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Enantioseparation of analogs of the dipeptide alanyl-phenylalanine by capillary electrophoresis using neutral cyclodextrins as chiral selectors.
Metadata
Journaljournal of chromatography a4.049Date
2020 May 05
3 months ago
Publication Type
Journal Article
Volume
2020-Jul-19 / 1623 : 461158
Author
Konjaria ML 1, Scriba GKE 2
Affiliation
  • 2. Department of Pharmaceutical/Medicinal Chemistry, Friedrich Schiller University Jena, Philosophenweg 14, Jena, 07743, Germany. Electronic address: [email protected]
Doi
PMIDMESH
Cyclodextrins
Dipeptides
Electrophoresis, Capillary
Hydrogen-Ion Concentration
Stereoisomerism
Abstract
In the present study, the enantioseparation of the ll- and dd-enantiomers of the dipeptides Ala-Phe, Ala-phenylglycine (Phg), Ala-homoPhe, Ala-β-Phe, Gly-Phe and β-Ala-Phe was studied by capillary electrophoresis in the presence of native α-, β- and γ-cyclodextrin (CD) as well as their methyl and hydroxypropyl derivatives. Separations were performed under standardized conditions in fused-silica capillaries at pH 2.5, 3.5 and 9.5. All analyte enantiomers could be separated at acidic pH under at least one of the experimental conditions. β-CDs proved to be more universal chiral selectors than α- and γ-CDs. Only few alkaline conditions led to an enantioseparation. For a given dipeptide, the enantiomer migration order depended on the type of CD with regard to cavity size and degree of substitution. Little effect was found with regard to the structure of the dipeptides. pH-dependent reversal of the enantiomer migration order upon increasing the pH from 2.5 to 3.5 was observed for all dipeptides with at least one of the β-CD derivatives. In the case of β-CD, analysis of the complexation constants and the apparent limiting mobilities of the diastereomeric peptide enantiomer-CD complexes revealed, that the enantiomer migration order of Ala-Phe, Ala-homoPhe and Ala-β-Phe was determined by the stereoselective complexation by β-CD at pH 2.5. At pH 3.5 opposite chiral recognition of the enantiomers by β-CD was found for Ala-Phe and Ala-β-Phe resulting in the reversed migration order. In contrast, chiral recognition did not change in the case of Ala-homoPhe, but reversal of the enantiomer migration order was based on the apparent mobility of the diastereomeric analyte-CD complexes.
Keywords: Cyclodextrins Dipeptides Enantiomer migration order Enantioseparation
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J Chromatogr Ajournal of chromatography a
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