Gastric digestion of pea ferritin and modulation of its iron bioavailability by ascorbic and phytic acids in caco-2 cells

瞄准：在 caco-2 房间线模型理解版本和豌豆含铁听铁的肠的举起的消化稳定性和机制。方法：豌豆种子含铁锡用分别由胶化过滤层析跟随了的盐被净化。含铁听铁的简历可获得性当面用联合在试管内 digestion/Caco-2 房间模型被估计或抗坏血酸和 phytic 的缺席。Caco-2 房间含铁听形成被用作铁举起的一个代理人标记。在模仿的胃的 pH 下面的豌豆含铁锡的结构的变化用电气泳动，胶化过滤和圆形的二色性光谱学被描绘。结果：caco-2 房间含铁听形成显著地被增加(P 【 0.001 ) 与 FeSO4 (19.3 +/- 9.8 ng/mg 蛋白质) 并且豌豆含铁锡(13.9 +/- 6.19 ng/mg 蛋白质) 与空白的文摘相比(3.7 +/- 1.8 ng/mg 蛋白质) 。当 phytic 减少了时，提高的抗坏血酸豌豆含铁听铁简历可获得性。然而，也当面或抗坏血酸的缺席， caco-2 房间的含铁听内容是显著地有豌豆含铁锡的更少比与 FeSO4。在胃的 pH，相应于含铁锡的乐队都没在本国的页或 SDS 页上面对胃朊酶任何一个被观察。胶化过滤层析和圆形的二色性光谱学揭示了第四级、第二等的结构的 pH 依赖者损失。结论：在胃的条件下面，豌豆含铁锡的铁核心由于酸被释放进消化媒介蛋白质的导致的结构的改变和分离。释放的铁与导致豌豆含铁听铁简历可获得性的调整的饮食的因素交往，类似于 non-heme 铁的典型特征。

Nanosized SnO_2 Particles Dispersed on a Graphite Electrode for Selective Detection of Dopamine and Ascorbic Acid

A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peaks by 230 mV. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine and ascorbic acid can be determined simultaneously with the modified electrode. The electrode shows good sensitivity, selectivity and stability.

Ascorbic acid induces Ca2+-dependent necrosis mediated by reactive oxygen species in colorectal cancer cells

OBJECTIVE Ascorbic acid(AA),commonly known as vitamin C,is a small molecular widely distributed in in food and traditional herbs.Recently,there are some literatures reported that high concentration AA could selectively kill the cancer cells but not the normal cells.This study was designed to explore the underlying mechanisms.METHODS Colorectal cancer line cells were cultured and treated with AA.The cytotoxic,intracellular ATP level,reactive oxygen species,calcium,were determined with commercial kits and fluorescent probes.RESULTS High concentration of AA induced cell death in HCT116 and HT29 colorectal cancer cells in concentration-and time-dependent manner.AA treat⁃ment induced ATP decrease,LDH release,cell swollen and loss of plasma membrane integrity.Pharmacological inhibi⁃tors for apoptosis,necroptosis,autophagy,pyroptosis and oncosis showed no effect on AA-induced cell death.Further⁃more,ROS level increase and intracellular calcium(Ca2+)accumulation were observed after AA treatment.ROS scavenger N-acetyl cysteine(NAC),intracellular calcium chelator BAPTA-AM and intracellular calcium inhibitor 2-aminoethoxy⁃diphenyl borate(2-APB)could attenuate the cell death induced by AA.NAC could attenuate both ROS increase and intracellular Ca2+accumulation induced by AA,while BAPTA-AM could only attenuate intracellular Ca2+accumulation.In addition,high concentration AA induced mitochondrial damage and mitochondrial ROS generation.CONCLUSION AA induces Ca2+-dependent programed necrosis mediated by ROS.Our study provided new insights into high concentration AA induced cell death in human colon cancer cells.

Cu^(2+)-Catalyzed Oscillatory Oxidation of Ascorbic Acid by O_2 Flow

A novel heterogeneous oscillator, the Cu2+-catalyzed oscillatory oxidation of ascorbic acid (Vitamin C) in aqueous solution by O-2 flow was reported. Both the potential oscillations on Pt-electrode corresponding to [Cu2+] and the absorbance oscillations at lambda =260 nm corresponding to [ascorbic acid] were observed. Oscillations in the completely homogeneous system were also observed. Effects of several factors on the oscillations were investigated.

