The separation of the enantiomers of chlorofeniramine using cyclodextrins as a chiral selectors

Author: Natia Tsertsvadze
Co-authors: Ana Gogolashvili, Nino megeneishvili, Davit Khutsishvili
Keywords: Capillary electrophoresis, chiral, enantiomers, cyclodextrons
Annotation:

Annotation The existences of asymmetric molecules have long been known. Almost half of the drugs currently used in therapy have a chiral center in their molecule. of Currently, the major part of chiral drugs are marketed/sold as racemates, consisting of an equimolar mixture of two enantiomers. Although the enantiomers have the same chemical connectivity of atoms, they exhibit marked differences in their pharmacology, toxicology, parmacokinetics, metabolism, etc. The enantiomers differ in their interactions with enzymes, proteins and receptors. These differences in interactions lead to differences in the biological activities. The understanding of the enantioselectivity of drug action sites is continually evolving, consequently the tendency of marketing pure enantiomers of chiral drugs increases. With this tendency the development of new improved methods for the separation and determination of enantiomers became a permanent necessity and also a challenge. Capillary electrophoresis (CE), which is beginning to play a major role in the separation of chiral compounds, being considered often superior to high performance liquid chromatography (HPLC), accepted as the most universally applied method in pharmaceutical analyses (es inglisuri enistvis yalian gryeli zinadadeba aris, magram motmena sheizleba). The advantages of using CE in chiral separations are related to its high resolving power, relatively short analysis time, rapid method development, low consumption of solvent, sample and chiral selector and especially with the high flexibilty of choosing and changing the chiral selector. Another big advantage is that in CE, direct chiral separation is typically carried out by simply dissolving an enantiomerically pure additive in the buffer solution. Enantioseparation can be achieved only using chiral selectors. Cyclodextrins (CDs) are the important and frequently used class of chiral selectors in CE, as they are nontoxic and multimodal selectors since multiple chiral interactions are possible by very different stereoselective mechanisms. Using CDs are very convenient due to their solubility in aqueous solutions. In process of enantioseparation, cyclodextrins discriminate between the enantiomers by an enantioselective complexation of the analyte and the chiral selector, giving rise to differences in the electrophoretic mobilities of the enantiomers. The differences between them are the result of different effective charge densities, which is caused by different spatial orientations or specific intermolecular interactions.