手性流动相HPLC法拆分萘普生对映体的研究

将β-环糊精、甲基-β-环糊精、羟丙基-β-环糊精、L-脯氨酸作为手性流动相添加剂,系统地研究了D,L-萘普生在RP-HPLC系统中的拆分.分别考察了手性流动相的种类,手性试剂羟丙基-β-环糊精的浓度,流动相的pH值,修饰剂的种类及浓度,三乙胺浓度和柱温等对拆分效果的影响,以HP-β-CD为手性流动相添加剂,建立了HP-β-CD手性流动相分离萘普生对映体的方法.结果表明：当流动相为25 mol/L HP-β-CD、体积分数15%乙醇、体积分数0.5%三乙胺、pH3.5、柱温t25℃、流速V=1 mL/min时萘普生对映体得到了良好的基线分离,分离因子α可达1.29.     

β-环糊精及其衍生物手性添加剂HPLC法拆分氯噻酮对映体过程热力学研究

以Me-β-环糊精为手性流动相添加剂，于Lichrospher C18反相柱上建立了氯噻酮对映体高效液相色谱拆分方法，同时改进了β-环糊精、HP-β-环糊精为手性流动相添加剂拆分氯噻酮对映体的色谱条件，并着重研究了在25-45℃范围内Me-β-CD、β-CD和HP-β-CD为手性流动相添加剂拆分氯噻酮对映体的过程热力学并结合手性药物氯噻酮所得的热力学数据对环糊精及其衍生物拆分能力的差异进行了比较和分析。结果表明都属于焓控过程，其拆分能力的不同主要是因为手性添加剂与对映体形成氢键作用、空间位阻效应和立体构象匹配程度存在差异。     

6-O-磺丁基-β-环糊精的合成及在非水毛细管电泳拆分碱性手性药物中的应用

合成了新型环糊精衍生物6-O-磺丁基-β-环糊精(SB-β-CD),并以其作为手性选择剂,对扑尔敏、多西拉敏、美克洛嗪和米安舍林4种碱性手性药物进行非水毛细管电泳拆分。考察了有机溶剂、电解质、手性选择剂浓度以及pH对分离度的影响。研究结果表明:扑尔敏、多西拉敏、美克洛嗪和米安舍林4种碱性手性药物全部达到基线分离。可见SB-β-CD在碱性药物拆分方面具有特殊能力,为碱性手性药物的拆分提供了一种准确、简便的分析方法。     

MAH-β-CD的合成及其在毛细管电泳手性拆分中的应用

合成了顺丁烯二酸酐-β-环糊精(MAH-β-CD),并通过红外光谱、质谱对其结构进行表征。以20 mmol/L乙酸铵为缓冲溶液,MAH-β-CD作为手性选择剂,利用毛细管电泳对氨基酸和手性药物对映体进行拆分研究。考察了缓冲溶液pH、分离电压和手性选择剂浓度等对拆分效果的影响,在优化条件下,成功拆分了3种氨基酸(DL-甲硫氨酸、DL-精氨酸、DL-赖氨酸)和两种手性药物(沙丁胺醇、氯美扎酮)对映体,分离度分别为5.11,5.55,2.99,2.33和1.64。     

HP-β-CD手性流动相HPLC法拆分萘普生对映体的色谱保留机制和拆分机理研究

研究了HPLC法羟丙基_β_环糊精(HP_β_CD)手性流动相添加剂对萘普生对映体的保留机制,建立了保留因子与[CD]、[H ]、包结常数以及萘普生的解离常数的关系式,并结合实验对此关系式进行了验证,结果表明此关系式对手性添加剂、pH等因素对拆分的影响具有一定的理论指导。保留因子(k)的倒数1k对HP_β_CD的浓度呈良好的线性关系,证明HP_β_CD与萘普生对映体形成的包合比是11包合物。计算了手性分离过程中的热力学参数,结果表明HP_β_CD对萘普生对映体的分离过程主要是一个焓驱动的过程,包合过程是一个放热过程。通过比较手性选择体结构,探讨了HP_β_CD拆分萘普生对映体的机理,进一步分析表明HP_β_CD能拆分萘普生对映体的主要因素是尺寸大小相匹配、构象诱导作用和偶极_偶极作用。     

