Determination of free and protein-bound glutathione in HepG2 cells using capillary electrophoresis with laser-induced fluorescence detection

A rapid method using capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was developed to determine free and protein-bound glutathione (GSH) in human HepG2 hepatocarcinoma cells. The samples were derivatized with 5-iodoacetamidofluorescein (5-IAF), and analyzed at 22 kV using sodium phosphate buffer (10mM, pH 11.4) and an uncoated 58 cm x 75 microm I.D. fused silica capillary. The analysis time was less than 10 min and N-acetylcysteine was used as internal standard. The derivatization conditions, such as reaction time, 5-IAF concentration, running buffer and cartridge temperature were optimized. Argon gas was used in the study to prevent the oxidization of GSH during sample preparation. The optimized method required only 30-40 nl sample per analysis and was fast and sensitive. The method was applied to the analyses of HepG2 cells treated with the small metal chelating agent, pyrrolidine dithiocarbamate (PDTC). The results demonstrate that the amount of protein-bound GSH, which reflects the amount of protein S-glutathionylation, increased in a time-dependent manner upon cell treatment with PDTC, reaching a maximum of over 50% increase 2h post-PDTC.     

Sensitive and selective determination of glutathione in probiotic bacteria by capillary electrophoresis–laser induced fluorescence

Glutathione (GSH) is a thiol with an important function in protecting tissue against the oxidative stress which has been related to carcinogenesis in the colon. For this reason the development of probiotic species producing glutathione could be of great interest. To determine the glutathione content of some probiotic bacteria of the Bifidobacterium and Lactococcus genera, a very sensitive and selective analytical method based on capillary electrophoresis coupled to laser-induced fluorescence detection has been developed. Pretreatment of cell-lysate samples is very simple—precipitation of protein with acetonitrile in 1:2 volume ratio. The fluorophore 5-iodoacetamidofluorescein (5-IAF) was chosen for glutathione derivatisation; it reacts with thiols at pH 12.5, forming a fluorescent adduct which is excited by a laser at 488 nm for detection. The reaction conditions optimised were temperature, time, and 5-IAF/GSH molar ratio. Electrophoresis was performed with a carbonate buffer (25 mmol L⁻¹, pH 9.8) as background electrolyte and a voltage of 30 kV; an electrophoretic run was complete in less than 7 min. There was a good linear relationship between concentration and response in the range 2.5–500 ng mL⁻¹ and the LOD was 0.5 ng mL⁻¹. The glutathione content of probiotic cells was determined by using the standard additions method to reduce matrix effects. The method was fully validated and shown to be of suitable sensitivity and selectivity for determination of GSH in probiotic cell lysates.     

Thiol redox status evaluation in red blood cells by capillary electrophoresis-laser induced fluorescence detection

Thiols and in particular glutathione (GSH) play a central role in human metabolism, including the detoxification of xenobiotics, cell homeostasis, radioprotection, and antioxidant defence. Here, a new method is provided for the measurement of reduced and total forms of thiols in red blood cells. In order to minimize oxidation of reduced thiols, a water erythrocyte lysis (15 min at 4 degrees C) was performed followed by a protein precipitation step with acetonitrile. The supernatant was rapidly derivatized with 5-iodoacetoamidefluorescein that trapped thiol groups, thus minimizing auto-oxidation. Derivatized samples were separated in a 57 cm x 75 microm ID capillary by using 5 mmol/L sodium phosphate, 4 mmol/L boric acid as electrolyte solution with 75 mmol/L N-methyl-D-glucamine at pH 11.0. Under these conditions, cysteinylglycine (CysGly), cysteine (Cys), glutathione, and gamma-glutamylcysteine (GluCys) were baseline-resolved in approximately 4 min. Precision tests showed a good repeatability of our method both for migration times (coefficient of variation CV < 0.8%) and areas (CV < 3.3%). Furthermore, a good reproducibility of intrassay and interassay tests was obtained (CV < 5% and CV < 8%, respectively). The method was employed to investigate the effect of acidic precipitation on intracellular thiol concentration. Our data suggest that sample acidification causes a modification of the measured redox thiol status due to the development of a pro-oxidant environment; moreover, the thiol redox status of red blood cells was evaluated in 22 healthy volunteers.     

