Encompassment of phthalyl sulfacetamide in α- and β-cyclodextrin using ultrasonication: Physicochemical and computational modeling investigations

Abstract

Phthalyl sulfacetamide (PSA) is an antibiotic sulfonamide. In this study, inclusion complexes (ICs) of α- (αCD) and β-cyclodextrin (βCD) were prepared in aqueous solution and in solid state with PSA using the ultrasonication (US) process. The structural and thermal characteristics of the US-assisted ICs were investigated by UV–Vis absorption, fluorescence, Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and computational modeling techniques. The improved dissolution of PSA in the presence of CD was confirmed by UV–Vis absorption. The experimental and computational modeling studies proved that the stoichiometry of the ICs was 1:1 for PSA/CD-ICs. It was also observed that the IC formation between βCD and PSA was the strongest when compared to αCD host. The enhanced thermal stability of PSA was achieved for PSA/CD-ICs when compared to pure form of PSA. FT-IR, 1H NMR and computational modeling studies indicated that biologically active sulfonamide group (ring-A) of PSA was encapsulated in the hydrophobic CD cavity. The stability of ICs in terms of energetic, thermodynamic and electronic properties was verified and the PSA/βCD-IC revealed higher stability compared to that of PSA/αCD-IC, as determined by PM3 method.