Dietary lutein and zeaxanthin: possible effects on visual function

Of the many carotenoids circulating in human sera, only lutein and zeaxanthin are accumulated throughout the tissues of the eye. Within the eye, they reach their highest concentration in the central retina, where they are clinically referred to as the macula lutea. Lutein and zeaxanthin, more commonly referred to as macular pigments, may serve a variety of roles in the specialized vision of higher primates. This paper reviews recent studies investigating the influence of macular pigments on human visual performance. Such studies have offered insight into why lutein and zeaxanthin are uniquely concentrated in ocular tissues.     

人眼黄斑色素密度与对比敏感度功能的关系

目的研究黄斑色素密度与对比敏感度功能之间的关系,探讨黄斑色素对视功能的影响。方法采用异色闪烁光度仪对116例正常香港青年的右眼进行黄斑色素密度测量。挑选黄斑色素密度值超过0.90和低于0.40的受试者,将他们分为高黄斑色素密度组和低黄斑色素密度组。采用VSG系统软件对两组右眼进行空间、时间对比敏感度功能测量。结果116例受试者右眼黄斑色素密度值为0.64±0.30。高密度组在各个空间频率与时间频率下的对比敏感度值都高于低密度组;高、低黄斑色素密度组的条栅视力分别为(33.01±3.35)c/d和(30.83±2.88)c/d;闪光融合频率分别是(37.69±6.82)Hz和(36.24±5.00)Hz。但两组空间、时间对比敏感度功能差异无显著性。结论为了进一步证实黄斑色素与视功能之间的关系,需要在这一方面进行更多的研究。     

叶黄素与老年性黄斑变性的防治

老年性黄斑变性(AMD)是老年人的主要致盲性疾病之一。叶黄素作为高能量蓝光滤过器和抗氧化剂,能保护黄斑区和视网膜免受光损伤。通过食用各类水果、蔬菜和鱼类增加叶黄素摄入量可预防AMD。     

叶黄素对人肝癌细胞HepG2的抑制作用及其机制研究

目的研究叶黄素对人肝癌细胞的抑制作用并探讨其可能机制。方法以HepG2人肝癌细胞株和L02正常人肝细胞株为研究对象,设叶黄素低、中、高剂量组(20、40、80 mol/L)和溶剂对照组。常规细胞培养后进行细胞计数、MTT法测定细胞存活率、DCFH-DA法测定ROS活性、HPLC法测定ATP含量、RT-PCR测定Bax mRNA及p53mRNA表达水平。结果 HepG2细胞经叶黄素干预处理后,低、中、高剂量组的细胞存活率显著降低(P<0.05),并且随干预时间的增加而持续降低,ROS水平和ATP含量显著降低(P<0.05);高剂量组的Bax mRNA表达和中、高剂量组的p53 mRNA表达显著增加(P<0.05)。而L02细胞经叶黄素干预处理后,细胞存活率和ATP含量均无显著性变化。结论叶黄素能抑制人肝癌细胞的生长,其机制可能与叶黄素清除细胞内ROS、抑制肝癌细胞ATP生成及上调凋亡基因Bax和p53 mRNA的表达有关。[营养学报,2012,34(4):332-335]     

Lifestyle modification,nutritional and vitamins supplements for age‐related macular degeneration

Purpose: To provide a systematic review of the published studies pertaining to the lifestyle modification, dietary, nutritional and vitamins supplements for preventing occurrence or halting deterioration of age‐related macular degeneration (AMD). Methods: The literature searches from 1990 to December 2010 with following keywords, ‘age related macular degeneration’, ‘nutrition’, ‘antioxidant’, ‘diet’ and ‘vitamins supplements’ using search engines Pubmed, Google Scholar, Medline and the Cochrane Library. Meta‐analyses, population‐based cohort studies and case‐controlled trials were reviewed, whereas small cases series, case reports, commentaries, abstracts in proceedings or personal observations were excluded. Results: Smoking and obesity are identified risk factors for AMD. High dietary intakes of omega‐3 fatty acids, and macular xanthophylls lutein and zeaxanthin have been associated with a lower risk of prevalence and incidence in AMD. Vitamin B and extracts from wolfberry, Gingko biloba and berry anthocyanins were also subjects of intense research interests, but there has been no concluding scientific evidence yet. The Age‐Related Eye Disease study (AREDS) is the only large‐scale randomized controlled clinical trial to show beneficial effect of AREDS formulation of vitamins C, E, beta‐carotene and zinc with copper in reducing the risk progression to advanced AMD in patients with intermediate AMD or with advanced AMD in one eye. Conclusion: Quit smoking is an important advice to patients to prevent or slow the progress of AMD. There is no recommendation for routine nutritional or vitamins supplementation for primary prevention. However, patients with documented intermediate risk of AMD or advanced AMD in one eye are recommended to take AREDS‐type vitamin supplements.     

