Caffeine-Cyclodextrin Complexes as Solids: Synthesis, Biological and Physicochemical Characterization

Area of Science:

• Supramolecular Chemistry
• Toxicology
• Materials Science

Background:

• Caffeine-cyclodextrin complexes are investigated for various applications.
• Understanding the formation and properties of these inclusion complexes is crucial.
• Cyclodextrins are known to modify the physical and chemical properties of guest molecules.

Purpose of the Study:

• To optimize the synthesis of caffeine complexes with alpha-, beta-, and gamma-cyclodextrins.
• To characterize the formed complexes and understand their formation mechanism.
• To evaluate the toxicity of these complexes in zebrafish embryos.

Main Methods:

• Mechanochemical and in-solution synthesis methods were optimized.
• Powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), FT-IR, and Raman spectroscopy were used for characterization.
• Molecular modeling was employed to understand guest-host interactions.
• Zebrafish embryo toxicity assays and HPLC were performed.

Main Results:

• Short-duration, low-energy cogrinding and evaporation proved effective for complex formation.
• Characterization confirmed the formation of caffeine-cyclodextrin complexes.
• The complexes exhibited significantly higher toxicity in zebrafish embryos compared to pure caffeine or cyclodextrins.
• HPLC analysis indicated similar caffeine concentrations in embryos irrespective of the administered form.

Conclusions:

• Optimized mechanochemical methods provide efficient routes for caffeine-cyclodextrin complex synthesis.
• The observed high cytotoxicity of the complexes in zebrafish embryos is likely due to a synergistic effect between caffeine and cyclodextrins.
• This finding highlights the importance of evaluating the toxicological profile of supramolecular complexes.