手性药物的物理和化学性质非常相似。然而,它们的药理和毒理学作用差异很大。例如,一种对映体可能具有有利的性质,而另一种可能无效或甚至具有毒副作用。因此,探索提高对映体分辨率的创新策略具有重要意义。美托洛尔(MET)是一种用于治疗高血压的β受体阻滞剂,稳定型心绞痛,室上性快速性心律失常.建立MET对映体的手性分离分析方法对于提高手性药物的质量具有重要意义。毛细管电泳(CE)具有样本量小的优点,操作简单,分离效率高,多种替代方式,因此在手性药物分离领域得到了广泛的应用。通常用于基于CE的手性分离的手性选择剂包括环糊精(CD)及其衍生物,多糖,蛋白质,和大环抗生素.CD是CE最常用和有效的手性选择剂之一。CD的腔内相对疏水结构和腔外相对亲水结构使其与手性分子形成具有不同结合常数的包合物,从而实现手性分离。然而,单独使用CD作为手性选择剂并不总是产生令人满意的分离结果。因此,添加其他添加剂,离子液体和低共熔溶剂(DESs)等辅助CD基手性分离体系受到了广泛的关注。先前关于通过CE分离MET的对映体的研究集中在单独添加CD及其衍生物用于分离。关于向CD中协同添加辅助添加剂以改善MET的对映体拆分的研究很少。在这项研究中,三个DES,即,氯化胆碱-D-葡萄糖,氯化胆碱-D-果糖,和乳酸-D-葡萄糖,首次用于基于CE的MET手性分离,推测了DES对CD毛细管区带电泳分离MET对映体的协同作用。为此,内径为50μm的无涂层熔融石英毛细管,分离柱总长度为50cm,有效长度为41.5cm。首先,CD类型的影响,CD浓度,缓冲液pH值,和缓冲液浓度对MET分离的影响进行了研究,和最佳条件(15mmol/L羧甲基-β-环糊精(CM-β-CD),pH=3.0,并获得40mmol/L磷酸盐缓冲液)。其他CE条件如下:230nm处的UV检测,25kV的施加电压。所有操作均在20℃下进行。接下来,通过混合加热方法制备了三种类型的DES作为辅助添加剂。将DESs以一定的摩尔比在50mL圆底烧瓶中混合,然后在80°C水浴中加热3h直到获得澄清透明的液体。随后研究了不同DES及其质量分数对手性分离的影响。最终确定最佳氯化胆碱-D-果糖质量分数为1.5%。MET的分辨率从无DES的1.30增加到有1.5%氯化胆碱-D-果糖的2.61,从而实现基线分离。最后,对其分离效果和机理进行了推测。本研究建立的MET手性分离方法对于提高手性化合物的质量、保证临床药物的安全性和有效性具有重要意义。此外,它可能有助于研究和开发使用CD衍生物与DES的基于CE的手性分离技术。
The physical and chemical properties of chiral drugs are very similar. However, their pharmacological and toxicological effects vary significantly. For example, one enantiomer may have favorable properties whereas the other may be ineffective or even have toxic side effects. Hence, exploring innovative strategies to improve enantiomeric resolution is of great importance. Metoprolol (MET) is a β-receptor blocker used to treat hypertension, stable angina pectoris, and supraventricular tachyarrhythmia. Establishing chiral separation and analysis methods of MET enantiomers is important for enhancing the quality of chiral drugs. Capillary electrophoresis (CE) has the advantages of a small sample size, simple operation, high separation efficiency, and many alternative modes; therefore it is widely used in the field of chiral drug separation. The chiral selectors commonly used for CE-based chiral separation include cyclodextrin (CD) and its derivatives, polysaccharides, proteins, and macrocyclic antibiotics. CD is one of the most commonly used and effective chiral selectors for CE. The relatively hydrophobic structure inside the cavity and the relatively hydrophilic structure outside the cavity of CD enable it and chiral molecules to form inclusion compounds with different binding constants, thus achieving chiral separation. However, the use of CD alone as a chiral selector does not always yield satisfactory separation results. Hence, the addition of other additives, such as ionic liquids and deep eutectic solvents (DESs) to assist CD-based chiral separation systems has received extensive attention. Previous studies on the enantiomeric separation of MET by CE have focused on the addition of CD and its derivatives alone for separation. Few studies have been conducted on the synergistic addition of auxiliary additives to CD to improve the enantiomeric resolution of MET. In this study, three DESs, namely, choline chloride-D-glucose, choline chloride-D-fructose, and lactate-D-glucose, were used for the CE-based chiral separation of MET for the first time, and the synergistic effect of the DESs on the separation of MET enantiomers by CD-based capillary zone electrophoresis was speculated. For this purpose, an uncoated fused silica capillary with inner diameter of 50 μm, total length of 50 cm and effective length of 41.5 cm was used as the separation column. First, the effects of CD type, CD concentration, buffer pH, and buffer concentration on MET separation were investigated, and the optimal conditions (15 mmol/L carboxymethyl-β-cyclodextrin (CM-β-CD), pH=3.0, and 40 mmol/L phosphate buffer) were obtained. Other CE conditions were as follows: UV detection at 230 nm, applied voltage of 25 kV. All operations were carried out at 20 ℃. Next, three types of DESs were prepared as auxiliary additives via a mixed-heating method. The DESs were mixed in a 50 mL round-bottomed flask at a certain molar ratio and then heated in a water bath at 80 ℃ for 3 h until a clear and transparent liquid was obtained. The effects of different DESs and their mass fraction on chiral separation were subsequently studied. The optimal choline chloride-D-fructose mass fraction was ultimately determined to be 1.5%. The resolution of MET increased from 1.30 without DES to 2.61 with 1.5% choline chloride-D-fructose, thereby achieving baseline separation. Finally, the separation effect and mechanism were speculated. The MET chiral separation method established in this study is of great significance for improving the quality of chiral compounds and ensuring the safety and effectiveness of clinical drugs. Furthermore, it may be useful in the research and development of CE-based chiral separation techniques using CD derivatives with DESs.