反相高效液相色谱法分析人体胆汁中结合型胆汁酸

根据反相液相色谱的保留值方程ＩｇＫ＇＝ａ＋ｃ．ｃｂ,结合型胆２汁酸的选择性变化规律ｌｇａ＝△ａ＋△ｃｖ．ｃｂ及结合型胆汁酸的标准样品色谱保留值,对人体胆汁中６种结合型胆汁酸进行了定性定量分析。６种结合型胆汁酸的浓度在０～１０．１５ｇ／Ｌ范围２内与相应的色谱峰高成良好的线性关系（相关系数在０．９９９６～０．９９７９之间）。     

反相液相色谱结合型胆汁酸的选择性变化规律

本文报道了反相液相色谱(RP-HPLC)和离子对反相液相色谱甘氨型(G)和牛磺型(T)结合胆汁酸的选择性变化规律,首次发现在给定冲洗剂浓度下,G、T对结合型胆汁酸的选择性因子或结合型选择性为常数。本文同时还在反相液相色谱保留值基本方程的基础上讨论了G、T对选择性变化规律的理论依据。     

反相高效液相色谱法测定鼠胆汁中游离与结合型胆汁酸

建立了一种柱前衍生反相高效液相色谱荧光检测大鼠胆汁中游离与结合型胆汁酸的方法.以4-溴甲基-7-甲氧基香豆素为衍生剂,月桂酸为內标,Waters Nova C18色谱柱分离,采用甲醇/乙腈和水梯度洗脱,荧光激发波长(λex)330 nm,发射波长(λem)400 nm,內标标准曲线法定量.各胆汁酸在5-2 400μmol/L范围内线性良好,r为0.998 9-0.999 7.最低检出限为1.2-2.5μmol/L.精密度日内在1.05%-3.67%之间,日间在3.16%-6.83%之间.平均回收率为87.8%-106.7%.该方法灵敏、重复性好,分析时间短,线性范围宽,适合于科研工作中对鼠胆汁中各胆汁酸进行定量检测.     

Isomaltulose Exhibits Prebiotic Activity,and Modulates Gut Microbiota,the Production of Short Chain Fatty Acids,and Secondary Bile Acids in Rats

In vitro experiments have indicated prebiotic activity of isomaltulose, which stimulates the growth of probiotics and the production of short chain fatty acids (SCFAs). However, the absence of in vivo trials undermines these results. This study aims to investigate the effect of isomaltulose on composition and functionality of gut microbiota in rats. Twelve Sprague–Dawley rats were divided into two groups: the IsoMTL group was given free access to water containing 10% isomaltulose (w/w), and the control group was treated with normal water for five weeks. Moreover, 16S rRNA sequencing showed that ingestion of isomaltulose increased the abundances of beneficial microbiota, such as Faecalibacterium and Phascolarctobacterium, and decreased levels of pathogens, including Shuttleworthia. Bacterial functional prediction showed that isomaltulose affected gut microbial functionalities, including secondary bile acid biosynthesis. Targeted metabolomics demonstrated that isomaltulose supplementation enhanced cholic acid concentration, and reduced levels of lithocholic acid, deoxycholic acid, dehydrocholic acid, and hyodeoxycholic acid. Moreover, the concentrations of propionate and butyrate were elevated in the rats administered with isomaltulose. This work suggests that isomaltulose modulates gut microbiota and the production of SCFAs and secondary bile acids in rats, which provides a scientific basis on the use of isomaltulose as a prebiotic.     

基于胆汁酸的刺激响应聚合物

刺激响应聚合物是当今材料科学研究的热点之一。其在外界刺激下,自身的物理或者化学性质发生变化产生响应,在药物可控释放、生物传感器、催化、吸附分离等方面有广阔的应用。胆汁酸是天然的甾类生物分子,其分子结构中含有羟基和羧基等官能团,容易进行化学修饰,且具有双亲性和一定的刚性。在聚合物中引入胆汁酸分子,能够从结构和功能两个方面丰富刺激响应高分子的研究。一方面,胆汁酸及修饰的胆汁酸既可以作为单体直接聚合,也可以被连接到含有一定官能团的聚合物上,由此可以得到以胆汁酸作为主链、侧基、端基,以及胆汁酸作为星形聚合物的核等多种聚合物结构。另一方面,胆汁酸的引入不仅可以提高聚合物的生物相容性,有效地赋予聚合物胆汁酸结构的独特性质,而且可以用于构建具有一定刺激响应功能的组装结构,进而应用于形状记忆、手性分离、药物载体等材料中。本文综述了基于胆汁酸的刺激响应聚合物近年来的相关工作,从基于胆汁酸的刺激响应聚合物的分子设计和结构构筑出发,结合其性质和应用进行论述,也对该领域的改进和发展提出展望。     

