Separation of chiral drugs with sulfobutylether-β-cyclodextrin bycapillary zone electrophoresis

IntroductionChaedcyclodextrlnswerefirstIntroducedby几rabelforchlralseparationofamlnoacids,andthechargedCDcommonlyusednowdaysarecarboxymethyl－p－CD（CM－p－CD）,p－CD－phosphate,Y－CD－phosphate,sulfobutylether－p－cyclodextrln（SBE－p－CD）etc．...     

Simultaneous Chiral Separation of Four H1-Antihistamines by Capillary Zone Electrophoresis Using a Dual Cyclodextrin System

Capillary zone electrophoresis employing a dual cyclodextrin (CD) system, consisting of anionic sulfobutylether-β-CD and native β-CD, was developed for the simultaneous chiral separation of four H1-antihistamine racemates (brompheniramine, chlorpheniramine, cetirizine and promethazine). A cost-effective screening using different native and derivatized, neutral and ionized CDs as chiral selectors was performed to find suitable derivatives for the dual CD system. Under the optimized conditions consisting of 25 mM phosphate background electrolyte at pH 7.0, a combination of 15 mM SBE-β-CD and 10 mM β-CD as chiral selectors, +25 kV applied voltage and 20 °C system temperature, the baseline chiral separation of all racemates was accomplished in less than 8 min. The method proved to be suitable for routine analysis, since it provided satisfactory results during sensitivity, linearity and repeatability studies.

     

Enantioseparation of solriamfetol and its major impurity phenylalaninol by capillary electrophoresis using sulfated gamma cyclodextrin

R-solriamfetol is a recently approved drug used for the treatment of excessive sleepiness associated with narcolepsy and sleep apnea. Herein, a capillary electrophoretic method was developed, enabling the simultaneous analysis of the API and its S-enantiomer in addition to the enantiomers of its major impurity phenylalaninol. Twenty-nine different cyclodextrins (CDs), including native, neutral, and charged ones were screened as potential chiral selectors, and the best results were obtained with sulfated CDs. Randomly sulfated-β-CD exhibited outstanding enantioresolution, the peaks of phenylalaninol enantiomers inserted between the two peaks of solriamfetol enantiomers, while sulfated-γ-CD (S-γ-CD) showed remarkable resolution values in a much shorter analysis time with the optimal enantiomer migration order. Among the single isomer sulfated CD derivatives, substituent dependent enantiomer migration order reversal could also be observed in the case of heptakis(6-O-sulfo)-β-CD (HS-β-CD) or heptakis(2,3-O-dimethyl-6-O-sulfo)-β-CD (HDMS-β-CD) with R-,S-solriamfetol, and heptakis(2,3-O-diacetyl-6-O-sulfo)-β-CD (HDAS-β-CD) resulting S-,R-solriamfetol migration order. The sulfated-γ-CD system was chosen for method optimization applying orthogonal experimental design. The optimized method (45 mM Tris-acetate buffer, pH 4.5, 4 mM S-γ-CD, 21°C, +19.5 kV) was capable for the baseline separation of solriamfetol and phenylalaninol enantiomers within 7 min. The optimized method was validated according to the ICH guidelines and successfully applied for the analysis of pharmaceutical preparation (Sunosi^® 75 mg tablet), thus it may serve as a routine procedure for the laboratories of regulatory authorities as well as in Pharmacopoeias.     

Enantioseparation of the New Antifungal Drug Iodiconazole and Structurally Related Triadimenol Analogues by CE with Neutral Cyclodextrin Additives

Chiral separation of iodiconazole, a new antifungal drug, and 12 new structurally related triadimenol analogues were studied by capillary electrophoresis with seven neutral cyclodextrins. It was found that hydroxypropyl-γ-cyclodextrin (HP-γ-CD) was the most effective chiral selector. Furthermore, the influence of the concentration of HP-γ-CD, buffer pH, buffer concentration, temperature, and applied voltage was investigated, and the method was validated. The study of the analyte structure-enantioseparation relationships showed that substitutions in the side chains had important influences on enantiomeric separation.     

