硒的环境生物学及含硒食品

硒是人体必需的微量元素之一,对人类健康有着重要意义。机体硒的来源主要是食物,综述了硒的环境生物学及含硒食品的研究进展。     

食品原料硒强化与富硒功能食品研究

硒是人体必需的微量元素。硒缺乏会导致人体易衰老、免疫力下降,并引起癌症、高血压、肝硬化等多种疾病。因此,适当补硒有利于健康。日常食用天然食品原料,并不能达到人体每天所需要的硒摄入量,可能导致硒缺乏。利用硒强化技术开发富硒食品原料,并在此基础上研发各种富硒功能食品,将成为满足我国居民硒需求的重要举措。     

硒的生理学功能及富硒强化食品的研究进展

硒是人体必需的微量元素之一,本文综述了元素硒对人体的重要生理功能、硒缺乏症与硒中毒、硒的推荐摄入量及富硒食品的开发现状,并指出了膳食硒的研究方向。     

硒的生理功能及富硒产品研究进展

硒是人体必需的微量元素,具有降血压、调节免疫、防癌抗癌、抗动脉硬化等重要的生理作用,适量补充硒可有效提高机体的抗氧化能力、增强机体代谢和免疫力。该文综述硒的生理作用及我国富硒产品的开发现状并进行展望,为硒的进一步深入研究和科学、有方向性开发富硒食品提供依据。     

微量元素硒的生理学功效及富硒功能性食品简介

硒可以保护心肌,防治克山病、大骨节病、肝病及多种癌症等。随着人们对健康程度的关注越来越高,硒对人体健康的作用也成为人们越来越被人们所重视,各种富硒食品逐渐走入了人们的日常生活。文章将对硒的生理学功效及富硒强化食品做简单的介绍。     

硒与维生素补剂和富硒食品在肿瘤预防上的应用

硒与维生素补剂和富硒食品在肿瘤预防上的应用唐品志中国科学院生物物理研究所北京１００１０１硒的缺乏和心脏病等某些疾病的关系，已进行了大量的研究。人体硒营养水平与癌症发生的关系，是值得注意的。“硒与癌”的前沿性研究，“硒与癌”的干预性试验，近年来肿瘤与营...     

我国富硒食品的研究进展

本文分析了硒强化剂的特点和硒强化食品的现状,阐述了天然富硒保健食品和人工转化的富硒营养食品的研究进展。     

硒与癌

硒与癌陆肇海中国农科院食品工业研究所北京１０００８１硒与癌密切相关，土壤中缺硒的地区，人们的癌的发生和死亡率高；在低硒土壤中生长的作物含硒量低，食用低硒食物人群中癌的发生和死亡率也高；因摄入硒少而导致血液中硒含量低，血硒水平低的人群癌症发生和死亡率高...     

富硒食品开发与应用

人类自1817年发现硒元素已有近200年的历史,最早硒被认为是一种毒素(致癌物质)和污染元素。过量食用含硒的食物可引起人或动物硒中毒或致癌。19世纪50年代时人们发现动物缺硒会导致肝坏死和肌营养不良。因此,人们开始研究硒的毒性转为研究它的营养性。70年代科学家研究证明硒     

食品中微量硒测定方法研究进展

硒具有延缓衰老、增强免疫力、预防癌症等功效。人体获取硒的主要来源是食品,本文从光学分析法、电化学分析法、色谱学分析法、联用技术等方面对食品中硒含量检测方法进行了综述。并同时介绍了近年来常用于硒检测的联用技术,以期为食品中硒含量测定方法研究提供参考。      

Bio-fortification and isotopic labelling of Se metabolites in onions and carrots following foliar application of Se and Se

The aims were to bio-fortify onions by foliar application of selenium (Se) and to intrinsically label bioactive Se-metabolites in onion and carrot by enriched, stable ⁷⁷Se for use in human physiological studies. Onion bulbs and leaves were enriched in Se by repeated foliar spraying of 10 or 100 μg Se ml⁻¹ solutions of sodium selenite (Se(IV)) or sodium selenate (Se(VI)). ICP-MS analysis of onion leaves and bulbs showed that the Se concentration was enhanced by up to a factor of approximately 50 and 200 in bulbs and leaves, respectively. HPLC–ICP-MS analysis of proteolytic plant extracts showed that foliar application of Se(IV) gave rise to bio-synthesis of a higher fraction of the desired organic Se species and was better tolerated by the plants than Se(VI). Based on these findings onions and carrots were bio-fortified by foliar application of a solution of ⁷⁷Se(IV) that was enriched to 99.7% as ⁷⁷Se. The ⁷⁷Se- labelled metabolites in onions were predominantly γ-glutamyl-⁷⁷Se-selenomethyl-selenocysteine (γ-glu-Me⁷⁷SeCys), ⁷⁷Se-methylselenocysteine (Me⁷⁷SeCys) and ⁷⁷Se-selenomethionine (⁷⁷SeMet). Furthermore, we report here for the first time the finding in carrots of the bioactive Me⁷⁷SeCys, the identity of which was verified by HPLC–ESI-MS/MS.     

