Lutein: a valuable ingredient of fruit and vegetables

Lutein is a human serum carotenoid which is not synthesized by humans and thus must be obtained by the ingestion of food containing it such as fruits and vegetables. Lutein is present in different forms in those foods as all-trans-lutein, cis-lutein, epoxi-lutein, and lutein linked to proteins. It discusses if the intake of lutein or diets supplemented with lutein or diets rich in fruits and vegetables are important in the prevention of diseases like some cancers, cardiovascular diseases, etc., that may be affected by the antioxidant effect of lutein; or in the prevention of age-related macular degeneration and other eye diseases. The concentration of lutein in fruits and vegetables depends on the species. We've included the concentration of lutein in 74 species reported by different authors since 1990. Currently the quantification of lutein is mainly performed by HPLC, but more investigations into a quantification method for lutein, lutein isomers, and epoxi-lutein are necessary. Improvement of lutein extraction methods is important as well. Methods commonly used in the vegetable and fruit industry like heat treatment, storage conditions, etc. can change lutein concentrations; other factors depend on the plant, for instance the variety, the stage of maturity, etc.     

A Simple and Selective Analytical Procedure for the Extraction and Quantification of Lutein from Tomato By-Products by HPLC–DAD

Lutein, a yellow dihydroxylated carotenoid, is present in many dietary supplements due to its biological properties. Currently, lutein is extracted from marigold flowers by expensive and time-consuming processes. Since tomatoes contain significant levels of lutein, in this study we have examined the feasibility of using tomato by-products as an alternative, low-cost source of this carotenoid. The determination of this carotenoid was performed by high-performance liquid chromatography–diode array detection, after selective extraction from tomato waste product samples. Lutein levels ranged from 9.9 to 10.5 μg/g dry weight. Tomato waste products may be indicated as an alternative commercial source of lutein for food fortification and/or dietary supplements.     

Protective effect of lutein after ischemia-reperfusion in the small intestine

Lutein is a carotenoid mainly found in green leafy vegetables and is located in the macula lutea in the human eye. Since humans cannot synthesise lutein de novo, it must be digested as food. The physiological importance of an orally administered compound depends on its interaction with target tissues. There is little information about the effects of intake of lutein in tissues other than the eyes. The aim of this study was to clarify the protective effect of lutein against oxidative injury using ischemia-reperfusion (I/R) model rats and to determine the relationship between pharmacokinetics and antioxidant activity of lutein. Intestinal I/R was induced by 30-min occlusion of the superior mesenteric artery followed by 60-min reperfusion. After 60 min of reperfusion, intestinal tissue was used for analysis of Evans blue dye extravasation, lipid peroxidation and myeloperoxidase activity. Lutein administered before I/R had a significant protective effect against oxidative injury.     

巯基-烯点击化学法合成两亲性叶黄素

叶黄素是一种含氧的类胡萝卜素,适量摄入叶黄素可以减少白内障的发生,叶黄素还可以调节人和动物的免疫能力并且具有预防癌症的作用,但是,叶黄素的低水溶性限制了其在食品和制药行业中的应用。本文研究了利用巯基-烯点击化学法对叶黄素进行亲水性修饰,为叶黄素的化学改性提供了一种新方法。首先以三乙胺为缚酸剂,使叶黄素与丙烯酰氯酯化反应得到两端以乙烯基为端基的中间体,再在紫外光照射下以2,2-二甲氧基-2-苯基苯乙酮为催化剂,使中间体与L-半胱氨酸通过巯基-烯点击化学反应在叶黄素的两端引入亲水性的氨基和羧基,得到两亲性叶黄素。通过UV、IR对产物进行表征,结果表明成功合成了两亲性叶黄素,通过TEM观察两亲性叶黄素在水中自组装形成球形胶束,平均粒径为85nm,有望会大大增加叶黄素在生物体内的吸收率。     

叶黄素研究进展

叶黄素属于类胡萝卜素色素之一,近年研究发现其具有保护视觉,预防动脉硬化,抗氧化,抗癌等作用。该文对叶黄素的性状、来源及提取方法,并对叶黄素功能特性及其在医药、食品、饲料中应用进行综述。     