毛细管电泳法和高效液相色谱法拆分联萘二酚酸对映体

采用毛细管电泳法和高效液相色谱法直接拆分2,2′-二羟基-1,1′-联二萘-3,3′-二甲酸(HBNC)对映体.以四种不同的β-环糊精为手性添加剂,考察环糊精的种类与浓度、缓冲液pH值及浓度、分离电压、温度等因素对HBNC分离的影响.结果表明:采用10 mmol/L磺丁基醚-β-环糊精+20 mmol/L磷酸盐缓冲液(pH=7.0),20 kV分离电压,HBNC对映体在20 min内达到基线分离,分离度达到3.31.采用(S)-叔-亮氨酸基-(S)-1-(α-萘基)乙胺手性柱,正己烷-乙醇-三氟乙酸(97∶3∶0.2,V/V)流动相,HBNC对映体在40 min内也基本达到基线分离.     

新型三唑类抗真菌活性化合物毛细管电泳手性拆分及手性识别机理分子模拟研究

研究了7种新型三唑类抗真菌活性化合物的毛细管电泳法手性分离,利用计算机辅助分子模拟技术研究拆分机理。考察了8种中性环糊精手性添加剂,只有2,6-二甲基-β-环糊精对7种活性化合物都有手性识别能力。在30mmol/L NaH2PO4缓冲液中含2,6-二甲基-β-环糊精30mmol/L,用H3PO4调至pH 2.2,温度20℃,电压20kV,在此条件下7种活性化合物都能达到手性分离,其中4种活性化合物能达到基线分离(Rs>1.5)。应用计算机辅助分子模拟软件Discovery Studio 2.5/Sybyl/Gold模拟2,6-二甲基-β-环糊精与7种活性化合物主客体包结过程,并计算相互结合能,探讨手性识别机理,发现拆分结果与结合能的差异有关,结合能差异越大拆分结果越好。     

Optimized Conditions of Enantioseparation of β-Blockers by CZE Using Carboxymethyl-β-Cyclodextrin as Chiral Selector

Capillary zone electrophoresis was used for the enantiomeric separation of six β-blocking drug substances with β-cyclodextrin (β-CD) and its derivatives as chiral selectors employing an uncoated capillary. The effects of pH value and composition of the background electrolyte (BGE), the capillary temperature and running voltage have been investigated. The results showed that β-CD type, concentration and pH value have a strong influence on the efficiency of the chiral separation. Carboxymethyl-β-cyclodextrin (CM-β-CD) gave a baseline enantiomeric separation for six β-blocking drug substances under optimal conditions, whereas the β-CD, hydroxypropyl-β-cyclodextrin (HP-β-CD) showed no chiral recognition. The potential and capillary temperature did not have a great effect on enantiomer resolution.     

毛细管区带电泳对手性药物盐酸美西律和盐酸异博定的对映体分离

应用环糊精-毛细管区带电泳体系对手性药物盐酸美西律和盐酸异博定的对映体分离进行了研究。结果表明, 在所研究的手性选择剂α-环糊精, β-环糊精, 二甲基-β-环糊精, 羟丙基β-环糊精和γ-环糊精中, 羟丙基β-环糊精对所研究的手性药物分离效果较好。对盐酸美西律和盐酸异博定的最佳羟丙基-β-环糊精浓度分别为30mmol/L和9mmol/L, 最佳缓冲溶液浓度为100mmol/L Tris-H3PO4(pH2.3)。向缓冲溶液中加入0.05%羟丙基纤维素(HPLC)可改善分离。盐酸美西律获得了接近基线的手性分离, 而盐酸异博定亦获得了较好的分离。     

Enantiomeric analysis of rivastigmine in pharmaceuticals by cyclodextrin-modified capillary zone electrophoresis

