New insight into the discrimination between omeprazole enantiomers by cyclodextrins in aqueous solution

We report results regarding the use of 1H-NMR spectroscopy in the study of the conformational behaviour and optical activity of omeprazole. Changes in the chemical shifts of chosen atoms reveal that the conformational behaviour of omeprazole is temperature and pH sensitive. Separation and identification of omeprazole enantiomers in the presence of natural and derivative cyclodextrins, such as ß-cyclodextrin (ßCD) and methyl-ß-cyclodextrin (MßCD) are achieved using 1H-NMR spectroscopy, with information from molecular dynamics simulation. This work shows that ßCD includes preferentially R-(–)-omeprazole, acting as a chiral selector. This discrimination of omeprazole enantiomers by cyclodextrins allows development of pharmaceutical formulations with a better bioavailability profile