叶黄素酯在体内消化吸收过程中水解的研究

叶黄素已经证实具有对视网膜黄斑衰退症的防治作用,被认为是一种在食品或药品中有前景的功能因子。叶黄素的制备原料为万寿菊的花,并以叶黄素酯的形式存在。在本研究中,首先从万寿菊干花颗粒中制备叶黄素酯,然后与食用油配制成灌胃液,给SD雄性大鼠一次灌胃,2h后采血,萃取其中的类胡萝卜素,HPLC分析萃取物。分析结果显示:在血清中只能检测到叶黄素单体。这个结果证实:叶黄素酯在消化和吸收过程中被水解成单体,客观上证明了在功能性食品和药品中直接应用叶黄素酯的可能性。     

叶黄素 (lutein)及其护眼功能

类胡萝卜素中有一种叶黄素 ,它广泛存在于绿色蔬菜和人体的血浆和眼球中。它不仅有和类胡萝卜素相似的抗氧化活性 ,而且对视网膜色斑褪化引起的视力下降和失明有明显的保护作用。目前在欧美以叶黄素为功能因子的护眼食品已大量商品化。鉴于从蔬菜中提取不仅含量低成本过于昂贵 ,成熟的技术是从叶黄素含量较高的万寿菊 (金盏花 )中提取。本文简要介绍叶黄素性质功用、不同来源含量以及国内外发展状况。     

叶黄素的提取及应用研究进展

叶黄素属于类胡萝卜素类色素,具有多种生物活性,是当今国际上研究的热点之一。叶黄素的提取技术较多,主要有溶剂抽提法、微波提取法、超临界CO2萃取法、酶介质有机溶剂提取等。近年发现其具有保护视力,预防动脉硬化,抗氧化,抗癌等作用。叶黄素的性状及提取方法,功能特性及其在饲料、食品、药品、保健品等中的应用进行综述。     

万寿菊花中叶黄素酯的提取及皂化工艺

叶黄素具有调节人体的免疫能力、防治老年性视黄斑退化和白内障等作用,目前天然叶黄素的提取原料主要为万寿菊花,万寿菊花的有机溶剂提取物含有大量叶黄素酯,经皂化后可转变为叶黄素,广泛用于食品、食品添加剂、药品及饲料等工业.本文采用甲醇处理万寿菊鲜花后直接用正己烷提取叶黄素酯,并通过L9 (34)正交实验选择了叶黄素酯皂化的最佳条件,即KOH/甲醇浓度为20%,提取液﹕KOH为4 : 1,时间为40min,温度为50℃时,叶黄素酯皂化进行的比较完全.皂化得到的叶黄素在丙酮﹕甲醇(v : v)为1 : 1的混合溶剂中进行重结晶,得到叶黄素晶体,纯度为97.2%.     

Storage stability of lutein during ripening of cheddar cheese

Lutein (3,3'-dihydroxy-alpha-carotene) has been identified as a dietary factor that can delay the onset of age-related macular degeneration (AMD). However, available food sources of lutein contain only modest amounts of the carotenoid. Food fortification with lutein extract has been identified as a low-budget approach to prevent the onset or progression of AMD. The objectives of this study were to 1) incorporate various amounts of lutein into Cheddar cheese; 2) examine the color, pH, microbiological, and sensory characteristics of the Cheddar cheese during storage; and 3) analyze the stability of lutein during the cheese maturation process. Lutein extracted from corn was added to Cheddar cheese in quantities of 1, 3, and 6 mg per serving size. Measurements of the lutein stability were carried out by HPLC using a YMC C30 carotenoid column. Microbiological analyses of cheese samples included aerobic plate count, coliform, and yeast/mold counts. The color attributes a* and b* were significantly different between the treatment and control groups; however, no significant difference was observed in L* value and pH. Significant differences among 1, 3, and 6 mg lutein-enriched cheeses were observed in the aerobic plate count and yeast/mold compared with the control. Cheese samples contained no detectable levels of coliforms (< 10 cfu/g). The HPLC data showed quantitative recovery of lutein during the storage period, and no lutein degradation products were identified. These results indicate that lutein, a functional additive with purported ability to prevent or reduce the onset of AMD, can be incorporated into cheese adding value to this product.     