三角形法和四面体法优化选择毛细管区带电泳背景电解质

建立了两种高效、快速的毛细管区带电泳背景电解质(BGE)的优化方法三角形优化法和四面体优化法。以色谱指纹图谱指数F和色谱指纹图谱相对指数Fr作为评价毛细管电泳分析系统的目标函数,以雪莲药材水提取液为样品,考察一定浓度的硼砂、硼酸、磷酸氢二钠和磷酸二氢钠溶液按三角形优化法和四面体优化法构成背景电解质时对样品的分离情况,通过添加有机改性剂和调节pH进行再优化。用三角形法优化出以50 mmol/L硼砂-含3%乙腈的150 mmol/L磷酸二氢钠(体积比为1∶1)作为BGE时分离效果最佳,用四面体法优化出以50 mmol/L硼砂-150 mmol/L磷酸二氢钠-200 mmol/L硼酸(体积比为1∶1∶2,用0.1 mol/L氢氧化钠调pH 8.55)作为BGE时分离效果最佳,分别获得28个和25个电泳峰。所建立的方法操作简捷,适用于中药材水提取液或醇提取液的毛细管区带电泳BGE的选择。     

毛细管电泳-激光诱导荧光法测定细胞中谷胱甘肽

谷胱甘肽(GSH)在抵抗氧化应激和重金属解毒过程中发挥着重要作用,建立灵敏、准确的GSH定量分析方法对于研究细胞重金属毒性机制具有深远意义。该研究以肝癌细胞(HepG2)为研究对象,以活性基团为芳香邻二醛的2,3-萘二甲醛(NDA)为标记试剂,建立了一种高灵敏度的测定细胞中GSH含量的毛细管电泳-激光诱导荧光检测方法(CE-LIF)。实验考察了缓冲溶液的种类、pH、添加剂等对GSH与NDA的反应速率和NDA-GSH检测灵敏度的影响。比较了pH为7.4和9.2的三羟甲基氨基甲烷(Tris)缓冲溶液、pH为9.2的硼砂和Tris缓冲溶液中NDA-GSH的灵敏度和反应速率,结果显示在pH为9.2的硼砂缓冲溶液中NDA-GSH的灵敏度最高且反应速率最快。进一步比较了4种添加剂对NDA-GSH灵敏度的影响,结果显示以β-环糊精(β-CD)作为添加剂效果最好。在最优的实验条件下,GSH与NDA可以在5 min内达到反应平衡,3 min内检测到NDA-GSH电泳信号。采用外标法对细胞中的GSH进行定量分析,方法线性范围为0.01～20.00 mmol/L, GSH的检出限和定量限分别为0.006μm...     

Capillary electrophoresis with laser-induced fluorescence detection for ATP quantification in spermatozoa and oocytes

We describe a new capillary electrophoresis laser-induced fluorescence (CE-LIF) method for the quantification of adenosine 5′-triphosphate (ATP) in spermatozoa and oocytes. The optimization of the precapillary derivatization reaction between ATP and 4,4-difluoro-5,7-dimethyl-4-bora-3a,4adiaza-s-indacene-3-propionyl ethylene diamine hydrochloride (BODIPY FL EDA) has been described. BODIPY-ATP conjugate was analysed in an uncoated fused silica capillary of 75 μm ID and 50 cm effective length using a 10 mmol/L tribasic sodium phosphate buffer, pH 11.5, at 22 kV in <5 min. A good reproducibility of intra- and inter-assay tests was obtained (CV?=?4.55% and 7.14%, respectively). With respect to our previous CE-UV assay, the new method showed an improvement in sensitivity that was about 120-fold (limit of quantification, 0.15 vs 18 μmol/L). Method applicability was proven on the reproductive cells of several animal species (roosters, horses, sheep and goats). Due to the elevated sensitivity, the new assay allows the measurement of adenosine 5′-triphosphate levels from just 20 oocytes. Considering that ATP concentration in reproductive cells is related to the mitochondrial integrity after cryopreservation, the proposed method could be a useful tool in assisted reproductive technologies.     