Chiral separation method development is usually very time-consuming due to the diversity in chemical structures of pharmaceutical drug substances as well as the suitable separation conditions and the problem to choose the appropriate chiral selector. This paper shows capillary zone electrophoresis (CZE) which was developed for chiral separation of a basic compound - rivastigmine (RIV) using 30 cm × 50 μm i.d. polyacrylamide (PAA)-coated fused-silica capillary (effective length 20 cm), amine-modified phosphate buffer of pH 2.5 and sulfated-β-CD (S-β-CD) as chiral selector. Other selected native or derivatized cyclodextrins (CDs) were also tested: β-CD (5, 30 mM), carboxymethyl-β-CD (5, 30 mM), dimethyl-β-CD (15 mM), hydroxypropyl-β-CD (5, 30 mM), hydroxypropyl-α-CD (5, 30 mM) and hydroxypropyl-γ-CD (5, 30 mM). Complete enantiomeric separation of RIV was achieved at 20 kV, 18 °C and detection at 200 nm within 8 min with R.S.D. for the absolute migration time reproducibility of less than 2.1%. Rectilinear calibration range was 5.0-500.0 μM of each enantiomer (r = 0.9994-0.9995). The CZE method proposed was used for the control of chiral purity of pharmaceutically active S-RIV and for the analysis of Exelon caps preparation.     

Chiral recognition of imperanene enantiomers by various cyclodextrins: a capillary electrophoresis and NMR spectroscopy study

The enantiomers of imperanene, a novel polyphenolic compound of Imperata cylindrica (L.), were separated via cyclodextrin-modified capillary electrophoresis. The anionic form of the analyte at pH 9.0 was subject to complexation and enantioseparation CE studies with neutral and charged cyclodextrins. As chiral selectors 27 CDs were applied differing in cavity size, sidechain, degree of substitution (DS) and charge. Three hydroxypropylated and three sulfoalkylated CD preparations provided enantioseparation and the migration order was successfully interpreted in each case in terms of complex mobilities and stability constants. The best enantioresolution (R(S) =?1.26) was achieved using sulfobutyl-ether-γ-CD (DS ～4), but it could be enhanced by extensive investigations on dual selector systems. After optimization (CD concentrations and pH) R(S) =?4.47 was achieved using a 12.5 mM sulfobutyl-ether-γ-CD and 10 mM 6-monodeoxy-6-mono-(3-hydroxy)-propylamino-β-cyclodextrin dual system. The average stoichiometry of the complex was determined with Job's method using NMR-titration and resulted in a 1:1 complex for both (2-hydroxy)propyl-β- and sulfobutyl-ether-γ-CD. Further NMR experiments suggest that the coniferyl moiety of imperanene is involved in the host-guest interaction.     

Chiral separation of newly synthesized arylpropionic acids by capillary electrophoresis using cyclodextrins or a glycopeptide antibiotic as chiral selectors

Summary The chiral separation of two newly synthesized arylpropionic acids of pharmaceutical interest, namely 2-[(5′-benzoil-2′-hydroxy)phenyl]-propionic acid (DF-1738y) and 2-[(4′-benzoiloxy-2′-hydroxy)phenyl]-propionic acid (DF-1770y), was performed by Capillary Zone Electrophoresis (CZE) using either cyclodextrins or antibiotics as chiral selectors in coated capillary. In order to optimize the separation, the effect on the migration time and resolution of type and concentration of the chiral selector, the buffer pH and the capillary temperature were studied. Several cyclodextrins, namely the charged 6^A-monomethylamino-β-cyclodextrin (MeNH-β-CD) and the neutral methyl-β-cyclodextrins (M-β-CD) and heptakis-2,3,6-tri-O-methyl-β-cyclodextrin (TM-β-CD), were tested for the enantiomeric separation of aryl propionic acids (APAs) compounds. Of these TM-β-CD provided the highest enantiomeric resolution at pH 5, however only DF-1738y optical isomers were baseline resolved. Using background electrolytes (BGEs) at higher pHs (pH=6–7) supported with the above listed CDs, an enantioresolution increase was recognized only for compound DF-1738y. In contrast DF-1770y exhibited the highest resolution at the lowest pH value studied (pH 4). The macrocyclic antibiotic vancomycin was therefore added to the BGE and tested as chiral selector using the partial filling counter current mode in order to obtain a sensitive analysis, high resolution and reduced antibiotic adsorption on the capillary wall. 5 mM vancomycin dissolved in the BGE at pH 5 and 25°C provided relatively high enantiomeric resolution (R _DF-1738y=3.4,R _DF-1770y=2.22) of both compounds.     