Bile Acids: Physiological Activity and Perspectives of Using in Clinical and Laboratory Diagnostics

Bile acids play a significant role in the digestion of nutrients. In addition, bile acids perform a signaling function through their blood-circulating fraction. They regulate the activity of nuclear and membrane receptors, located in many tissues. The gut microbiota is an important factor influencing the effects of bile acids via enzymatic modification. Depending on the rate of healthy and pathogenic microbiota, a number of bile acids may support lipid and glucose homeostasis as well as shift to more toxic compounds participating in many pathological conditions. Thus, bile acids can be possible biomarkers of human pathology. However, the chemical structure of bile acids is similar and their analysis requires sensitive and specific methods of analysis. In this review, we provide information on the chemical structure and the biosynthesis of bile acids, their regulation, and their physiological role. In addition, the review describes the involvement of bile acids in various diseases of the digestive system, the approaches and challenges in the analysis of bile acids, and the prospects of their use in omics technologies.     

Microdetermination of Bile Acids by High-Performance Liquid Chromatography Equipped with a High Sensitive Conductance Detector

Abstract

Conductimetric detection of bile acids in reversed phase high-performance liquid chromatography is described. The solvent system of the mixture of water and organic solvent containing small amount of basic salts such as ammonium carbonate is found useable by removing the cation with the cation exchange column inserted between the ODS column and the conductance detector. Thus, a few ng of tauro-and glyco-conjugated bile acids can be detected without tedious derivatization and hydrolysis.     

Structural and Functional Implications of the Interaction between Macrolide Antibiotics and Bile Acids

Macrolide antibiotics, such as azithromycin and erythromycin, are in widespread use for the treatment of bacterial infections. Macrolides are taken up and excreted mainly by bile. Additionally, they have been implicated in biliary system diseases and to modify the excretion of other drugs through bile. Despite mounting evidence for the interplay between macrolide antibiotics and bile acids, the molecular details of this interaction remain unknown. Herein, we show by NMR measurements that macrolides directly bind to bile acid micelles. The topology of this interaction has been determined by solvent paramagnetic relaxation enhancements (solvent PREs). The macrolides were found to be bound close to the surface of the micelle. Increasing hydrophobicity of both the macrolide and the bile acid strengthen this interaction. Both bile acid and macrolide molecules show similar solvent PREs across their whole structures, indicating that there are no preferred orientations of them in the bile micelle aggregates. The binding to bile aggregates does not impede macrolide antibiotics from targeting bacteria. In fact, the toxicity of azithromycin towards enterotoxic E. coli (ETEC) is even slightly increased in the presence of bile, as was shown by effective concentration (EC₅₀) values.     

Liquid Chromatographic Analysis of Bile Acid Methyl Esters

Abstract

Methods have been developed for the qualitative and quantitative analysis of hydroxy and keto derivatives of methyl cholanates utilizing a ¼″ by 1′ μPorasil column, various mixtures of hexane and ethyl acetate and a refractive index detector. The system has been calibrated for some of the methyl dihydroxycholanates using 3α;,7α-dihydroxy-12-oxocholanate as an internal standard and applied to the analysis of the mixtures of diols resulting from the reduction of methyl 3,12-dioxocholanate with NaBH₄ and with Raney nickel.     