UPA-β-CD的合成及其在CE手性拆分中的应用

以6-乙二胺-β-CD和马来酸酐为原料,合成了6-(N-乙基氨基马来酸)-氨基-β-CD(UPA-β-CD),并以此为手性选择剂,利用毛细管电泳法对2种手性药物进行拆分。分别考察了手性选择剂浓度、缓冲溶液pH、分离电压和温度等对拆分效果的影响,在β-环糊精15 mmol/L,缓冲液pH 3.5和pH 4,分离电压18 k V和20 k V,分离温度20℃时,盐酸克伦特罗和非尼拉敏2种手性药物均达到基线分离,分离度分别为1.98和1.62。     

Chiral Separation and Optical Purity Determination of Naproxen and Its Esters by Capillary Electrophoresis with Sulfonated

以磺化β－环糊精作为手性分离添加剂,分别对萘普生、萘普生甲酯和萘普生氯乙酯进行了毛细管电泳手性分离研究,当以含40g/L的磺化β－环糊精的0.010mol/L的三羟甲基氨基甲烷－柠檬酸为缓冲液（pH5.0）时,上述3种化合物的手性分离度分别为2.19、2.60和1.99。手性化合物的出峰时间和校正峰面积的相对标准偏差分别为2.84％和6.26％,而两对映体的相对出峰时间和相对校正峰面积的相对标准偏差分别为0.52％和1.86％。对萘普生和萘普生氯乙酯的实际样品进行了光学纯度测定,测定结果与HPLC进行了比较。     

用羧甲基聚合环糊精作手性剂的毛细电泳法分离3种碱性药物

采用5种环糊精衍生物对碱性药物--硫喷妥钠、盐酸氟桂利嗪、山梗菜碱进行了毛细管区带电泳的手性拆分.结果表明,采用含2%(质量分数,其余相同)聚合β-环糊精(P-β-CD)或0.5%羧甲基聚合β-环糊精(CM-P-β-CD)30 mmol/L的Tris-H3PO4缓冲液可使这3种药物达到基线分离;使用CM-P-β-CD时,分离度高达4～35.     

薄层色谱法拆分手性药物对映体

用性能稳定的薄层色谱用β-环糊精(β-CD)、硅胶手性固定相拆分手性药物对映体.在适当比例的乙腈-1%乙酸三乙胺(TEAA)、己烷-异丙醇、乙腈-甲醇-乙酸-三乙胺、甲醇-1%TEAA及乙腈-1%TEAA-三乙胺溶剂系统中展开,8种临床常用的手性药物对映体得到有效分离,对映异构体之间的相对比移值α为1.53～4.89.     

衍生化β-环糊精手性固定相高效液相色谱法拆分米那普仑对映体及其分离机制

建立了新型抗抑郁药米那普仑在环糊精手性固定相上的高效液相色谱拆分方法。在反相色谱条件下采用未衍生化β-环糊精(Cyclobond I 2000)、乙酰基-β-环糊精(AC-β-CD)、2,3-二甲基-β-环糊精(DM-β-CD)、3,5-二甲基苯基氨基甲酸酯-β-环糊精(DMP-β-CD)4种手性柱分离米那普仑对映体。考察了固定相、流动相比例、pH、流速和柱温对拆分的影响。利用分子对接和结合能计算方法,研究米那普仑分子与AC-β-CD的对接过程,探讨其可能的分离机制。优化后的拆分条件如下:固定相为乙酰基-β-环糊精手性柱Astec CYCLOBONDTMI 2000 AC(25 cm×4.6 mm,5μm),流动相为乙腈-0.1%(体积分数)pH 5.0醋酸三乙胺溶液(TEAA)(5∶95,v/v),流速为0.4mL/min,柱温为25℃,检测波长为220 nm。在此条件下,米那普仑对映体获得快速拆分,分离度(Rs)为1.74,理论塔板数为10 125。分子模拟结果表明引起手性识别的作用力主要是环糊精衍生化的乙酰基导致的氢键作用差异。该方法快速、高效、重现性好。     

