Determination of the structure of quinolone-gamma-cyclodextrin complexes and their binding constants by means of UV-Vis and H-1 NMR

作者：Leyva Elisa; Moctezuma Edgar; Loredo Carrillo Silvia E; Espinosa Gonzalez Claudia G; Cardenas Chaparro Agobardo

来源：Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2018, 91(3-4): 211-218.

DOI：10.1007/s10847-018-0817-x

• Nalidixic acid
• Oxolinic acid
• Cyclodextrin
• Inclusion complex
• Quinolones

The host-guest inclusion complex structure and binding ability of two different quinolones with gamma-cyclodextrin (gamma-CD) were investigated in solution by means of UV-Vis and H-1 NMR spectroscopy. Competition of oxolinic and nalidixic acid molecules for the gamma-CD cavity was evaluated by determination of association constants. Both quinolones form 1:1 inclusion complexes, their binding constants at room temperature (25 A degrees C) under acidic and basic conditions were calculated using Benesi-Hildebrand equation. The stability of the complexes was dependent on the structure of the quinolone. In general, the weaker binding constants were observed for oxolinic acid-gamma-CD complexes (1616 and 1765 M-1) and the larger binding constants were obtained for nalidixic acid-gamma-CD complexes (3760 and 3840 M-1). H-1 NMR studies in D2O were performed to elucidate the structure of each inclusion complex, nalidixic acid molecule penetrates more deeply into the gamma-CD cavity and an intermolecular hydrogen bond is formed. Knowledge about structure and relative stability of quinolone-gamma-CD complexes will be useful for future applications of these antimicrobial agents in medicinal chemistry.

• 出版日期2018-8