Separation and determination of four active anthraquinones in Chinese herbal preparations by flow injection-capillary electrophoresis

A simple, rapid, and accurate method for the separation and determination of physcion, chrysophanol, aloe-emodin, and emodin in Rhubarb, Juemingzi, and Chinese herbal preparations was developed by combination of flow injection-capillary zone electrophoresis for the first time. The analysis was carried out using an unmodified fused-silica capillary (75 mm x 50 microm ID x 375 microm OD, effective separation length of 48 mm) and direct ultraviolet detection at 254 nm. By a series of optimization, the sample solvent consisted of NaOH (100 mmol/L) and ACN (1:1 v/v), and a running buffer composed of 15 mmol/L sodium borate - 12.5 mmol/L sodium dihydrogen phosphate - 42% v/v ACN (pH 10.1) was applied for the separation of the four anthraquinones. The separation was rapid and highly reproducible, with complete resolution of all four compounds within 6 min. The sample throughput rate could reach up to 12 per h. The repeatability (defined as relative standard deviation) was 4.45, 4.44, 4.34, 0.61% with peak height evaluation and 1.62, 0.89, 2.49, 2.19% with peak area evaluation for physcion, chrysophanol, aloe-emodin, and emodin, respectively.     

胶束电动毛细管色谱法分析头孢哌酮与其S-异构体等杂质

以十二烷基硫酸钠(SDS)胶束为准固定相,考察了头孢哌酮、头孢哌酮S-异构体、头孢哌酮杂质A及其他未知杂质在胶束电动毛细管色谱(MECC)分离模式下的分离行为。研究了运行缓冲液的pH值、磷酸盐浓度、SDS浓度、甲醇体积分数、分离电压、分离温度等因素对头孢哌酮、S-异构体、头孢哌酮杂质A及其他杂质的迁移时间、分离度以及可分离出的杂质个数的影响。结果发现,这些因素对头孢哌酮与诸杂质间的分离及检测有显著的影响,尤以pH值为最。它不仅影响它们的迁移时间和分离效率,还直接影响头孢哌酮及其杂质峰的检测。优化后的分离条件:运行缓冲液为70 mmol/L磷酸盐-100 mmol/L SDS (pH 6.5),分离电压为15 kV,分离温度为25 ℃。在此条件下,用非涂渍石英毛细管51.0 cm×75 μm(有效长度42.5 cm),压力进样5 kPa×5 s,在254 nm波长下进行检测,可分离出28个杂质,诸杂质彼此间及与头孢哌酮间可得到有效分离。并将该方法成功地用于测定注射用头孢哌酮钠的含量和有关物质,结果令人满意。     

超高效液相色谱-串联质谱法同时测定血清中12种抗癫痫药物

建立了超高效液相色谱-串联质谱同时测定血清中加巴喷丁、拉莫三嗪、普瑞巴林、拉考沙胺、左乙拉西坦、托吡酯、奥卡西平、氯硝西泮、丙戊酸钠、卡马西平、苯巴比妥、苯妥英钠12种抗癫痫药物的方法。将非那西丁和氯唑沙宗分别作为正离子和负离子模式下的内标物，血清经乙腈沉淀蛋白质后，取上清液进样分析。采用ACQUITY UPLC BEH C₁₈柱分离，流动相为水和甲醇（均含10 mmol/L甲酸铵），流速为0.4 mL/min。采用电喷雾电离源，在多反应监测和正、负离子模式下分段进行扫描分析。结果表明，12种抗癫痫药物在各自范围内线性关系良好，相关系数均大于0.992，在3个添加水平下方法的加标回收率为90.80%~114.0%，批内精密度RSD≤13.2%，批间精密度RSD≤14.8%。该方法专属性强，灵敏度高，可用于12种抗癫痫药物临床血药浓度监测及药代动力学研究。     

