Enantiomeric Separation of Nefopam Hydrochloride by Affinity Electrokinetic Chromatography Using Chondroitin Sulfate A as Chiral Selector and Its Chiral Recognition Mechanism
In this study, a new approach to the enantioseparation of nefopam hydrochloride by means of affinity electrokinetic chromatography (AEKC) with chondroitin sulfate A belonging to linear ionic polysaccharides has been developed. The difference in the antinociceptive activity of the enantiomers of nefopam was demonstrated in some studies, and the method established in this paper allowed complete separation of nefopam. Especially, there are no reports concerned with the enantioselective separation of nefopam using chondroitin sulfate A as chiral selectors in CE. During the course of this work, both migration time and enantioseparation of nefopam were influenced by several parameters such as pH of the BGE, selector concentration, capillary temperature and applied voltage. Consequently, these parameters were systematically optimized in order to obtain the optimum enantioseparation of nefopam. Moreover, comparison of the influences of the studied parameters was further investigated using univariate analysis of variance as a calculation method by Statistical Product and Service Solutions (SPSS) in this paper. Finally, a mechanism of enantiorecognition in AEKC towards the enantiomers of nefopam with chondroitin sulfate A was described. KeywordsAffinity electrokinetic chromatography-Enantiomeric separation-Polysaccharides-Nefopam hydrochloride-Chondroitin sulfate A
- [Show abstract] [Hide abstract] ABSTRACT: Enantiomers (stereoisomers) can exhibit substantially different properties if present in chiral environments. Since chirality is a basic property of nature, the different behaviors of the individual enantiomers must be carefully studied and properly treated. Therefore, enantioselective separations are a very important part of separation science. To achieve the separation of enantiomers, an enantioselective environment must be created by the addition of a chiral selector to the separation system. Many chiral selectors have been designed and used in various fields, such as the analyses of drugs, food constituents and agrochemicals. The most popular have become the chiral selectors and/or chiral stationary phases that are of general use, i.e., are applicable in various separation systems and allow for chiral separation of structurally different compounds. This review covers the most important chiral selectors / chiral stationary phases described and applied in high performance liquid chromatography and capillary electrophoresis during the period of the last three years (2008–2011).
- [Show abstract] [Hide abstract] ABSTRACT: Several chiral reagents including cyclodextrins (CDs) and derivatives, crown ethers, proteins, chiral surfactants and polymers have been involved in dual selector systems for enantioseparation of a series of chiral compounds by capillary electrophoresis (CE). In comparison to the chiral reagents above-mentioned, there is no report concerning the use of polysaccharides in dual chiral CE system. In this paper we first investigate the enantioselectivity of polysaccharide-based dual selector systems towards some chiral drugs. During our recent work, glycogen belonging to the class of branched polysaccharides has been used as a novel chiral selector in CE. In this study, three glycogen-based dual chiral CE systems have been established for enantiomeric separations of several racemic basic drugs consisting of duloxetine, cetirizine, citalopram, sulconazole, laudanosine, amlodipine, propranolol, atenolol and nefopam. These three dual systems combined glycogen (neutral polysaccharide) with chondroitin sulfate A (CSA, ionic polysaccharide), β-CD and HP-β-CD, respectively. It was found that the dual system of glycogen/CSA exhibited good enantioselective properties toward the tested drugs. More importantly, compared to the single selector systems, synergistic effect was observed when glycogen was used with CSA for most of the analytes. This indicated the enhancement of enantioseparation observed for these analytes in glycogen/CSA system might be due to some favorable interaction effects between glycogen and CSA. Moreover, in order to evaluate the stereoselectivity of glycogen/CSA, the influences of buffer pH and selector concentration on enantioseparation of the studied drugs were also investigated.