Separation of brompheniramine enantiomers by capillary electrophoresis and study of chiral recognition mechanisms of cyclodextrins using NMR-spectroscopy, UV spectrometry, electrospray ionization mass spectrometry and X-ray crystallography

Opposite migration order was observed for the enantiomers of brompheniramine [N-[3-(4-bromphenyl)-3-(2-pyridyl)propyl]-N,N-dimethylamine] (BrPh) in capillary electrophoresis (CE) when native beta-cyclodextrin (beta-CD) and heptakis(2,3,6-tri-O-methyl)-beta-CD (TM-beta-CD) were used as chiral selectors. NMR spectrometry was applied in order to obtain information about the stoichiometry, binding constants and structure of the selector-selectand complexes in solution. The data were further confirmed by UV spectrometry and electrospray ionization mass spectrometry. The structure of the complexes in the solid state was determined using X-ray crystallography performed on the co-crystals precipitated from the 1:1 aqueous solution of selector and selectand. This multiple approach allowed an elucidation of the most likely structural reason for a different affinity (binding strength) of BrPh enantiomers towards beta-CD and TM-beta-CD. However, the question about a force responsible for the opposite affinity pattern of BrPh enantiomers towards these CDs could not be answered definitely.     

Migration order of dipeptide and tripeptide enantiomers in the presence of single isomer and randomly sulfated cyclodextrins as a function of pH

The present study was conducted in order to evaluate the cyclodextrin (CD)-mediated chiral separation of peptide enantiomers as uncharged analytes at pH 5.3 using randomly sulfated beta-cyclodextrin, heptakis-6-sulfato-beta-CD and heptakis-(2,3-diacetyl-6-sulfato)-beta-CD as chiral selectors. Although less effective compared to stronger acidic conditions, the CDs proved to be suitable chiral selectors for the present set of peptides at pH 5.3. The carrier ability of the negatively charged CDs upon reversal of the applied voltage may also be exploited leading to a reversal of the migration order. In addition, reversal of the enantiomer migration order upon increasing the buffer pH from 2.5 to 5.3 was also observed for Ala-Tyr in the presence of randomly sulfated beta-CD, for Ala-Phe, Ala-Tyr, Phe-Phe, Asp-PheNH(2) and Gly-Ala-Phe in the presence of heptakis-6-sulfato-beta-CD, and for Phe-Phe and Ala-Leu in the presence of heptakis-(2,3-diacetyl-6-sulfato)-beta-CD. The migration behavior could be explained on the basis of the complexation constants and the mobilities of the peptide-CD complexes. While a change in the affinity pattern of the CDs upon increasing the pH was observed for some peptides, complex mobility was the primary factor for other peptide-CD combinations affecting the enantiomer migration order at the two pH values studied.     

毛细管电泳法手性拆分合成药物氨氯地平及其中间体

 建立了毛细管电泳手性拆分氨氯地平药物中间体的方法 ,并同时拆分了氨氯地平。考察了不同手性拆分试剂对手性选择性的影响 ,其中羧甲基 β 环糊精 (CM β CD)能够给出满意的拆分结果。在以CM β CD为手性拆分试剂的基础上 ,还考察了各种因素诸如流动相的pH值、环糊精的浓度以及电压对分离的影响。最佳拆分条件为 :30mmol/L磷酸盐 +5 0mmol/LCM β CD(pH 6 12 )。在此条件下 ,药物中间体及氨氯地平的分离度分别为 1 5 5和 1 73,结果令人满意。     

