Pharmaceutical Properties of the Phloretin–4,4′-Bipyridine Cocrystal: Structure Analysis, Drug Release Profile, and Antioxidant Activity Research

To improve the water solubility of phloretin, we synthesized the Phl-4B cocrystal using the solvent evaporation method. Various analytical techniques including powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), ¹HNMR, and single-crystal X-ray diffraction (SCXRD) were employed to evaluate the crystal thermodynamics and structure. The results of PXRD and SCXRD showed that it was a new cocrystal crystallized in the P-1 space group of the triclinic system. Thermal analysis confirmed the purity of the Phl-4B cocrystal. The equilibrium solubility of the Phl-4B cocrystal in pH 1.2 was improved. In vitro simulated digestion experiments indicated that the release of the Phl-4B cocrystal followed Fick diffusion. The stability activity of phloretin after pharmaceutical cocrystallization was improved. The antioxidant of the Phl-4B cocrystal was better than that of pure Phl.