An improved sensitivity non-enzymatic ascorbic acid sensor based on a Ag_2O nanowire modified Ag electrode

In this paper, the Ag2O nanowires had been prepared and applied for the fabrication of ascorbic acid sensors with high enhanced sensitivity by using self-assembly technology. The structures and morphologies of Ag2O nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The direct electrocatalytic oxidation of ascorbic acid in alkaline medium at Ag2O nanowires modified electrodes had been investigated in detail and the condition for determination of ascorbic acid was optimized, such as support-electrolyte, pH and scan speed. The oxidation peak current changed linearly with the concentration of ascorbic acid over the range from 2.0×10-8 mol/L to 1.0 mmol/L, and the detection limit can reach 1.0×10-8mol/L. Compared to a bare Ag electrode, a substantial decrease in the overvoltage of the ascorbic acid oxidation was observed at the Ag nanowires electrodes with oxidation starting at ca. 0.7V vs. Ag/AgCl (saturated KCl). The Ag2O nanowires modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of ascorbic acid, thus is promising for the future development of non-enzymatic ascorbic acid sensors.

Long-term culture of primary porcine mature hepatocytes in the medium supplemented with ascorbic acid 2-phosphate

In this study, the effect of ascorbic acid 2-phosphate (Asc2P) was tested on porcine and rat mature hepatocytes in vitro. a). Asc2P increased the porcine, but not rat, albumin secretion and mRNA expression. The enhancing effect of Asc2P on porcine C/EBP alpha mRNA was observed in porcine mature hepatocytes. These data suggested that Asc2P played an important role in the regulation of porcine albumin mRNA level. b). The enhancing effect of Asc2P on ammonium metabolic activity was also observed in porcine, but not rat, mature hepatocytes. The porcine ornithine transcarbamylase (OTC) and arginase mRNAs were augmented by Asc2P, indicating that Asc2P had a direct effect on the urea cycle. c). The porcine collagen type I and type III mRNA, but not type XII mRNA, were detected as well, sugessting that Asc2P did not have the effect on the non-parenchymal hepatocytes to induce collagen type I and III mRNA expression. d). Our RT-PCR analysis demonstrated that the porcine hepatocytes expressed the sodium-ascorbate co-transporters SVCT1 and SVCT2, however, the intensities of porcine sodium-ascorbate co-transporters SVCT1 and SVCT2 bands were not changed markedly. These findings indicated that the Asc2P had no effect on SVCT1 and SVCT2 mRNA expression. e). The enhancing effect of Asc2P on porcine albumin mRNA was inhibited by staurosporine, a portein kinase inhibitor. We conclude that the enhanced albumin mRNA by Asc2P might be due to activation of tyrosine protein kinase and/or PKC and the Asc2P enhanced porcine albumin mRNA mainly at the transcriptional step.

2-O-α-D-葡萄糖基-L-抗坏血酸的酶法合成及其应用研究进展

2-O-α-D-葡萄糖基-L-抗坏血酸(2-O-D-glucopyranosyl-L-ascorbic acid,AA-2G)不仅稳定性强且保留了L-抗坏血酸(L-ascorbic acid,L-AA)的大部分生理活性,是L-AA最好的替代品。体外酶法合成AA-2G具有经济、快速、绿色和安全等显著优势,是规模化生产AA-2G的可行方法。该文综述体外酶法合成AA-2G的研究进展,重点梳理环糊精糖基转移酶和蔗糖磷酸化酶合成AA-2G的研究现状,并对AA-2G的功能及应用前景进行讨论和展望。

Role of dissolved oxygen reduction in improvement inhibition performance of ascorbic acid during copper corrosion in 0.50 mol/L sulphuric acid

The kinetics of dissolved O_2 reduction and hydrogen evolution reactions on copper surface was studied in naturally aerated and air and O_2-saturated 0.50 mol/L H_2SO_4 solutions using polarization measurements combined with the rotating disc electrode (RDE).The Koutecky-Levich plot indicated that the dissolved O_2 reduction at the copper electrode was an apparent four-electron process.A correlation between the presence of dissolved O_2 and the formation of Cu_2O,confirmed from XRD,was discussed. Ascorbic a...