Effects of lutein and zeaxanthin on aspects of eye health

Lutein and zeaxanthin are members of the oxygenated carotenoids found particularly in egg yolks and dark‐green leafy vegetables. A great deal of research has focused on their beneficial roles in eye health. The present article summarises the current literature related to the bioactivity of these carotenoids, emphasising their effects and possible mechanisms of action in relation to human eye health. Available evidence demonstrates that lutein and zeaxanthin are widely distributed in a number of body tissues and are uniquely concentrated in the retina and lens, indicating that each has a possible specific function in these two vital ocular tissues. Most of epidemiological studies and clinical trials support the notion that lutein and zeaxanthin have a potential role in the prevention and treatment of certain eye diseases such as age‐related macular degeneration, cataract and retinitis pigmentosa. The biological mechanisms for the protective effects of these carotenoids may include powerful blue‐light filtering activities and antioxidant properties. Although most studies point towards significant health benefits from lutein and zeaxanthin, further large‐scale randomised supplementation trials are needed to define their effects on ocular function in health and disease. Copyright © 2009 Society of Chemical Industry     

制备万寿菊叶黄素技术研究进展

由于叶黄素(lutein)是自然界广泛存在的二羟基类胡萝卜素,也是人眼视网膜黄斑色素主要组成部分。叶黄素可有效预防并辅助治疗老年性黄斑退化病和白内障等眼部疾病,其在生物活性物质利用领域有广泛的应用前景。万寿菊是工业上提取分离叶黄素的理想工业原料。本文从万寿菊叶黄素提取专用品种、叶黄素分子结构及叶黄素稳定性等6个方面综述了近年来国内外有关万寿菊叶黄素的研究工作,并进行了前景展望。     

叶黄素的视力保护作用及提取工艺

叶黄素(lutein)是一种含氧的类胡萝卜素,分布在黄斑区和整个视网膜,具有蓝光屏蔽和抗氧化功能,具有重要的保护视力的作用。本文介绍了叶黄素与黄斑变性、白内障的关系,揭示其对视觉发育及功能的影响,并总结了叶黄素的提取技术,通过示例探讨了提取条件优化及工艺特点,最后展望了黄素的及提取方法与市场前景。     

纳米分散高含量叶黄素微囊化的研究

叶黄素不溶于水,微溶于植物油,有限的溶解性和对氧化的高敏感性,阻碍了合成得到的粗产品在食品和饲料染色中的直接使用,为增加得色量并增加可吸收性和生物利用率,必须将活性物质的粒径减小到10μm以下,甚至有的达到了纳米级,因为叶黄素的着色效力和生物利用率与其在介质中的粒径和分散性直接相关,为此本文研究了以叶黄素为原料,通过单因素实验,分析了油、溶解温度、时间、喷雾干燥工艺对微囊化叶黄素产品的影响,确定了瞬时高温油溶和喷雾冷凝法微囊化叶黄素新工艺;并通过正交实验,从产品感观质量和稳定性入手,确定了合理的水溶性5%叶黄素微囊化产品配方,解决了高含量叶黄素产品的稳定性、异构和高脂溶难吸收的三大难题。     

高等植物叶黄素合成代谢与调控机制

叶黄素(lutein)是C₄₀的萜类化合物,结构中含紫罗酮环,广泛存在于自然界中。叶黄素是高等植物光系统中主要的光合色素,能捕获光能供叶绿素进行光合代谢。叶黄素在预防视网膜黄斑变性、白内障、癌症及心血管疾病等方面有重要作用。本文综述高等植物叶黄素的生物代谢途径与其关键酶的作用和调控机制,并对今后的重点探索方向和优先研究内容提出建议。     

Postprandial evolution of the carotenoid content in the triacylglycerol-rich lipoprotein fraction after a single ingestion of virgin olive oil in humans

