Quantification of flumequine enantiomers in plasma by high-performance liquid chromatography

Enantiomeric profiling of quinolones and quinolones resistance gene qnrS in European wastewaters

Wastewater-based epidemiology (WBE) was applied for the first time in seven cities across Europe with the aim of estimating quinolones consumption via the analysis of human urinary metabolites in wastewater. This report is also the first pan-European study focussed on the enantiomeric profiling of chiral quinolones in wastewater. By considering loads of (fluoro)quinolones in wastewater within the context of human stereoselective metabolism, we identified cities in Southern Europe characterised by both high usage and direct disposal of unused ofloxacin. In Northern European cities, S-(-)-ofloxacin loads were predominant with respect to R-(+)-ofloxacin. Much more potent, enantiomerically pure S-(-)-ofloxacin was detected in wastewaters from Southern European cities, reflecting consumption of the enantiomerically pure antibiotic. Nalidixic acid, norfloxacin and lomefloxacin were detected in wastewater even though they were not prescribed according to official prescription data. S,S-(-)-moxifloxacin and S,S-(-)-moxifloxacin-N-sulphate were detected in wastewater due to metabolism of moxifloxacin. For the first time, average population-normalised ulifloxacin loads of 22.3 and 1.5 mg day^-1 1000 people^-1 were reported for Milan and Castellón as a result of prulifloxacin metabolism. Enrichment of flumequine with first-eluting enantiomer in all the samples indicated animal metabolism rather than its direct disposal. Fluoroquinolone loads were compared with qnrS gene encoding quinolone resistance to correlate usage of fluoroquinolone and prevalence of resistance. The highest daily loads of the qnrS gene in Milan corresponded with the highest total quinolone load in Milan proving the hypothesis that higher usage of quinolones is linked with higher prevalence of quinolone resistance genes. Utrecht, with the lowest quinolones usage (low daily loads) had also one of the lowest daily loads of the qnrS gene. However, a similar trend was not observed in Oslo nor Bristol where higher qnrS gene loads were observed despite low quinolone usage.

Biotransformation of flumequine by the fungus Cunninghamella elegans

The metabolism of the antibacterial fluoroquinolone drug flumequine by Cunninghamella elegans was investigated using cultures grown in Sabouraud dextrose broth with 308microM flumequine. The cultures were extracted with ethyl acetate; metabolites were separated by high-performance liquid chromatography and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Flumequine was transformed to two diastereomers of 7-hydroxyflumequine (23 and 43% of the total chromatographic peak area at 280nm) and 7-oxoflumequine (11% of the total peak area). This is the first time that the two 7-hydroxy diastereomers have been characterized structurally; the hydroxyflumequines are known to have less antimicrobial activity than flumequine.

Recent applications of stereoselective chromatography

Some recent applications of stereoselective chromatography in the fields of clinical pharmacy, drug analysis, food, and natural products are reviewed. The review is documented with up-to-date literature, which will assist further expansion of research in these areas.