High-performance liquid chromatographic separation and chiroptical properties of the enantiomers of naringenin and other flavanones

The HPLC enantiomeric separation of naringenin, eriodictyol, hesperetin and pinocembrin was accomplished in the normal-phase mode using two polysaccharide-derived chiral stationary phases (Chiralcel OD-H and Chiralpak AS-H) and various n-hexane/alcohol mobile phases. The 3′,4′ substituents pattern affect the enantioselectivity of these phases. Single enantiomers of naringenin were isolated by semipreparative HPLC and their CD spectra were measured and related to the absolute configuration by the exciton-coupling method. Online coupling HPLC/spectropolarimeter afforded the CD sign of the eluted peaks at a single wavelength, and the complete CD spectra of the eluted enantiomers were obtained by trapping them in the spectropolarimeter cell through a switching valve.