Determination of aminoglutethimide enantiomers in pharmaceutical formulations by capillary electrophoresis using methylated-β-cyclodextrin as a chiral selector and computational calculation for their respective inclusion complexes

A capillary electrophoretic method for the separation of the aminoglutethimide (AGT) enantiomers using methylated-β-cyclodextrin (M-β-CD) as chiral selector is described. Several parameters affecting the separation were studied, including the type and concentration of chiral selector, buffer pH, voltage and temperature. Good chiral separation of the racemic mixture was achieved in less than 9 min with resolution factor Rs = 2.1, using a fused-silica capillary and a background electrolyte (BGE) of tris-phosphate buffer solution (50 mmol L⁻¹, pH 3.0) containing 30 mg mL⁻¹ of M-β-CD. The separation was carried out in normal polarity mode at 25 °C, 16 kV and using hydrostatic injection. Acceptable validation criteria for selectivity, linearity, precision, and accuracy/recovery were included. The proposed method was successfully applied to the assay of AGT enantiomers in pharmaceutical formulations. The computational calculations for the inclusion complexes of the R- and S-AGT-M-β-CD rationalized the reasons for the different migration times between the AGT enantiomers.     

手性流动相添加法拆分酮康唑外消旋体

采用C18反相色谱柱,利用在流动相中加入手性选择剂的方法实现酮康唑对映体的拆分。研究了手性选择剂的种类及浓度、流动相pH值、甲醇比例和柱温等因素对酮康唑手性分离的影响,结果表明磺丁基-β-环糊精可以使酮康唑对映体完全分离,最后选择的流动相组成为甲醇-0.02 mol/L磷酸二氢钠(体积比为60∶40,含0.02%三乙胺和1.0 mmol/L磺丁基-β-环糊精,用稀磷酸调节pH值到3.00)。酮康唑对映体在6 min内得到基线分离,分离度为2.05。方法简便,分离效果好,对酮康唑对映体的拆分具有应用价值。     

Enantiomeric separation of alanyl and leucyl dipeptides by capillary electrophoresis with cyclodextrins as chiral selectors

Eight neutral cyclodextrins were tested for the enantiomeric separation of alanyl and leucyl dipeptides by capillary electrophoresis at pH 3, and seven out of the eight cyclodextrins proved suitable for the separation of one or more of the dipeptide enantiomer pairs. The best results were obtained with heptakis(2,6-di-O-methyl)-beta-cyclodextrin. The dipeptides that were separated were mainly the aromatic and the more lipophilic aliphatic dipeptides. Mobility difference plots at pH 3.0 with malonic acid-triethanolamine as background electrolyte showed that the aromatic dipeptides had higher affinities for the cyclodextrin than the nonpolar, aliphatic dipeptides. The results suggested that, under the conditions applied, the C-terminal amino acid rather than the N-terminal one is involved in the chiral discrimination.     

β-环糊精衍生物与吡罗昔康的包合特性

采用荧光光谱、差热扫描和核磁共振法,研究了不同酸度下吡罗昔康（PX）与β-环糊精（β-CD）、羟丙基-β-环糊精（HP-β-CD）和磺丁醚-β-环糊精（SBE-β-CD）的包合特性。 结果表明,吡罗昔康与3种环糊精均形成了1∶2.5的包合物。 以包合常数为包合能力的量度,中性条件下,包合平衡常数分别为1.2×106、1.8×106、2.0×106,3种环糊精的包合能力为SBE-β-CD＞HP-β-CD＞β-CD。     

