Optimized Biocatalytic Synthesis of 2-Selenopyrimidine Nucleosides by Transglycosylation**

Selenium-modified nucleosides are powerful tools to study the structure and function of nucleic acids and their protein interactions. The widespread application of 2-selenopyrimidine nucleosides is currently limited by low yields in established synthetic routes. Herein, we describe the optimization of the synthesis of 2-Se-uridine and 2-Se-thymidine derivatives by thermostable nucleoside phosphorylases in transglycosylation reactions using natural uridine or thymidine as sugar donors. Reactions were performed at 60 or 80 °C and at pH 9 under hypoxic conditions to improve the solubility and stability of the 2-Se-nucleobases in aqueous media. To optimize the conversion, the reaction equilibria in analytical transglycosylation reactions were studied. The equilibrium constants of phosphorolysis of the 2-Se-pyrimidines were between 5 and 10, and therefore differ by an order of magnitude from the equilibrium constants of any other known case. Hence, the thermodynamic properties of the target nucleosides are inherently unfavorable, and this complicates their synthesis significantly. A tenfold excess of sugar donor was needed to achieve 40−48 % conversion to the target nucleoside. Scale-up of the optimized conditions provided four Se-containing nucleosides in 6–40 % isolated yield, which compares favorably to established chemical routes.     

S/Se dual-doping promotes the formation of active Ni/Fe oxyhydroxide for oxygen evolution reaction of (sea)water splitting

Surface reconstruction produces metal oxyhydroxide (1OOH) active sites, and promoting surface reconstruction is essential for the design of OER electrocatalysts. In this paper, we reported that a large amount of active NiFeOOH was generated in-situ on the surface of nickel-iron sulfide selenide, thus exposing more active sites and efficiently catalyzing OER. In 1 M KOH solution, NiFeOOH(S,Se) achieves an ultra-low overpotential of 195 mV at the current density of 10 mA cm^?2, and the Tafel slope is only 31.99 mV dec^?1, showing excellent catalytic performance. When the current density is 100  mA cm^?2, the over-potential of NiFeOOH(S,Se) in KOH + seawater solution is 239 mV, which is almost equivalent to 231 mV in KOH solution. The excellent OER stability of the NiFeOOH(S,Se) catalyst in alkaline electrolytes was confirmed, and the overpotential did not change significantly after 4 days of testing in KOH + seawater solution.     

Biofortification with selenium and lithium improves nutraceutical properties of major winery grapes in the Midwestern United States

Enriching the micronutrients, selenium (Se) and lithium (Li), in grapes to improve their nutraceutical properties were implemented by foliar application of organic fertiliser rich in Se and Li onto five grape cultivars. The effects of this biofortification on vine vigour, fruit quality, overall micronutrients and phenolic compounds also were investigated. Agronomic biofortification was found greatly increased the Se and Li content in the whole grape by multiple times, meanwhile it did not significantly affect the vine vigour and fruit quality of grapes. However, the biofortification did impact the Ionome (including all the mineral nutrients and trace elements) and phenolic compounds in grapes and this varied among cultivars. This study demonstrated foliar spray of organic Se/Li fertiliser was a very effective strategy to biofortify these micronutrients in grape berries, particularly in the skin, and therefore might be a promising strategy to increase the consumption and awareness of these grapes.     

电感耦合等离子体质谱法测定牛初乳粉中痕量硒的干扰探讨

目的 分析样品基体给检测结果造成的增敏效应影响,建立一种能消除待测样品中基体的干扰,从而准确测定痕量硒的电感耦合等离子体质谱的检测方法。方法 样品经硝酸消解后, 采用标准加入法,标准溶液加入的体积不大于待测液体积2%的前提下,在氦气模式下以元素特定质量数定性,以待测元素质谱信号与内标元素质谱信号的强度比与待测元素的浓度成正比进行定量分析。结果 样品基底对硒有增敏效果采用标准加入法能很好消除样品基底干扰,检测5种标准物质的硒含量均在标示值范围内。工作曲线相关系数达到0.998,精密度试验的相对标准偏差为3.2%。结论 该方法相对外标法能更准确对痕量硒进行定量,适合测定基底复杂存在干扰的样品,对相同或相近的样品可以共用相同工作曲线测定硒含量。     

硒多糖酸奶贮藏期间的理化特性研究

为研究硒多糖对酸奶4℃贮藏25d内理化特性的影响,将0.06%硒多糖添加到纯牛奶中通过乳酸菌发酵制得硒多糖酸奶,测定硒多糖酸奶和对照酸奶中持水力、酸度、乳酸菌及硒含量等指标。结果表明:低温贮藏5-25 d内,对照酸奶和硒多糖酸奶持水力比较稳定;当贮藏时间为第15 d时,硒多糖酸奶持水力显著高于对照酸奶(P<0.05)。酸度随着贮藏时间的延长而显著增加(P<0.05),硒多糖酸奶和对照酸奶之间酸度无明显差异性。乳酸菌数量于贮藏时间5-25d呈现明显下降趋势(P<0.05),硒多糖酸奶在贮藏时间1d、10d和15d时乳酸菌数量显著低于对照酸奶(P<0.05)。低温贮藏期间酸奶硒含量比较稳定,且硒多糖酸奶硒含量是对照酸奶的10倍左右。硒多糖能改善酸奶在贮藏期间的一些理化特性。     

