Enantioseparation of erythro-mefloquine and its analogues in capillary electrophoresis

The enantioseparations of the chiral antimalaria drug (R,S)-erythro-alpha-(2-piperidyl)-2,8-bis(trifluoromethyl)4-quinolinemethanol (erythro-mefloquine, erythro-MQ) and its analogues were studied by capillary electrophoresis (CE) using cyclodextrins (CDs) as chiral selectors. The emphasis was put on the enantiomer affinity pattern of MQ towards different CDs as well as on simultaneous enantioseparations of erythro-MQ and its structural analogues. All three native CDs resolved the enantiomers of erythro-MQ and the enantiomer affinity pattern was the same, i.e. (+)-erythro-MQ was the more tightly bond enantiomer. However, the affinity pattern of erythro-MQ enantiomers was opposite in the case of heptakis-(2,3,6-tri-O-methyl)-beta-CD (TM-beta-CD), heptakis-(2,3-di-O-methyl-6-sulfo)-beta-CD (HDMS-beta-CD), heptakis-(3-O-methyl-2,6-di-O-sulfo)-beta-CD (HMdiSu-beta-CD) and randomly sulfated beta-CD (SU-beta-CD). Randomly hydroxyalkylated and acetylated derivatives of CDs appeared to be suitable chiral selectors for simultaneous enantioseparation of erythro-MQ and its analogues.