Determination of enantio‐separation, absolute configuration and chiral recognition mechanism of ofloxacin and flumequine by HPLC and modeling studies

Abstract

AbstractBACKGROUNDThe determination of enantio‐separation, absolute configuration and chiral recognition mechanism of ofloxacin and flumequine was carried out by high‐performance liquid chromatography (HPLC) and modeling studies. The column used was a Chiralcel OD‐H with normal and polar organic mobile phase modes. The exhaustive chiral separation was optimized through various HPLC parameters.RESULTSThe selectivity, separation factors and resolution factors for ofloxacin were 8.2 and 9.4, 1.15 and 2.43 in the normal mobile phase, while these values were 10.5 and 12.0, 1.14 and 2.40 for flumequine in polar organic mobile phase mode, respectively. The thermodynamic parameters were ΔH (−0.137 J mol−1), ΔS (7.35 × 10−4 J mol−1) and ΔG (−0.360 J mol−1 K−1) for ofloxacin, and ΔH (−0.035 J.mol−1), ΔS (21.3 × 10−4 J mol−1) and ΔG (−0.105 J mol−1 K−1) for flumequine, confirming spontaneous chiral separation at all temperatures. The chiral recognition mechanism was established by HPLC and modeling results. The modeling binding affinity were −2.5 kcal mol–1 (R‐enantiomer) and −2.6 kcal mol–1 (S‐enantiomer) for ofloxacin, and −2.30 kcal mol–1 (R‐enantiomer) and −2.40 kcal mol–1 (S‐enantiomer) for flumequine enantiomers. The chiral resolution is controlled by hydrogen bonding, π–π interactions and other forces.CONCLUSIONThese methods were applied to monitor ofloxacin and flumequine quinolones in urine samples. Briefly, the developed chiral HPLC methods are effective and may be used to analyze the reported enantiomers in any biological sample. © 2021 Society of Chemical Industry (SCI).