Speciation of Se and DOC in soil solution and their relation to Se bioavailability

A 0.01 M CaCl(2) extraction is often used to asses the bioavailability of plant nutrients in soils. However, almost no correlation was found between selenium (Se) in the soil extraction and Se content in grass. The recently developed anion Donnan membrane technique was used to analyze chemical speciation of Se in the 0.01 M CaCl(2) extractions of grassland soils and fractionation of DOC (dissolved organic carbon). The results show that most of Se (67-86%) in the extractions (15 samples) are colloidal-sized Se. Only 13-34% of extractable Se are selenate, selenite and small organic Se (<1 nm). Colloidal Se is, most likely, Se bound to or incorporated in colloidal-sized organic matter. The dominant form of small Se compounds (selenate, selenite/small organic compounds) depends on soil. A total of 47-85% of DOC is colloidal-sized and 15-53% are small organic molecules (<1 nm). In combination with soluble S (sulfur) and/or P (phosphor), concentration of small DOC can explain most of the variability of Se content in grass. The results indicate that mineralization of organic Se is the most important factor that controls Se availability in soils. Competition with sulfate and phosphate needs to be taken into account. Further research is needed to verify if concentration of small DOC is a good indicator of mineralization of soil organic matter.     

Extraction of Se species in buckwheat sprouts grown from seeds soaked in various Se solutions

The transformation of selenium (Se) in buckwheat sprouts grown from seeds soaked in various Se solutions (Se-methionine (10 mg Se L⁻¹), selenate or selenite (5, 10, 20 mg Se L⁻¹)) was investigated. The extraction procedure was optimised by (a) using optimal extraction media (water, phosphate buffer, 0.1, 0.2, 0.3 M HCl, the enzyme protease alone or in combination with cellulase, amylase or lipase), and by (b) optimising the ratio between sample and enzyme. For Se speciation analysis extracts with the highest percentage of soluble Se were analysed, and additionally the stability of the extracts was investigated. The results showed that uptake of Se by sprouts was dependent on the form and concentration of Se in the solution used for soaking. Optimal extraction efficiencies were obtained by hydrolysis with 0.3 M HCl and protease. Selenate (23.7–29.7% from Se(VI) sprouts and in trace amounts from Se(IV) and SeMet sprouts), Se-methionine (2.4–7.9%) and selenite (traces) were detected in all supernatants, regardless of soaking solution.     

乳酸菌源纳米硒对小鼠抗氧化性能的影响

硒是人体必需的重要微量元素之一,在生物活性和毒性之间范围极端狭窄,容易接近或进入了硒的毒性范围,但纳米硒具有较强的高效高安全优势。本研究利用对亚硒酸钠有较强耐受性的一株编号LA4乳酸菌株进行亚硒酸钠还原反应,制备纳米硒。通过对昆明系小鼠灌胃不同浓度纳米硒进行实验:对照组、低剂量组、中剂量组和高剂量组,研究分析乳酸菌LA4源纳米硒对小鼠抗氧化性能的影响。经SEM-EDX测试得到乳酸菌LA4能将亚硒酸钠还原成纳米尺寸的球状颗粒,粒径基本≤200nm。乳酸菌LA4源纳米硒对小鼠全血、睾丸中的GSH-PX的活性具有极显著提高作用（p<0.01）,对小鼠大脑、肝脏以及脾脏等重要器官组织T-AOC和POD活力也具有极显著提高作用（p<0.01）;乳酸菌LA4源纳米硒极显著的提高小鼠血清中T-SOD活力（p<0.01）,有利于降低小鼠血清及重要器官组织的MDA含量;因此乳酸菌LA4源纳米硒对小鼠抗氧化性能具有提高作用,并且乳酸菌LA4源纳米硒添加水平就算增加到1.0mg/kg·bw时,仍对小鼠抗氧化性能具有提高作用。      

不同添加时间和添加量组合对酵母富硒效果的影响

以亚硒酸钠为硒源,在酵母的培养过程中,于不同的时间组合添加不同量的亚硒酸钠,以研究不同添加时间和添加量对酵母富硒的影响。实验结果表明:在发酵过程中的5h、8h、11h,添加一定量的亚硒酸钠使其在发酵液中的浓度分别达到5mg/L、10mg/L、15mg/L时,酵母的产量和富硒效果最佳。     

大豆喷施硒肥效应的初步研究

不同结荚习性大豆品种间株型特征差异明显，亚有限结荚习性品种的上部叶片呈典型的狭长叶，株高、节数和单株叶片数较多，喷硒后干物质积累量比有限结荚习性品种高5％，是导致其积硒量高于有限结荚习性品种主要因素。硒肥处理后，有限结荚习性品种的产量随浓度增加有提高的趋势，亚有限结荚习性品种则随浓度增加产量下降。同一品种大豆籽粒硒含量随喷施硒肥浓度的提高而增加，品种间因基因型差异存在明显的积累硒能力的差异。     