Enantioselective separation of azole compounds by EKC. Reversal of migration order of enantiomers with CD concentration

The enantioselective separation of a group of six weak base azole compounds was achieved in this work using EKC with three neutral beta-CDs as chiral selectors. The native beta-CD and two other beta-CD derivatives with different types and positions of the substituents on the CD rim ((2-hydroxy)propyl-beta-CD (HP-beta-CD) and heptakis-2,3,6-tri-O-methyl-beta-CD (TM-beta-CD)) were employed. Apparent binding constants for each pair compound-CD were determined in order to study analyte-CD interactions. The best enantiomeric resolutions for miconazole, econazole, and sulconazole were observed with HP-beta-CD whereas for the separation of the enantiomers of ketoconazole, terconazole, and bifonazole, TM-beta-CD was the best chiral selector. The enantioseparations obtained were discussed on the basis of the structure of the compounds taking into account that inclusion into the hydrophobic CD cavity occurred through the phenyl ring closer to the azole group. In addition, a change in the migration order for the enantiomers of two of the compounds studied (ketoconazole and terconazole) with the concentration of HP-beta-CD was observed for the first time.     

α-萘基缩水甘油醚对映体的毛细管区带电泳手性拆分

建立了毛细管区带电泳手性拆分α-萘基缩水甘油醚对映体的方法.考察了不同手性拆分试剂对手性选择性的影响,实验结果表明,20 mmol/L H3PO4-三乙醇胺(pH 2.5)、2%(w/V)HS-β-CD、毛细管温度20 ℃、运行电压-18 kV为最佳分离条件,在该分离条件下α-萘基缩水甘油醚对映体实现基线分离.方法简便、准确,可用于α-萘基缩水甘油醚的手性拆分和对映体过量值(ee,%)测定.     

Fast enantiomeric separation of basis drugs by electrokinetic chromatography. Application to the quantitation of terbutaline in a pharmaceutical preparation

Electrokinetic chromatography (EKC) using micelles of bile salts alone or mixed with sodium dodecyl sulfate (SDS) and neutral, anionic, or cationic cyclodextrins (CDs) in the separation buffer has been employed in order to achieve fast enantiomeric separation of basic drugs. A study of the enantiomeric separation ability of these chiral selectors concerning four basic drugs (epinephrine, terbutaline, clenbuterol, and salbutamol) has been carried out under different experimental conditions. The best chiral selectors to perform the enantiomeric separation of these drugs were neutral beta-CD derivatives, specifically permethylated beta-CD PM-beta-CD. The effect of the PM-beta-CD concentration, temperature, and applied voltage on the enantiomeric resolution of the basic drugs was investigated. The use of a 25 mM ammonium acetate buffer (pH 5.0), 30 mM in PM-beta-CD together with an applied voltage of 20 kV and a temperature of 15 degrees C enabled the individual and fast enantiomeric separation of epinephrine, norepinephrine, terbutaline, clenbuterol, and salbutamol each one into its two enantiomers in less than 3 min. The EKC method was validated (precision and accuracy) to quantitate terbutaline in a pharmaceutical preparation, obtaining a limit of detection of 4 microg/mL.     

On-line coupling of partial filling-capillary zone electrophoresis with mass spectrometry for the separation of clenbuterol enantiomers

The on-line coupling of capillary zone electrophoresis with mass spectrometry (CZE-MS) for the separation of enantiomers is hampered by the presence of nonvolatile chiral selectors such as cyclodextrins in the separation buffer. This problem can be overcome by use of the partial filling technique where only a part of the capillary is filled with the separation buffer containing chiral selectors. Since the electroosmotic flow is almost completely suppressed at acidic pH, that dimethyl-beta-cyclodextrin is neutral, no free cyclodextrin would reach the MS detector when using a partially filled capillary. By this method, clenbuterol enantiomers were successfully resolved and separated from salbutamol (internal standard) in aqueous solution and in plasma samples. A solid-phase extraction (SPE) was used for the preparation of plasma samples before analysis.     

