Enantioseparation of hydroxyeicosatetraenoic acids by hydroxypropyl-γ-cyclodextrin-modified micellar electrokinetic chromatography

Complete resolution of hydroxyeicosatetraenoic acid (HETE) enantiomers was achieved using hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD)-modified MEKC. The optimum running conditions were determined to be utilizing a 30 mM phosphate-15 mM borate buffer (pH 9.0) containing 30 mM HP-gamma-CD and 75 mM SDS as the BGE, application of +30 kV as the effective voltage, and carrying out the experiment at 15 degrees C. The eluents were detected at 235 nm. The method was used successfully for the simultaneous separations of (S)- and (R)-enantiomers of regioisomeric 8-, 11-, 12-, and 15-HETEs. Subsequently, the optimized method was applied to evaluate the stereochemistry of 8- and 12-HETEs from the marine red algae, Gracilaria vermiculophylla and Gracilaria arcuata, respectively. The 8-HETE was found to be a mixture of 98% (R)-enantiomer and 2% (S)-enantiomer, while the 12-HETE was a mixture of 98% (S)-enantiomer and 2% (R)-enantiomer. The present study demonstrates that the HP-gamma-CD-modified MEKC method is simple and sensitive and provides unambiguous information on the configuration of natural and synthetic HETEs.