高效液相色谱法测定食品中的抗坏血酸2-葡萄糖苷

建立了高效液相色谱法测定食品中维生素C衍生物抗坏血酸2-葡萄糖苷含量的方法。试样经偏磷酸溶解超声提取后,经Zorbax SB-C_(18)(4.6 mm×250 mm,5μm)色谱柱分离,高效液相色谱紫外检测器检测,根据保留时间定性,用外标法定量。结果显示,该方法的线性关系良好,线性相关系数为1.000,方法精密度为0.032%(n=6),重复性为0.023%(n=6),回收率在97.2%~98.6%,相对标准偏差≤2.13%(n=6)。该方法前处理简单,回收率高,重复性好,适用于食品中抗坏血酸2-葡萄糖苷的测定。

Effects of exogenous salicylic acid on growth and H_2O_2-metabolizing enzymes in rice seedlings under lead stress

Salicylic acid （SA） was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H2O2-metabolizing enzymes in rice seedlings under lead stress were studied. When rice seedlings grown in nutrient solution containing Pb^2＋ （0, 0.05, 0.15, 0.25 mmol/L） for 18 d, the plant biomass as well as the chlorophyll content of leaves decreased with increasing Pb concentration. The pre-treatment with SA （treated with 0.1 mmol/L SA for 48 h before Pb stress） partially protected seedlings from Pb toxicity. The chlorophyll contents were significant higher in leaves of Pb-exposed with SA pre-treatment seedlings than in Pb-exposed plants at the same Pb intensity. SA pre-treated alone could significantly increase the length of shoot and root of seedlings but the vigour difference was not marked under long-term exposure to Pb toxicity. SA pre-treated influence the H2O2 level in leaves of seedlings by up-regulating the activity of superoxide dismutase （SOD）, repressing the activity of catalase （CAT） and ascorbate peroxidase （APX） depending on the concentrations of Pb^2＋ in the growth medium. The results supported the conclusion that SA played a positive role in rice seedlings against Pb toxicity.

Electrochemical determination of vitamin C in the presence of uric acid by a novel TiO_2 nanoparticles modified carbon paste electrode

The electrochemical behavior of vitamin C（ascorbic acid or AA） is investigated on the surface of a carbon-paste electrode modified with TiO2 nanoparticles and 2,2＇-（1,2 butanediylbis（nitriloethylidyne））-bis-hydroquinone（BBNBH）.The prepared modified electrode showed an efficient catalytic role in the electrochemical oxidation of AA,leading to remarkable decrease in oxidation overpotential and enhancement of the kinetics of the electrode reaction.This modified electrode exhibits well-separated oxidation peaks for AA and uric acid（UA）.The modified electrode is successfully applied for the accurate determination of AA in pharmaceutical preparations.