金纳米粒子富集-高效液相色谱同时测定人血浆中三种氨基硫醇

建立了金纳米粒子富集-高效液相色谱-紫外检测(HPLC-UVD)同时测定人血浆中3种氨基硫醇(半胱氨酸(Cys)、高半胱氨酸(Hcys)、谷胱甘肽(GSH))的新方法。以Tween 20修饰的金纳米粒子作为选择探针萃取富集氨基硫醇。经二硫苏糖醇脱附后,采用SpursilTM C18柱(250 mm×4.6 mm, 5 μm)分离氨基硫醇,以60 mmol/L磷酸盐缓冲溶液(pH 2.0)等度洗脱,检测波长为200 nm。3种氨基硫醇的浓度分别在0.025～350 μmol/L、0.02～60 μmol/L、0.01～50 μmol/L内与峰面积具有良好的线性关系,相关系数均高于0.99。方法检出限(信噪比为3)分别为5.0、6.0和2.5 nmol/L,回收率为92.8%～106.0%。该方法能显著降低血浆样品中内源性物质的干扰,提高HPLC-UVD的选择性和灵敏度。将该方法应用于心血管病人血浆中上述氨基硫醇的分离测定,结果显示: 与对照组相比,疾病组血浆中的Hcys和GSH水平存在显著性差异,Cys不存在显著性差异。     

毛细管区带电泳-间接紫外检测法快速测定食品中乳糖、蔗糖、葡萄糖和果糖

建立了毛细管区带电泳-间接紫外检测快速测定食品中乳糖、蔗糖、葡萄糖和果糖的方法。以水或5 mmol/L醋酸为样品提取液,未涂层熔融石英毛细管(30.2 cm(有效长度20 cm)×50 μm)为分离柱,4 mmol/L山梨酸钾+10 mmol/L磷酸钠+30 mmol/L NaOH(pH 12.56)+0.5 mmol/L十六烷基三甲基溴化铵(CTAB)为分离缓冲液,在-8 kV下分离,于254 nm波长下检测,10 min内实现了食品中上述4种糖的同时分离与测定。乳糖、蔗糖、葡萄糖和果糖的检出限(S/N=3)分别为50、75、25和25 mg/L,定量限(S/N=10)分别为150、225、75和75 mg/L,回收率在87.0%~107.0%之间,相对标准偏差在1.2%~4.7%之间。整个实验过程未使用有机溶剂。用该法测定了9种食品样品及1个质控样品,结果表明该法简单、快速、准确,适用于食品中乳糖、蔗糖、葡萄糖和果糖的日常测定。     

毛细管胶束电动色谱法测定夏枯草中两种有效成分

建立了毛细管胶束电动色谱法（ＭＥＫＣ）同时分离和测定夏枯草中齐墩果酸和熊果酸异构体含量的新方法。以１５ｍｍｏｌ／Ｌ磷酸氢二钠（Ｎａ２ＨＰＯ４）、１５ｍｍｏｌ／Ｌ硼砂（Ｎａ２Ｂ４Ｏ７）、１０ｍｍｏｌ／Ｌ十二烷基硫酸钠（ＳＤＳ）、５％（Ｖ／Ｖ）乙醇的缓冲溶液作为运行电解质溶液,在２０ｍｉｎ实现了齐墩果酸和熊果酸的基线分离。同时也研究了ＳＤＳ浓度和有机溶剂（乙醇）浓度对待测物质分离的影响。研究了不同提取     

在线推扫富集-胶束电动毛细管色谱检测旋覆花素中和大鼠血浆中的旋覆花内酯

采用熔融石英毛细管,以含有50 mmol/L 十二烷基硫酸钠的50 mmol/L硼酸盐缓冲液为电极缓冲液,以10 mmol/L硼酸盐缓冲液为上样缓冲液,经过对分离条件的优化,成功地建立了胶束电动毛细管色谱结合在线sweeping(推扫)富集技术检测中性脂溶性物质旋覆花内酯(acetylbritannilactone,ABL)的实验方法。所建方法的批内、批间测定值的相对标准偏差均小于5%,灵敏度为0.005 g/L,回收率大于92%;被检测样品的含量与峰面积呈良好的线性关系,相关系数为0.9975。用所建立的方法检测了旋覆花素中ABL的含量及其在体内的动态变化,结果表明胶束电动毛细管色谱结合在线sweeping样品富集技术可显著提高检测的灵敏度。该方法具有操作简单、进样量小(nL级)、检测速度快等特点,弥补了毛细管电泳在测定痕量组分方面的不足。     

