Chiral recognition of imperanene enantiomers by various cyclodextrins: a capillary electrophoresis and NMR spectroscopy study.
The enantiomers of imperanene, a novel polyphenolic compound of Imperata cylindrica (L.), were separated via cyclodextrin-modified capillary electrophoresis. The anionic form of the analyte at pH 9.0 was subject to complexation and enantioseparation CE studies with neutral and charged cyclodextrins. As chiral selectors 27 CDs were applied differing in cavity size, sidechain, degree of substitution (DS) and charge. Three hydroxypropylated and three sulfoalkylated CD preparations provided enantioseparation and the migration order was successfully interpreted in each case in terms of complex mobilities and stability constants. The best enantioresolution (R(S)  = 1.26) was achieved using sulfobutyl-ether-γ-CD (DS ∼4), but it could be enhanced by extensive investigations on dual selector systems. After optimization (CD concentrations and pH) R(S)  = 4.47 was achieved using a 12.5 mM sulfobutyl-ether-γ-CD and 10 mM 6-monodeoxy-6-mono-(3-hydroxy)-propylamino-β-cyclodextrin dual system. The average stoichiometry of the complex was determined with Job's method using NMR-titration and resulted in a 1:1 complex for both (2-hydroxy)propyl-β- and sulfobutyl-ether-γ-CD. Further NMR experiments suggest that the coniferyl moiety of imperanene is involved in the host-guest interaction.
Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, Hungary; Cyclolab Ltd., Budapest, Hungary.
Tamás
T
Sohajda
Zoltán
Z
Szakács
Lajos
L
Szente
Béla
B
Noszál
Szabolcs
S
Béni
D003505:Cyclodextrins / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D017711:Nonlinear Dynamics; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010636:Phenols / Q000032:analysis / Q000737:chemistry*; D013237:Stereoisomerism
D003505:Cyclodextrins; D010636:Phenols; C093767:imperanene