环糊精葡萄糖基转移酶合成AA-2G反应条件初探

为了探究重组菌株pET-28a(+)-cgt-T1/BL21(DE3)产生的环糊精葡萄糖基转移酶(Cyclodextrin glucosyltransferase,CGTase)催化合成2-O-α-D-吡喃葡萄糖基-L-抗坏血酸(Ascorbic acid 2-glucoside,AA-2G)的效果,用LB发酵培养基表达重组蛋白CGTase-T1,经亲和纯化柱纯化并浓缩后,测定其β-环化活性和歧化活性。以维生素C(Vitamin C,V_(C))和β-环糊精为底物,酶法合成AA-2G,并通过单因素优化实验,进一步探究了不同糖基供体、底物浓度、pH、温度、底物比例、蛋白浓度以及反应时间对AA-2G产量的影响,对酶合成AA-2G的动力学进行了分析。结果表明:此酶具有合成AA-2G的能力,未优化前AA-2G的产量为0.67 g/L。优化后,考虑到低成本和经济效益,选择可溶性淀粉和麦芽糊精为糖基供体,当糖基供体为可溶性淀粉时,底物浓度为70 g/L,反应pH4.5,反应温度37℃,底物比例3/3(VC/糖基供体),蛋白浓度5.0 mg/mL,反应时间为42 h时,该重组CGTase催化合成AA-2G的产量最高能达到12.68 g/L;当糖基供体为麦芽糊精时,底物浓度为30 g/L,反应pH5.0,反应温度37℃,底物比例4/2,蛋白浓度5.0 mg/mL,反应时间为30 h时,该重组CGTase催化合成AA-2G的产量最高能达到4.96 g/L。在最适条件下,AA-2G的产量分别是未优化反应条件下的18.93倍和7.40倍。经动力学分析发现可溶性淀粉作为糖基供体的催化效率高于麦芽糊精,因此,可溶性淀粉作为糖基供体比麦芽糊精更具有优势,合成得到AA-2G的产量更高。本研究成功将重组CGTase-T1用于AA-2G的合成,通过优化酶法合成的反应条件,使AA-2G的产量得到了大幅提高,为实现AA-2G的工业生产提供参考意义。

Electrosynthesis, Characterization and Electrocatalytic Behaviour of Organic-Metal Thin-Films Based on 2,2’-Bithiophene-5-carboxylic Acid and Metal Ions

2,2’-Bithiophene-5-carboxylic acid (BTA) thin-films on platinum (Pt) electrodes were electrochemically prepared in acetonitrile solution containing 0.1 M tetrabutylammonium perchlorate (TBAP) and 0.05 M BTA. These films were complexes with several metal ions such as Cu2+, Ag+ and Co2+. Their structural characteristics were compared with those of powder complexes chemically prepared from BTA and the corresponding metal ion. IR and XPS techniques reveal that the film complexes with metal ions have the same structures as the corresponding powder complexes. The electrocatalytic activity of BTA film-metal ions has been investigated toward ascorbic acid (AA) oxidation and compared to that obtained on a free BTA film. BTA film-metal ions exhibit good catalytic proprieties and better detection of AA than a free BTA film. This new propriety allows these films to be used as electrochemical sensors. This electronic document is a “live” template. The various components of your paper [title, text, heads, etc.] are already defined on the style sheet, as illustrated by the portions given in this document.

Enhanced Iontophoretic Delivery of Magnesium Ascorbyl 2-Phosphate and Sodium Fluorescein to Hairless and Hairy Mouse Skin

We recently reported that L-ascorbic acid 2-phosphate (AP) stimulates the growth of human dermal papilla (DP) cells, induces secretion of IGF-1 from the DP cells to promote hair shafts elongation in cultured human hair follicles, and triggers early progression from the telogen to anagen phase in mice. Since the magnesium salt of AP (APMg) is a highly hydrophilic ionic molecule, it is not easy to deliver this reagent to the skin or hair follicles by topical application alone. In order to enhance skin penetration of APMg without changing any molecular properties, a non-invasive iontophoretic delivery method was introduced. Iontophoresis of the negatively charged APMg under the electrode bearing same charge (cathode) significantly enhanced the in vitro penetration of APMg into a Franz cell equipped with mouse dorsal skin. In contrast, iontophoretic movement with the anode inhibited APMg penetration achieved with passive diffusion alone. The effect of iontophoresis on enhancing the penetration of APMg was also found to be much higher in the skin of hairy mice (3 - 8 times) compared to hairless mice (1.5 - 2.5 times). These findings indicated that iontophoretic movement induced the transfollicular pathway more strongly and effectively than the transdermal pathway. This phenomena was also demonstrated by the in vivo iontophoretic delivery of sodium fluorescein using hairy and hairless mice. The degree of iontophoretic enhancement during APMg penetration was also dependent on various conditions such as current density and application duration.