Analysis of Chlorogenic Acid in Herbal Medicines by Capillary Electrophoresis

Atpresent,thecommonlyusedmethodforanalyzingherbalmedicinesishighperformanceliquidchromatography(HPLC).However,theuseofHPLCisrestrictedformanyreasons.Themostseriousproblemisthatthechromatographiccolumniseasilycontaminated.ComparedwithHPLC,capillaryelectrophoresis(CE)ischaracterizedwithhighefficiency,rapidity,lowcostandmultiplemodestobechosen.Inaddition,thecapillarycanbeeasilyregenerated.SoCEisidealforanalyzing"dirty"samples,suchasChineseherbalmedicines.Infact,studiesintheareaarebecoming…     

两步柱色谱法分离纯化重组猪β2-肾上腺素能受体

β2-肾上腺素能受体是细胞表面受体的一种,它能通过偶联异源三聚体G蛋白将信号转导引入到细胞内部。本实验在成功克隆、表达β2-肾上腺素能受体的基础上,建立了一种两步柱色谱分离纯化目的蛋白质的方法。首先利用Ni2+螯合的高分辨纯化的预带电荷介质Sepharose High Performance与含有六聚组氨酸标签的蛋白质特异结合的性质,对目的蛋白质进行初步分离,接着运用快流速Q琼脂糖凝胶(Quaternary Sepharose Fast Flow)对其进行进一步的分离纯化。采用该方法得到的β2-肾上腺素能受体蛋白质经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和高效凝胶排阻色谱检测其纯度约为95%。结果表明该方法可以对重组猪β2-肾上腺素能受体进行有效的分离纯化。     

Determination of strychnine and brucine in traditional Chinese medicine preparations by capillary zone electrophoresis with micelle to solvent stacking

A novel micelle to solvent stacking on-line sample preconcentration technique in capillary zone electrophoresis（MSS-CZE） has been developed to determine the strychnine and brucine in traditional Chinese medicine preparations.The optimal running buffer was 30 mmol/L H₃PO₄ containing 20%acetonitrile at pH 4.0.The sample matrix was 8 mmol/L H₃PO₄ containing 5 mmol/L sodium dodecyl sulfate（SDS） at pH 3.0.The established MSS-CZE method afforded more than 50-fold improvements in concentration sensitivity compared with typical CZE-UV analysis.The calibration curve was linear in the range from 0.2 to 15.0μg/ mL for both strychnine and brucine,with correlation coefficients of 0.9984 and 0.9976,respectively.The limits of detection（5/ N = 3:1） for strychnine and brucine were 0.02 and 0.05μg/mL,respectively.The MSS-CZE method has been successfully applied to the analysis of strychnine and brucine in Chinese medicinal preparations.     

Determination of cellular redox status by stable isotope dilution liquid chromatography/mass spectrometry analysis of glutathione and glutathione disulfide