Carotenoids bioavailability in humans is highly influenced by several factors, including presence and kind of fat that is ingested in the daily diet. This trial was focussed on those two driving factors of carotenoid absorption, analysing the postprandial carotenoid evolution in 12 healthy volunteers supplied with a fundamental edible component of the Mediterranean diet: virgin olive oil. This is a fat with a balanced triacylglycerol composition containing concurrently carotenoids like β-carotene and lutein, which provide a functional feature in the human organism. The achieved results showed two different responses in the controlled volunteers: five of them increase, significantly, their carotenoid level in the triacylglycerol-rich lipoprotein fraction while the remaining did not accumulate any of the supplied carotenoids at detectable amounts. A different carotenoid metabolism was observed in the first group as only lutein (a nonprovitamin A carotenoid) increased its concentration in the lipoprotein fraction. The kind of fat supplied together with vitamin A status and antioxidant content of the individuals could explain the different responses.     

A review on factors influencing bioaccessibility and bioefficacy of carotenoids

Vitamin A deficiency is one of the most prevalent deficiency disorders in the world. As shown by many studies plant food based approaches have a real potential on prevention of vitamin A deficiency in a sustainable way. Carotenoids are important as precursors of vitamin A as well as for prevention of cancers, coronary heart diseases, age-related macular degeneration, cataract etc. Bioaccessibility and bioefficacy of carotenoids are known to be influenced by numerous factors including dietary factors such as fat, fiber, dosage of carotenoid, location of carotenoid in the plant tissue, heat treatment, particle size of food, carotenoid species, interactions among carotenoids, isomeric form and molecular linkage and subject characteristics. Therefore even when carotenoids are found in high quantities in plant foods their utilization may be unsatisfactory because some factors are known to interfere as negative effectors.     

Intestinal absorption of dietary carotenoids

The assessment of carotenoid bioavailability has long been hampered by the limited knowledge of their absorption mechanisms. However, recent reports have elucidated important aspects of carotenoid digestion and absorption. Disruption of food matrix and increasing amounts of fat seem to enhance the absorption of carotenes to a larger extent than that of xanthophylls. Comparing different carotenoid species, xanthophylls seem to be more easily released from the food matrix and more efficiently micellized than the carotenes. On the other hand, carotenes are more efficiently taken up by the enterocytes. However, carotenoid emulsification and micellization steps are largely affected by the food matrix and dietary components, being the main determinant of carotenoid bioavailability from foodstuffs. Although the intestinal uptake of carotenoids has been thought to occur by simple diffusion, recent studies reported the existence of receptor-mediated transport of carotenoids in enterocytes. Comparisons between the intestinal absorption of a wide array of carotenoids would be useful to elucidate the absorption mechanism of each carotenoid species, in view of the recent indications that intestinal carotenoid uptake may involve the scavenger receptor class B type I and possibly other epithelial transporters. The unraveling of the whole mechanism underlying the absorption of carotenoids will be the challenge for future studies.     

叶黄素的保健功能

叶黄素作为一种天然色素，广泛存在于自然界中。大量的流行病学证据表明，叶黄素在预防人类某些癌症和慢性病的发生方面起着重要的作用，是目前国际上功能性食品成分研究中的一个热点。本详细地介绍了叶黄素的结构、性质及生理功能方面的研究进展，并对其将来在食品中的应用加以展望。     

叶黄素酯——健康视力的保护神

<正>良好的营养是保持一生拥有健康视力的基本条件。研究发现,叶黄素是一种黄色的类胡萝卜素,同时也是强抗氧化剂,对眼睛健康具有特别的重要性。眼保健与老年性黄斑变性叶黄素和玉米黄质(一种类胡萝卜素)在维持视网膜黄斑(主管人的精细视力)的正常生理功能中扮演着重要的角色。它们组成了视网膜黄斑色素,同时能过滤对眼睛有害的蓝光,并作为抗氧化剂消除自由基的侵害。摄入增补剂和富含叶黄素的食物可增加黄斑色素的密度,从而降低罹患老年性黄斑变性(AMD)的风险。