胆甾酸缀合物的生物及生理学功能

本文综述近几年来胆甾酸缀合物的生物及生理学功能研究概况。主要包括胆甾酸天然缀合物模拟的化学合成,新的生物活性的探索;胆甾酸的表面两性结构在抗生素、离子通道、分子载体方面的应用;利用其生理循环途径设计、化学合成胆甾酸缀合物以及空间结构的利用研究。     

液相色谱-串联质谱法测定血清中15种胆汁酸

建立了血清中15种胆汁酸的液相色谱-串联质谱(LC-MS/MS)测定方法。血清样品经乙腈沉淀蛋白后,用Capcell Pak C18MG柱分离,以乙腈-醋酸铵缓冲液为流动相进行梯度洗脱,流速0.25 mL/min,进样10μL,采用多反应监测(MRM)定量分析。在定量范围内,15种胆汁酸的线性关系良好,批内、批间的RSD分别为2.3%~12.7%和1.1%~14.3%,回收率在75%~101%之间。应用本法测定了10名健康儿童血清中的胆汁酸含量。该方法的样品处理简单快速,检测准确灵敏,可满足临床血样中胆汁酸含量测定的要求。     

Selective Binding Thermodynamics of Bile Acids by Oligo (ethylenediamino)-β-Cyclodextrins and Their Copper (II) Complexes

Complex stability constants (K _S), standard molar enthalpy changes (ΔH°) and entropy changes (TΔS°) for the inclusion complexation of native β-cyclodextrin (β-CD) (1) and some modified β-CDs, i.e., mono(6-ethylenediamino-6-deoxy)-β-CD (3), mono[6-diethylenetriamino-6-deoxy]-β-CD (4) and their corresponding copper complexes 5 and 6, with four representative bile acid guests, i.e., cholate (CA), deoxycholate (DCA), glycocholate (GCA) and taurocholate (TCA), were determined at 25 °C in aqueous phosphate buffer solution (pH 7.20) by means of isothermal titration microcalorimetry (ITC). The stoichiometry of resulting inclusion complexes between CDs and bile acids was demonstrated by UV and conductivity as well as ITC experiments, showing 1:1 binding model upon all inclusion complexation except for metal-mediated dimer 5. The complex stability constants for modified β-CD 2–4 are dramatically magnified with the extended length of amino tether. As compared with 3 and 4, copper(II) complexes 5 and 6 significantly enhance not only binding ability but also molecular selectivity toward bile guest molecule CA through multipoint recognition, but decreased complexes stability toward TCA could be attributed to the decreased hydrophobic microenvironment of CDs cavity due to the introduction of copper(II) coordination center. Thermodynamically, the resulting complexes between hosts and bile guests are driven absolutely by enthalpy, accompanied by entropy gain or loss. Using the present data and those previously reported for mono(6-amino-6-deoxy)-β-CD (2), thermodynamic behavior and enhanced molecular selectivity could be discussed from the viewpoint of hydrophobic interactions, electrostatic cooperation and van der Waals between the hosts and guests.     

Enzymatic Determination of Urinary Total 7α-Hydroxy Bile Acids

Abstract

An enzymatic determination of urinary 7^α-hydroxy bile acids is described. The principle of the method is as follows: after hydrolysis with β-glucuronidase and solvolysis, the ethyl acetate extract is washed with alkalin solution and water, then the alkali and water washes of the ethyl acetate extract are combined and the solution is acidified to pH 1 and sodium chloride added. Shake solution with ethyl acetate to re-extract the acidic fraction and the ethyl acetate layer is evaporated. Add enzyme color solution of 7_α-hydroxysteroid dehydrogenase (7_α-HSD, from E. coli) to a tube of extract residue and then after incubation, measure the absorbance of the solution.

Excretion values of urinary total 7_α-hydroxy bile acids was measured with patients of acute hepatitis and normal subjects and excretion pattern of 7_α-hydroxy bile acids by the use of chromatographic fractionation was also shown.     

血清中胆汁酸的高效液相色谱荧光测定及质谱鉴定

在Hypersil C18色谱柱上，利用新型荧光试剂1，2-苯并-3，4-二氢咔唑-9-乙基对甲苯磺酸酯（BDETS）作柱前衍生化试剂，采用梯度洗脱对10种胆汁酸（BAs）荧光衍生物进行了优化分离。95℃下在二甲基亚砜溶剂中以柠檬酸钾作催化剂，衍生反应30min后获得稳定的荧光产物，衍生反应完全。激发和发射波长分别为λex=333nm，λem=390nm。采用大气压化学电离源（APCI）正离子模式，实现了血清中胆汁酸的定性和定量测定。线性回归系数均在0.9996以上，线性范围宽，检出限为12．94—21．94fmol。     