Oxidation of glutathione (GSH) to glutathione disulfide (GSSG) occurs during cellular oxidative stress. The redox potential of the 2GSH/GSSG couple, which is determined by the Nernst equation, provides a means to assess cellular redox status. It is difficult to accurately quantify GSH and GSSG due to the ease with which GSH is oxidized to GSSG during sample preparation. To overcome this problem, a stable isotope dilution liquid chromatography/multiple reaction monitoring mass spectrometry (LC/MRM-MS) method has been developed using 4-fluoro-7-sulfamoylbenzofurazan (ABD-F) derivatization. ABD-F derivatization of the GSH thiol group was rapid, quantitative, and occurred at room temperature. The LC/MRM-MS method, which requires no sample clean-up, was validated within the calibration ranges of 5 to 400 nmol/mL in cell lysates for GSH and 0.5 to 40 nmol/mL in cell lysates for GSSG. Calibration curves prepared by adding known concentrations of GSH and GSSG to cell lysates were parallel to the standard curve prepared in buffers. GSH and GSSG concentrations were determined in two monocyte/macrophage RAW 267.4 cell lines with or without 15-LOX-1 expression (R15LO and RMock cells, respectively) after treatment with the bifunctional electrophile 4-oxo-2(E)-nonenal (ONE). R15LO cells synthesized much higher concentrations of the lipid hydroperoxide, 15(S)-hydroperoxyeicosatetraenoic acid (15-HPETE), which undergoes homolytic decomposition to ONE. GSH was depleted by ONE treatment in both RMock and R15LO cells, leading to significant increases in their redox potentials. However, R15LO cells had higher GSH concentrations (most likely through increased GSH biosynthesis) and had increased resistance to ONE-mediated GSH depletion than RMock cells. Consequently, R15LO cells had lower reduction potentials at all concentrations of ONE. GSSG concentrations were higher in R15LO cells after ONE treatment when compared with the ONE-treated RMock cells. This suggests that increased expression of 15(S)-HPETE modulates the activity of cellular GSH reductases or the transporters involved in removal of GSSG.     

Stability and Determination of Metamizole Sodium by Capillary Electrophoresis Analysis Combined with Infra-red Spectroscopy

Metamizole sodium was chosen as a representative of unstable analytes for investigation by discussing the effects of oxygen and solvent on its degradation reaction using the capillary electrophoresis technique.A possible degradation mechanism was deduced from the observed behavior and was confirmed by infra-red spectroscopic study.The degradation reaction could be inhibited obviously by methanol instead of water as the solvent of analyte.Under the optimized conditions:separation voltage of 20 kV,and 5 mmol/L disodium hydrogen phosphate and 5 mmol/L borax with 10% methanol(pH 9.12)as the running buffer,the standard curve of metamizole sodium was linear in a range of 3.77—74.07 mg/L.A satisfactory result was achieved when the technique was used to detect metamizole sodium in tablet.     

功能化纳米金增强的谷胱苷肽电化学检测和巯基识别

以冠有大量二茂铁的纳米金微粒/抗生蛋白链菌素结合物为标记物,将其标记于生物素修饰的巯基识别试剂上,制成了具有电化学活性和纳米金放大作用的传感器.首先将双官能团的羟基琥珀酰亚胺酯自组装于电极表面上,借助两步交联反应固定含巯基的蛋白质,并且引入巯基识别试剂标记生物素的马来酰亚胺,随后利用生物素与链霉抗生物素之间的特异性吸附作用,引入功能化的纳米金.采用伏安法测定修饰在纳米金上的二茂铁,可识别和测定表面固定的蛋白质,还原型谷胱苷肽在5μmol/L～0.1mmol/L浓度范围内存在线性关系,检测限可达到1nmol/L.     

高效液相色谱法测定细胞内三磷酸腺苷及其代谢物的含量（英文）

研究了三磷酸腺苷(ATP)及其代谢物在细胞内的含量以及2-叔丁基-1,4-苯醌(TBBQ)对ATP及其代谢产物在细胞内含量的影响。建立了一种高效液相色谱法(HPLC)用于快速分离、检测细胞内ATP及其代谢产物(二磷酸腺苷(ADP)和一磷酸腺苷(AMP))的含量。使用岛津高效液相系统及艾杰尔Venusil MP C18柱,采用等度洗脱的方式。流动相A相为50 mmol/L磷酸氢二钠和15 mmol/L三甲胺(TEA),用醋酸(HAc)调节pH至7.88;流动相B相为甲醇。采用建立的高效液相色谱法得到了3种代谢物的工作曲线,相关系数高(R~2≥0.999 6),MRC-5细胞中3种代谢物的含量均在线性范围(0.1~100μmol/L)内。该方法检出限低。采用预冷的80%(体积分数)甲醇水溶液提取细胞内的代谢物。该研究建立的方法成功地应用于检测MRC-5细胞中的ATP、ADP和AMP的含量,结果表明,TBBQ会对ATP、ADP、AMP在细胞内的含量产生影响,但TBBQ浓度和ATP、ADP以及AMP在MRC-5细胞内浓度的关系比较复杂。