Enantioseparation of thalidomide and its hydroxylated metabolites using capillary electrophoresis with various cyclodextrins and their combinations as chiral buffer additives.

The separation of thalidomide (TD) and its hydroxylated metabolites including their simultaneous enantioseparation was studied in capillary electrophoresis (CE) using four different randomly substituted charged cyclodextrin (CD) derivatives, the combinations of some of them with each other, and beta-CD. TD, as well as two metabolites recently found in incubations of human liver microsomes and human blood, 5-hydroxythalidomide (5-OH-TD) and one of the diastereomeric 5'-hydroxythalidomides (5'-OH-TD), are neutral compounds. Therefore, they were resolved using charged chiral selectors in CE. Two different separation modes (normal polarity and carrier mode) and two different capillaries (fused-silica and polyacrylamide-coated) were tested. Based on the behavior of the individual CDs, their designed combinations were selected in order to improve the separation selectivity and enantioselectivity. Under optimized conditions all three chiral compounds and their enantiomers were resolved simultaneously.     

Enantioseparation of chiral allenic acids by micellar electrokinetic chromatography with cyclodextrins as chiral selector

Enantioseparation of chiral aryl allenic acids by micellar electrokinetic chromatography (MEKC) with cyclodextrins (CDs) as chiral selectors was described. The screen of chiral selectors (beta-CD, gamma-CD, and hydroxypropyl (HP)-gamma-CD) showed that the enantioseparation was not only dependent on the type of CD but also the presence of 2-propanol in the buffer. In order to optimize the operational parameters, the effect of the concentration of CDs, sodium dodecyl sulfate (SDS), and 2-propanol, as well as the buffer ionic strength and pH on enantioseparation were studied. It was proved that the concentration of CDs, 2-propanol, and the buffer ionic strength were the critical parameters. Under optimal conditions, baseline separations of all seven allenic acid enantiomers were achieved. Furthermore, the method validation in terms of repeatability, linearity, limit of detection (LOD), and limit of quantitation (LOQ) were performed. Using the present method, the optical purity of a nonracemic sample with the enantiomeric excess (e.e.%) value of 99.65% was determined.     

Inclusion complexes of Fe(III) tetrakis(4-sulfonatophenyl)porphyrin with cyclodextrins in aqueous solutions

In aqueous solutions, inclusion complexation of Fe(III) tetrakis(4-sulfonatophenyl)porphyrin (FeTSPP) with alpha-cyclodextrin (alpha-CD), beta-CD, gamma-CD, and heptakis(2,3,6-tri-O-methyl)-beta-CD (TM-beta-CD) has been examined by means of absorption and induced circular dichroism spectroscopy. FeTSPP has been found to form inclusion complexes with beta-CD, gamma-CD, and TM-beta-CD in pH 3.2 buffers. At pH 10.1, where FeTSPP self-associates to form an oxo-bridged dimer, FeTSPP also forms inclusion complexes with alpha-CD, beta-CD, gamma-CD, and TM-beta-CD. The stoichiometries of the CD-FeTSPP inclusion complexes are 1:1, except for TM-beta-CD in pH 10.1 buffers where its 1:1 inclusion complex associates with TM-beta-CD to form a 2:1 inclusion complex at high TM-beta-CD concentrations. Equilibrium constants of FeTSPP for the formation of the 1:1 inclusion complexes have been evaluated for beta-CD, gamma-CD, and TM-beta-CD. Induced circular dichroism spectra of FeTSPP in alpha-CD and beta-CD solutions exhibit a signal pattern (a negative sign) that is different from those in acidic and basic solutions containing gamma-CD and that in basic solution containing TM-beta-CD, suggesting different inclusion modes towards FeTSPP.