Investigation on the chiral recognition site of enantioselective separation of ofloxacin by capillary zone electrophoresis using vancomycin as a chiral selector / 药学学报

ABSTRACT

The chiral recognition site of the macrocyclic antibiotic vancomycin, used as a chiral selector in capillary electrophoresis (CE), was studied with ofloxacin, antofloxacin (a new fluoroquinolone antibiotic under development) and R-antofloxacin, as well as with norvancomycin. Enantioselectivity of vancomycin and norvancomycin was compared. The influence of vancomycin concentration, pH of buffer, and separation voltage in CE were examined in order to investigate interactions between enantiomers and vancomycin. Furthermore, interactions of chiral selectors and enantiomers were calculated by molecular mechanics method with Chem 3D software. The result indicates that both vancomycin and norvancomycin have two domains in 3D structure, and the domain I of vancomycin was considered to be the chiral recognition site of ofloxacin. The degree of interaction between vancomycin and ofloxacin is determined as follows hydrogen bond occurring with carboxylic group at C-6 of ofloxacin and hydroxyl group of sugar part of vancomycin, the matching degree of molecular sizes of ofloxacin with the pocket in domain I of vancomycin and the hydrophobic interaction between methyl group at C-10 of piperidine group of ofloxacin and N-methyl leucine of vancomycin.