Preparation of β-cyclodextrin and hydroxypropyl-β-cyclodextrin inclusion complexes of baicalein and evaluation of their effects on dextran sulfate sodium-induced acute ulcerative colitis in mice

β-cyclodextrin and hydroxypropyl-β-cyclodextrin were combined with baicalein to improve its solubility in water. The physicochemical properties and pharmacokinetic characteristics of the two complexes and their therapeutic effects on dextran sulfate sodium-induced ulcerative colitis were studied in mice. Differential scanning calorimetry, X-ray diffraction, infrared spectroscopy, and scanning electron microscopy showed that the two complexes were successfully prepared and significantly improved baicalein's solubility and dissolution. The t1/2, Cmax, and AUC0-∞ values of the inclusion complexes were substantially better than those of the original drug in rats. Analysis of the tissue distribution of acute ulcerative colitis in mice showed that the peak concentrations of baicalein and its metabolite, baicalin, in the small intestines, liver, and colon were higher than that of the free drug. The therapeutic effect of the inclusion compound was significantly better than that of the original drug. This study provides a new reference for applying cyclodextrin inclusion complex in ulcerative colitis.