乳酸菌富集硒的条件研究

研究了保加利亚乳杆菌将无机态微量元素硒富集转化为细胞内的有机态微量元素硒的条件。正交试验结果表明:培养基中亚硒酸钠浓度为主要影响因素,培养温度、培养时间和接种量为次要影响因素。在3个次要因素中,培养温度的影响是较主要的。最佳富集条件为亚硒酸钠浓度90μg/ml、培养温度37℃、培养时间60h、接种量8%。细胞富集的有机态硒占总富集量的80%以上。     

红色单质硒/DOX-淀粉复合颗粒的制备及抗肿瘤协同效果分析

合成了红色单质硒-多柔比星-淀粉复合纳米颗粒,并作用于肝癌BEL7404细胞,采用MTT法检测其对细胞的生长抑制情况。将Na2SeO3还原成红色单质硒,然后通过疏水作用结合到装载有多柔比星（DOX）的淀粉纳米颗粒的表面,形成红色单质硒-多柔比星-淀粉复合颗粒（Se/DOX-StNP）;采用Zeta-size粒度仪检测其颗粒分布和表面电荷,颗粒直径范围为50～80nm,表面电荷为-13.9mV;透射电镜结果显示具有明显核壳结构;颗粒作用于肝癌BEL7404细胞,其细胞生长抑制率比相当量的红色单质硒和DOX-淀粉纳米颗粒（DOX-StNP）的细胞抑制率总和高出15%,展现了红色单质硒促进DOX抗肿瘤活性的协同效果。结果表明,复合制剂实现不同药物的同时给药,有较好的抗肿瘤效果,这将为抗肿瘤药物的药剂学研究提供新的思路。      

硒、锌对甘蓝型油菜产量和营养品质的影响

采用土培试验,以甘蓝型油菜为供试作物,研究了陕西渭北旱塬低硒、低锌土壤上,硒、锌对甘蓝型油菜产量和营养品质的影响。试验结果表明,硒对油菜生物量和产量没有明显的影响。锌或硒锌配施对油菜生物量和产量有增加趋势;施硒促进油菜籽对钾、硒元素的吸收累积,而在一定程度上抑制了磷、硫、钙和镁元素的吸收。施锌促进油菜对钾、钙、铁、锰、铜、锌、硼的吸收累积,而对氮、硫的吸收有抑制作用。硒锌配合施用有利于促进油菜对硒、锌的吸收累积,而对铁的吸收有一定的抑制作用;施硒对油菜籽含油量、芥酸有增加趋势,对蛋白质、硫甙含量有降低趋势。施锌对油菜籽含油量有增加趋势,对蛋白质、硫甙、芥酸有降低趋势。硒锌配施,油菜含油量、蛋白质、硫甙无变化,芥酸明显下降。     

Effect of pH on aqueous Se(IV) reduction by pyrite

Interaction of aqueous Se(IV) with pyrite was investigated using persistently stirred batch reactors under O2-free (<1 ppm) conditions at pH ranging from 4.5 to 6.6. Thermodynamic calculations, an increase in pH during the experiments, and spectroscopic observation indicate that the reduction of aqueous Se(IV) by pyrite is dominated by the following reaction: FeS2+3.5HSeO3?+1.5H+=2SO4(2?)+Fe2++3.5Se(0)+2.5H2O. The released Fe(II) was partitioned between the bulk solution and pyrite surface at pH≈4.5 and 4.8, with the Fe2+ density at pyrite-solution interface about 4 orders of magnitude higher than that in the bulk solution, while iron oxyhydroxide precipitated at pH≈6.6, resulting in the decrease of dissolved iron. In the Se(IV) concentration range of the experiments, aqueous Se(IV) reduction rate follows the pseudofirst order which is in the form of ln mSe(IV)=?k′t+ln mSe(IV)0, where k′ is apparent rate constant combining the rate constant k and pyrite surface area to mass of solution ratio (A/M). And the aqueous Se(IV) reduction rate constant for a standard system (k) with 1 m2 pyrite surface area per 1 kg solution was obtained to be 1.65×10(?4) h(?1), 3.28×10(?4) h(?1), and 4.76×10(?4) h(?1) at pH around 4.5, 4.8, and 5.1, respectively. The positive correlation between reaction rate and pH disagrees with the theories that protons are consumed when HSeO3? is reduced to Se0, and negative charge density on pyrite surface increases as pH increases. Thus, a ferrous iron mediated electron transfer mechanism is proposed to operate during the reduction of aqueous Se(IV) by pyrite. pH and iron concentration affect significantly on Se(IV) reaction rate and reaction product.