外源ASA、H_(2)O_(2)对牡丹切花衰老过程中生理活性及细胞学特性的影响

为解析外源ASA、H_(2)O_(2)作用下牡丹切花衰老的细胞学和生理学机制,本试验以‘凤丹’切花为材料,研究施加不同浓度ASA、H_(2)O_(2)对‘凤丹’瓶插切花花瓣生理指标和细胞核形态的影响。结果表明:外源ASA和H_(2)O_(2)处理下,切花SOD活性受到抑制,高浓度处理激发了POD活性,CAT活性受到明显影响且整体变化趋向于平缓,MDA含量明显下降。5 mg/L ASA和0.03 mg/L H_(2)O_(2)处理,能有效维持切花细胞活性氧清除系统的平衡,减轻活性氧对细胞膜的破坏作用;细胞核完整率较高,瓶插末期仍然维持大部分细胞核规则、明亮,能有效缓解‘凤丹’切花的细胞程序性死亡,也即能延缓切花衰老,有较好的保鲜效果。该研究可为进一步揭示外源H_(2)O_(2)、ASA对牡丹切花保鲜时间的延长提供试验和理论依据。

2-氨基吡啶修饰电极的电化学性质及对抗坏血酸的测定

研究了２－氨基吡啶聚合膜修饰玻碳电极的制备及其电化学性质，并用于抗坏血酸（ＡＡ）的测定。在ｐＨ５．７ＢＲ缓冲溶液中，ＡＡ在 ２－氨基吡啶修饰电极上产生一灵敏的氧化峰，峰电流与ＡＡ浓度在４ × １０－６～１０－３ｍｏｌ／Ｌ范围内呈良好的线性关系，检测下限为 １．３ × １０－６ｍｏｌ／Ｌ。该电极对 ＡＡ有增敏作用，对多巴胺（ＤＡ）有排斥作用，重现性良好，可用于ＡＡ的测定。

2-酮-L-古龙酸还原酶分离纯化及其理化、酶学性质的研究

从发酵Ｌ山梨糖的Ｇｌｕｃｏｎｏｂａｃｔｅｒｏｘｙｄａｎｓ和Ｂａｃｉｌｕｓｍｅｇａｔｅｒｉｕｍ２９８０混和菌株的无细胞抽提液中分离到了２酮Ｌ古龙酸还原酶（ＫＧＲ），测得其分子量为９０ｋＤａ。动力学性质研究表明它为一个典型的ＭｉｃｈａｅｌｉｓＭｅｎｔｅｎ氏酶，对２酮Ｌ古龙酸作用的Ｋｍ值为３４２×１０－３ｍｏｌ，最适作用ｐＨ为６５，最适作用温度为３０℃。２酮Ｌ古龙酸还原酶的合成不受Ｌ山梨糖和２酮Ｌ古龙酸的诱导，故推测２酮Ｌ古龙酸还原酶是Ｇｌｕｃｏｎｏｂａｃｔｅｒｏｘｙｄａｎｓ的一个组成酶。

L-抗坏血酸-2-磷酸酯镁的合成

以Ｌ抗坏血酸为基本原料合成Ｌ抗坏血酸２磷酸酯镁。对两种合成方法直接酰化法和基团保护法作实验比较和改进。直接酰化法中，采用混合碱（ 包括氧化镁） 可使磷酰化与成盐反应合并为一步进行，并能提高产率，而采用基团保护法能取得最佳的合成效果。

用体外消化／Caco-2细胞模型观察维生素C和柠檬酸对铁生物利用的影响

目的采用体外消化/Caco-2细胞模型来观察维生素C和柠檬酸对铁生物利用的影响,并验证在本实验室建立的体外消化/Caco-2细胞模型的有效性。方法利用一个带透析膜的插入环将体外消化和Caco-2细胞培养结合在一起,模拟体内环境,使食物的消化和吸收在该模型中能同时进行。并在含铁样品液中分别加入维生素C和柠檬酸,以Caco-2细胞的铁蛋白形成量作为反映铁生物利用率的指标。结果在样品液铁浓度<100μmol/L时,细胞中铁蛋白形成量随着铁浓度的增加而递增;加维生素C组的细胞铁蛋白形成量高于加柠檬酸组;加入维生素C使方法更灵敏,加入柠檬酸使测定的铁浓度范围更宽。结论在本实验室建立的体外消化/Caco-2细胞模型是成功的,维生素C对铁生物利用的促进作用高于柠檬酸。