气相色谱–质谱法测定人体气味中4种脂肪酸

建立搅拌棒吸附萃取–气相色谱–质谱法测定人体气味中正十二烷酸、正十三烷酸、正十四烷酸、正十六烷酸4种脂肪酸的方法。利用PDMS涂层搅拌吸附棒直接采集人体气味,采用热脱附程序升温进样方式气相色谱法测定人体气味中4种脂肪酸。以7-十三酮为内标,建立了4种脂肪酸的内标定量分析方法,线性范围为20~180ng,相关系数r^2为0.992 0~0.997 5,4种脂肪酸的检出限为3.2~7.5 ng。在40 ng加标水平下,样品加标回收率为90%~105%,测定结果的相对标准偏差为2.7%~4.0%(n=5)。该方法已应用于人体气味化学组分分析,满足分析要求。     

Separation and Determination of Bile Acids in Human Bile by High-Performance Liquid Chromatography

Abstract

A method for simultaneous determination of major bile acids in human bile is described. The unconjugated, glycine- and taurine-conjugated bile acids are extracted with Sep-pak C¹⁸ and separated into groups by ion-exchange chromatography on a lipophilic gel. Subsequently, resolution of each group into ursodeoxycholate, cholate, chenodeoxycholate, deoxycholate and lithocholate is attained into two stages by high-performance liquid chromatography on a Radial-PAK A column. First, 0.3% ammonium phosphate (pH 7.7)/acetonitrile (19:8, v/v) is used for separation of the latter three as a mobile phase. Ursodeoxycholate and cholate are efficiently separated in 0.3% ammonium phosphate (pH 7.7)/acetonitrile (23:8, v/v). The present method is applicable to quantitation of bile acids in human bile with satisfactory accuracy and precision.     

超高效液相色谱快速分析不同哺乳动物胆汁中胆汁酸

建立超高效液相色谱同时快速测定胆汁中13种胆汁酸浓度的方法,并对种内种间差异进行统计学分析.色谱柱为Kyoto C18(100 mm×2.1 mm,2.2 μm);流动相为乙腈-10 mmol/L KH2PO4溶液,梯度洗脱;流速:0.5 mL/min;检测波长200 nm.各种胆汁酸在各自测定浓度范围内与峰面积的线性关系良好(r＞0.9995);所有胆汁酸能够达到良好分离.13种胆汁酸检出限(S/N=3)在0.2～0.6 ng/μL之间.与传统HPLC法相比,本方法简便、快速,精密度高,重现性好,适用于胆汁酸的分析.     

Bile acids and their oxo derivatives: Potential inhibitors of carbonic anhydrase I and II,androgen receptor antagonists and CYP3A4 substrates

Some biological properties of bile acids and their oxo derivatives have not been sufficiently investigated, although the interest in bile acids as signaling molecules is rising. The aim of this work was to evaluate physico‐chemical parametar b (slope) that represents the lipophilicity of the examined molecules and to investigate interactions of bile acids with carbonic anhydrase I, II, androgen receptor and CYP450s. Thirteen candidates were investigated using normal‐phase thin‐layer chromatography in two solvent systems. Retention parameters were used in further quantitative structure–activity relationship analysis and docking studies to predict interactions and binding affinities of examined molecules with enzymes and receptors. Prediction of activity on androgen receptor showed that compounds 3α ‐hydroxy‐12‐oxo‐5β ‐cholanoic and 3α ‐hydroxy‐7‐oxo‐5β ‐cholanoic acid have stronger antiandrogen activity than natural bile acids. The inhibitory potential for carbonic anhydrase I and II was tested and it was concluded that molecules 3α ‐hydroxy‐12‐oxo‐5β ‐cholanoic, 3α ‐hydroxy‐7‐oxo‐5β ‐cholanoic, 3,7,12‐trioxo‐5β ‐cholanoic acid and hyodeoxycholic acid show the best results. Substrate behavior for CYP3A4 was confirmed for all investigated compounds. Oxo derivatives of bile acids show stronger interactions with enzymes and receptors as classical bile acids and lower membranolytic activity compared with them. These significant observations could be valuable in consideration of oxo derivatives as building blocks in medicinal chemistry.