、提取物和相关配方产品中的加标回收率在88.6%～98.6%之间,RSD在1.5%～4.5%之间;精密度的RSD在1.2%～2.1%之间;重复性的RSD在2.0%～4.5%之间。结论 本方法操作简便,快速,分离度和准确度高,可用于枸杞原料、提取物和相关配方产品的质量控制。     

Post harvest improvement of zeaxanthin content of vegetables

Zeaxanthin is a carotenoid produced by plants and has been associated with protection of the photosynthetic machinery under light stress and, together with lutein, in protection of the central retina of the eye. Zeaxanthin levels in blood plasma have been negatively correlated to the development of AMD (age-related macular degeneration) (Gale et al., 2003). Under normal conditions, plants have a low content of zeaxanthin. The aim of this study was to increase the zeaxanthin content in green vegetables by post harvest treatments. Efficient conditions for activation of the endogenous enzyme system generating zeaxanthin was established and included incubation at low pH (2.5–5.5), with the membrane permeable acetic acid/acetate buffer at room temperature or above for 30 min or more. Typically more than 20-fold increase in zeaxanthin content was obtained for spinach, corn salad, parsley, basil, lemon balm and peas. For spinach up to 4 mg/100 g fresh weight of leaves were obtained. In consequence less amount of vegetables would be needed in the diet to provide the same amount of zeaxanthin for the eye.