Development and validation of a separation method for the diastereomers and enantiomers of aziridine-type protease inhibitors

Aziridine derivatives are attracting pharmacological interest as protease inhibitors. Due to their two centers of chirality, the aziriclines studied here are mixtures of two diastereomers and corresponding enantiomers. Applying cycloclextrin-modified capillary electrophoresis resulted in a baseline separation of the four isomers. The most robust separation was obtained by means of 2 mm sulfated beta-cyclodextrin in 50 mm phosphate buffer of pH 2.5. Using this method, 0.25% of the trans-diastereomers aziridine could be precisely and accurately quantified in the presence of 99.75% of the cis-isomers. The corrected peak-area ratios, migration times, and resolutions were found to be robust with respect to small variations of voltage, buffer concentrations, pH, temperature, chiral selector concentration, and different lots.