γ-Cyclodextrin metal–organic framework enhanced the bioavailability of vitexin in rats by increasing solubility and inhibiting re-crystallization

Abstract

γ-Cyclodextrin metal–organic frameworks (γ-CD-MOFs) were prepared using γ-CD and KOH as the raw materials. The γ-CD-MOFs showed a cubic shape with a particle size in the range of 400–700 nm and a Langmuir surface area of 406.88 m² g⁻¹. The γ-CD-MOFs were used as a carrier of vitexin through adsorption in methanol, and the loading capacity was 34.9 mg g⁻¹. XRD showed that vitexin lost its crystal structure, and FTIR showed that vitexin had secondary interactions with the carrier. The structure of the γ-CD-MOFs collapsed quickly in water, thereby rapidly releasing the loaded vitexin. Using the carrier, the water solubility of vitexin increased by about 18.3 times from 31.79 μg mL⁻¹ to 581.78 μg mL⁻¹ in simulated gastric fluid at 37 °C. Meanwhile, the presence of γ-CD inhibited the re-crystallization of vitexin and maintained its supersaturated status through the formation of complexes. A pharmacokinetic study showed that the oral bioavailability of vitexin was enhanced by 1.99 times in rats through the γ-CD-MOF carrier.