Stereoisomeric Separation of Flavanones and Flavanone-7-O-glycosides by Capillary Electrophoresis and Determination of Interconversion Barriers

• Published in: Analytical chemistry (Washington) Vol. 78; no. 10; pp. 3424 - 3433
• Main Authors: Wistuba, Dorothee, Trapp, Oliver, Gel-Moreto, Nuria, Galensa, Rudolf, Schurig, Volker
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.05.2006
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Computer simulation; Cyclodextrins - chemistry; Electrolytes; Electrophoresis, Capillary - methods; Exact sciences and technology; Flavanones - analysis; Flavanones - chemistry; Glycosides - chemistry; Hydrogen-Ion Concentration; Molecular Structure; Organic chemicals; Other chromatographic methods; Stereoisomerism; Surfactants; Background concentration; Elution; Capillary electrophoresis; Micellar electrokinetic capillary chromatography; Activation parameter; Sodium compound; Buffer system; Surfactant; Lauryl sulfate; Cyclodextrin; Chemical modification; Simulation; Alternative method; Glycoside; Software; Rate constant
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac0600499

The stereoisomeric separation of several flavanones and flavanone-7-O-glycosides has been achieved with capillary electrophoresis by adding native cyclodextrins or cyclodextrin derivatives to the background electrolyte. As an alternative method, micellar electrokinetic chromatography with sodium cholate as a chiral surfactant has been used for the epimeric separation of two flavanone-7-O-glycosides. The effect of buffer systems containing mixtures of cyclodextrin with either sodium dodecyl sulfate or sodium cholate upon the chiral recognition of flavanones and flavanone-7-O-glycosides as well as the variation of the background electrolyte (concentration of buffer and surfactant, pH value, organic modifier), and its influence on the resolution factor R s was investigated. Temperature- and pH-dependent enantiomerization or epimerization barriers of several flavanones (naringenin, homoeriodictyol) and flavanone-7-O-glycosides (naringin, neohesperidin, prunin, narirutin) in basic media (pH values of 9−11) have been observed. Interconversion profiles featuring characteristic plateau formation of the elution pattern were observed at high pH and evaluated with the simulation software ChromWin to determine rate constants k(T) and Eyring activation parameters, ΔG #(T), ΔH #, and ΔS #.