Enantiodifferentiation of N-benzyloxycarbonylaminophosphonic and phosphinic acids and their esters using cyclodextrins by means of capillary electrophoresis

Capillary electrophoresis was successfully applied for separation of the enantiomers of N-benzyloxycarbonyl-alpha-aminophosphonic and alpha-aminophosphinic acids as well as their ethyl and phenyl monoesters with the use of a range of commercially available cyclodextrins (alpha, beta and hydroxypropyl-gamma-cyclodextrins) as chiral selectors. The dependence of effectiveness of separation on type and concentration of these chiral selectors as well as on pH of background electrolyte was examined in some detail.     

3-位烯丙基及甲基衍生的β-环糊精固定相的合成及气相色谱性能研究

制备了一种新的β-环糊精衍生物固定相2,6-二-O-戊基-3-O-[(甲基)5(烯丙基)2]-β-CD,并对其气相色谱分离性能进行研究。实验显示,该固定相具有良好的柱表面性能和较强的色谱分离能力,对一些芳香族位置异构体的分离能力优于2,6-二-O-戊基-3-O-烯丙基-β-CD衍生物,对10余种手性物质显示出较好的选择性能,且对α-位取代的丙酸酯类手性分离效果明显优于杂环类β-CD衍生物。与2,6-二-O-戊基-3-O-烯丙基-β-CD固定相的分离性能比较表明,β-CD 3位羟基部分甲基基团的引入能增强对芳香族位置异构体的选择能力,但不能明显改变烯丙基衍生物的手性分离能力。     

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.     

Simultaneous Chiral Separation of Geometry Isomers and Enantiomers of Nateglinide by Capillary Electrophoresis with Mixture of CD Derivations as Chiral Selector

Abstract

A capillary electrophoresis (CE) method for the simultaneous separation of geometry isomers and enantiomers of nateglinide was built. Several different dyclodextrin (CD) derivatives were tested for the chiral separation of nateglinide, and it was proved that ionic CDs [i.e., carboxymethy-β-CD (CM-β-CD) and sulphonic-β-CD (S-β-CD)] could show better chiral selectivity for both geometry isomers and enantiomers than the neutral CDs. The separation of geometry of both isomers and enantiomers of nateglinide was obtained by CE in a 75-µm i.d. × 60 cm (effective length 45 cm) fused-silica capillary at 11 kV voltage, while 30 mM phosphate (pH = 8.38) acted as running buffer and a mixture of 40 mM S-β-CD + 21 mM CM-β-CD served as chiral selector. The detective wavelength was set at 254 nm.     

Enantioseparation of dansyl amino acids and dipeptides by chiral ligand exchange capillary electrophoresis based on Zn(II)-l-hydroxyproline complexes coordinating with γ-cyclodextrins

A chiral ligand exchange capillary electrophoresis (CLE-CE) method using Zn(II) as the central ion and l-4-hydroxyproline as the chiral ligand coordinating with γ-cyclodextrin (γ-CD) was developed for the enantioseparation of amino acids (AAs) and dipeptides. The effects of various separation parameters, including the pH of the running buffer, the ratio of Zn(II) to l-4-hydroxyproline, the concentration of complexes and cyclodextrins (CDs) were systematically investigated. After optimization, it has been found that eight pairs of labeled AAs and six pairs of labeled dipeptides could be baseline-separated with a running electrolyte of 100.0 mM boric acid, 5.0 mM ammonium acetate, 3.0 mM Zn(II), 6.0 mM l-hydroxyproline and 4.0 mM γ-CD at pH 8.2. The quantitation of AAs and dipeptides was conducted and good linearity (r² ≥ 0.997) and favorable repeatability (RSD ≤ 3.6%) were obtained. Furthermore, the proposed method was applied in determining the enantiomeric purity of AAs and dipeptides. Meanwhile, the possible enantiorecognition mechanism based on the synergistic effect of chiral metal complexes and γ-CD was explored and discussed briefly.