New Formulation of a Methylseleno-Aspirin Analog with Anticancer Activity Towards Colon Cancer

Aspirin (ASA) has attracted wide interest of numerous scientists worldwide thanks to its chemopreventive and chemotherapeutic effects, particularly in colorectal cancer (CRC). Incorporation of selenium (Se) atom into ASA has greatly increased their anti-tumoral efficacy in CRC compared with the organic counterparts without the Se functionality, such as the promising antitumoral methylseleno-ASA analog (1a). Nevertheless, the efficacy of compound 1a in cancer cells is compromised due to its poor solubility and volatile nature. Thus, 1a has been formulated with native α-, β- and γ-cyclodextrin (CD), a modified β-CD (hydroxypropyl β-CD, HP-β-CD) and Pluronic F127, all of them non-toxic, biodegradable and FDA approved. Water solubility of 1a is enhanced with β- and HP- β-CDs and Pluronic F127. Compound 1a forms inclusion complexes with the CDs and was incorporated in the hydrophobic core of the F127 micelles. Herein, we evaluated the cytotoxic potential of 1a, alone or formulated with β- and HP- β-CDs or Pluronic F127, against CRC cells. Remarkably, 1a formulations demonstrated more sustained antitumoral activity toward CRC cells. Hence, β-CD, HP-β-CD and Pluronic F127 might be excellent vehicles to improve pharmacological properties of organoselenium compounds with solubility issues and volatile nature.     

黄豆发芽过程中Zn、Co和Se的富集及交互作用

本研究以黄豆发芽为手段，采用具有交互关联功能的均匀设计U10(103)表设计并实施了Zn、Co、Se三种人体微量元素在黄豆芽菜生长过程的生物富集实验，评价了芽菜样品的Zn、Co和Se富集量以及有机化富集量，研究了不同Zn、Co、Se外源浓度组间样品生物富集量与各元素外源浓度的回归关系，发现了各元素外源浓度对Zn、Co和Se富集的交互作用以及Zn、Co和Se的富集规律。结果表明：交互作用发生在芽菜生长后期（30 h后），[Zn×Co]和[Co×Se]呈现协同作用，外源Se通过双重协同作用促进芽菜吸收Zn，[Zn×Se]和[Zn×Co×Se]呈现拮抗作用，外源Zn通过双重拮抗作用抑制芽菜对Se的吸收；芽菜生长前期（30 h前）元素的有机转化率低，元素的富集是以物理渗析吸收为主，生长后期（30 h后）则通过各元素外源浓度的交互作用产生有机化富集，综合评价结果表明处理方案3、6和9对获得富Zn、Co和Se的芽菜特别有效，特别是处理方案3（Zn2+、Co2+混合液：[Zn2+]=1200 μg/L，[Co2+]=30 μg/L；Se4+溶液：[Se4+]=180 μg/L）45 h的样品达到了最优综合Zn、Co和Se富集：Zn2+ =8.58 mg/kg，Co2+=63.10 μg/kg，Se4+=48.30 μg/kg，有机化率分别为Zn 49.50%，Co 25.94%，Se 56.25%，三个元素的富集总量基本同时达到了Zn、Co和Se在中国膳食指南中推荐摄入量，对于Zn、Co和Se多元富集健康蔬菜的生产实际具有直接的参考作用。     

水泥窑协同处置固废中硒元素的测定方法探讨

本文使用原子荧光光谱仪对水泥窑协同处置固废中的硒元素进行了测定方法开发工作。方法中采用了倒王水沸水浴对固体废弃物进行消解溶样,以10%盐酸作为载流液,0.4%氢氧化钾和1.2%硼氢化钾作为还原剂,铁氰化钾作为掩蔽剂,以消除各种离子的干扰。优化了原子荧光光谱仪的测定条件,对标准样品和固废样品进行了检测。方法检出限为0.04μg/L,相对标准偏差为3.0%~10.1%。固废和污泥中加标回收率为82.8%~102.5%。     

原子荧光仪测试岩石矿物中硒元素试验研究

探讨了原子荧光仪测试岩石矿物中硒元素试验研究。运用原子荧光仪测试岩石矿物中硒元素,结果显示：原子荧光仪测试岩石矿物中方法硒元素的回收率、相对标准偏差、方法检出限分别为98.2%-103.0%、0.95%-5.80%、3.5×10^-11g/m L。原子荧光仪方法测试岩石矿物中硒元素具有较为快捷的速度、较高的灵敏度,且简便易行等,值得推广。     

铁硒共沉淀法去除原水中的硒

受微量硒污染的原水处理目前尚无现成的处理工艺或方法套用，为此考察了铁硒共沉淀法的除硒效果。结果表明，当原水硒浓度为50μg／L、FeCl3投量为5～80mg／L时，对硒的去除率为83．84％～98．39％，出水硒浓度为0．81～8．08μg／L，完全满足生活饮用水水质标准中对硒含量的规定。研究中还发现，FeCl3的除硒效果比FeSO4好。