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Updated: Nov 10, 2025
Transport Properties of Ibuprofen Encapsulated in Cyclodextrin Nanosponge Hydrogels: A Proton HR-MAS NMR Spectroscopy Study
Published on: August 15, 2016
A physicochemical, thermodynamical, structural and computational evaluation of kynurenic acid/cyclodextrin complexes
Adrián Matencio1, Fabrizio Caldera1, Alberto Rubin Pedrazzo1
1Dip. Di Chimica, Università di Torino, via P. Giuria 7, 10125 Torino, Italy.
Kynurenic acid (KYNA) forms inclusion complexes with cyclodextrins (CDs), with HPβ-CD showing the strongest binding. Complexation is influenced by pH and temperature, with thermodynamic studies revealing a spontaneous process.
Area of Science:
- Supramolecular Chemistry
- Medicinal Chemistry
- Physical Chemistry
Background:
- Kynurenic acid (KYNA) is an endogenous NMDA receptor antagonist with potential therapeutic applications.
- Cyclodextrins (CDs) are widely used as host molecules to improve the solubility and bioavailability of guest compounds.
- Understanding the complexation behavior of KYNA with CDs is crucial for its pharmaceutical development.
Purpose of the Study:
- To investigate the complexation interactions between Kynurenic acid (KYNA) and various natural and modified cyclodextrins (CDs).
- To determine the binding constants and thermodynamic parameters of these inclusion complexes.
- To elucidate the influence of environmental factors like pH and temperature on the complexation process.
Main Methods:
- Spectrophotometric titration was employed to determine complexation constants (KF).
- Studies were conducted across a range of pH and temperatures to assess environmental influences.
- Fourier Transform Infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA) were used for characterization.
- Molecular docking simulations were performed to understand interaction mechanisms.
Main Results:
- Hydroxypropyl-β-cyclodextrin (HPβ-CD) exhibited the highest complexation constant (270.94 ± 29.80 M-1) with KYNA.
- Among natural CDs, β-cyclodextrin showed the most efficient complexation with KYNA.
- Complexation efficacy decreased significantly at higher pH values (above pKa) and with increasing temperature.
- Thermodynamic analysis indicated a spontaneous, entropy- and enthalpy-driven complexation process at 25 °C.
Conclusions:
- HPβ-CD is a highly effective host for Kynurenic acid complexation.
- The inclusion complex formation is sensitive to pH and temperature, requiring careful control for optimal application.
- FTIR, TGA, and molecular docking confirm the formation and provide insights into the binding interactions of KYNA-CD complexes.
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