ß-Cyclodextrin inclusion complex to improve physicochemical properties of pipemidic acid: characterization and bioactivity evaluation.

The aptitude of cyclodextrins (CDs) to form host-guest complexes has prompted an increase in the development of new drug formulations. In this study, the inclusion complexes of pipemidic acid (HPPA), a therapeutic agent for urinary tract infections, with native ß-CD were prepared in solid state by kneading method and confirmed by FT-IR and 1H NMR. The inclusion complex formation was also characterized in aqueous solution at different pH via UV-Vis titration and phase solubility studies obtaining the stability constant. The 1:1 stoichiometry was established by a Job plot and the inclusion mechanism was clarified using docking experiments. Finally, the antibacterial activity of HPPA and its inclusion complex was tested on P. aeruginosa, E. coli and S. aureus to determine the respective EC50s and EC90s. The results showed that the antibacterial activity of HPPA:ß-CD against E. coli and S. aureus is higher than that of HPPA. Furthermore, HPPA and HPPA:ß-CD, tested on human hepatoblastoma HepG2 and MCF-7 cell lines by MTT assay, exhibited, for the first time, antitumor activities, and the complex revealed a higher activity than that of HPPA. The use of ß-CD allows an increase in the aqueous solubility of the drug, its bioavailability and then its bioactivity.

Physicochemical characterization and cytotoxic activity evaluation of hydroxymethylferrocene:ß-cyclodextrin inclusion complex.

An inclusion complex of hydroxymethylferrocene (FeMeOH) with ß-cyclodextrin (ß-CD) was prepared in the solid state by different techniques such as physical mixture, coprecipitation, kneading and freeze-drying. The formation of the inclusion complex was confirmed by X-ray Powder Diffractometry and Fourier Transform-Infrared spectroscopy. In aqueous solution, the 1:1 stoichiometry was established by a Job plot. The inclusion complex formation was also investigated by NMR and the stability constant (Kb) of the complex was determined to be 478 M⁻¹, which is in agreement with that obtained with UV-Vis tritation (Kb = 541.3 M⁻¹). The phase solubility study showed a diagram classified as Bs type and that the solubility of FeMeOH was slightly increased in the presence of ß-CD. Furthermore, utilizing phase solubility diagram data, the Kb was estimated to be equal to 528.0 M⁻¹. The cytotoxic activity of FeMeOH and its complexation product with ß-CD was determined using the MTT-assay on MDA-MB-231 cell line, showing that the inclusion complex has a higher capability of inhibiting cell growth compared to that of pure FeMeOH.