A physicochemical, thermodynamical, structural and computational evaluation of kynurenic acid/cyclodextrin complexes

In this work, the interaction between Kynurenic acid (KYNA) and several natural and modified cyclodextrins (CDs) is carried out. Among all the CD tested, HP beta-CD showed the strongest complexation constant (K-F), with a value of 270.94 +/- 29.80 M-1. Between natural (alpha- and beta-) CDs, the complex of KYNA with beta-CD was the most efficient. The inclusion complex of KYNA with CDs showed a strong influence of pH and temperature. The K-F value decreased at high pH values, when the pK(a) was passed. Moreover, an increase of the temperature caused a decrease in the K-F values. The thermodynamic parameters of the complexation (Delta H degrees, Delta S degrees and Delta G degrees) were studied with negative entropy, enthalpy and spontaneity of the process at 25 degrees C. Moreover, the inclusion complex was also characterized using FTIR and TGA. Finally, molecular docking calculations provided different interactions and their influence in the complexation constant.

Automated summary

In this study, the interaction between Kynurenic acid (KYNA) and various cyclodextrins (CDs) was investigated, with HP beta-CD demonstrating the strongest complexation constant. The formation of inclusion complexes was found to be influenced by pH and temperature, with thermodynamic parameters and molecular docking calculations providing insights into the complexation mechanism.