Carotenoid lutein protects rats from paracetamol‐, carbon tetrachloride‐ and ethanol‐induced hepatic damage

Objectives Carotenoids are a class of natural fat‐soluble pigments that are found in many fruits and vegetables. Consumption of a diet rich in carotenoids has been epidemiologically correlated with a lower risk for several diseases. In the present study the carotenoid lutein (3,3′‐dihydroxy‐β,ε‐carotene) was evaluated for its hepatoprotective activity in rats. Methods Paracetamol, 20% ethanol and carbon tetrachloride were used to induce liver toxicity. Key findings Levels of serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase and alkaline phosphatases, which were increased in the serum, were found to be significantly reduced by the treatment of lutein in a dose‐dependent manner, indicating that lutein may reduce the hepatotoxicity induced by these agents_. Serum bilirubin was also significantly lower in lutein‐treated groups compared with control. Increased lipid peroxidation, conjugated diene and hydroperoxides in the liver tissue produced by the administration of paracetamol were found to be reduced in the lutein‐treated groups. Levels of antioxidant enzymes, like superoxide dismutase, catalase, glutathione peroxidase and glutathione, were found to be increased in lutein‐treated groups compared with control group during alcohol‐ and CCl₄‐induced liver toxicity. Hydroxyproline, which is an indicator of fibrosis in liver tissue, was high in the ethanol‐treated control group. Hydroxyproline levels were decreased by simultaneous lutein administration. Conclusions Histopathological evidence confirmed the protection offered by lutein from the tissue damage caused by hepatotoxins. The hepatoprotective action may be due to lutein's ability to scavenge reactive oxygen radicals.     

北京地区常见蔬菜中叶黄素、玉米黄素和β-胡萝卜素的测定及其含量

目的测定分析常见蔬菜中叶黄素、玉米黄素和β-胡萝卜素的含量。方法采用高效液相色谱法Develosil C30柱;流动相A:乙腈:甲醇=75:25,B:甲基叔丁基醚,梯度洗脱;紫外检测器,检测波长480nm检测北京市常见市售蔬菜中叶黄素、玉米黄素和β-胡萝卜素的含量。结果叶黄素、玉米黄素和β-胡萝卜素保留时间分别为10.355、10.732和20.789min,实现基线分离。深绿色叶菜,如苋菜、芹菜叶、香菜、菠菜、小白菜中叶黄素含量最为丰富。玉米黄素仅在黄花菜(干)中检出。熟制后,各类蔬菜的平均叶黄素和β-胡萝卜素含量呈上升趋势。结论绿色蔬菜,尤其是深绿色叶菜,是叶黄素、β-胡萝卜素的主要膳食来源,摄入熟制后的蔬菜有利于增加叶黄素、玉米黄素的摄入量和生物利用率。     

叶黄素对D-半乳糖致氧化损伤小鼠HO-1、TLR4表达的影响

目的研究叶黄素缓解D-半乳糖诱导小鼠氧化应激损伤的作用机制。方法 48只昆明种小鼠随机分为D-半乳糖模型对照组、叶黄素低剂量组(10mg/kg·d)、叶黄素高剂量组(40mg/kg·d)和正常对照组。6周后观察小鼠肝组织活性氧(ROS)、一氧化氮(NO)含量,总一氧化氮合酶(TNOS)、诱导型一氧化氮合酶(iNOS)和线粒体ATP酶(ATPase)活性,RT-PCR法检测血红素氧合酶(HO-1)和toll样受体4(TLR4)mRNA表达水平。结果叶黄素低、高剂量组小鼠肝组织ROS含量低于模型对照组(P0.01);低、高剂量组线粒体Na+-K+-ATP酶及高剂量组线粒体Ca2+-ATP酶活性高于模型对照组(P0.05);高剂量组TNOS、iNOS活性及NO含量低于模型对照组(P0.05);高剂量组小鼠肝HO-1mRNA表达高于模型对照组(P0.05),叶黄素低、高剂量组TLR4mRNA表达均低于模型对照组(P0.01)。结论叶黄素降低D-半乳糖小鼠氧化应激效应可能与其提高HO-1表达和下调TLR4mRNA表达有关。