Preparation and in Vitro Prebiotic Activity of Kaempferol/β-Cyclodextrin Inclusion Complexes

To improve the water solubility and bioavailability of kaempferol (KAE) and enhance its regulatory effect on gut microbiota as a probiotic-related agent, β-cyclodextrin/kaempferol (β-CD/KAE) inclusion complexes were prepared using the stirring solution method. The stability constant was determined using the solubility method, and various techniques including Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance, and molecular docking were used for systematic characterization of the inclusion complexes. Furthermore, its antioxidant capacity and stability were assessed, along with evaluations of its probiotic potential through in vitro simulated digestion and fecal fermentation experiments. The results showed that β-CD formed the stable inclusion complexes with KAE at a 1:1 molar ratio (Kc=3852 L/moL), significantly enhancing KAE's water solubility as well as its stability against light, heat, and digestive environments (P<0.05). In vitro digestion experiments, the β-CD/KAE inclusion complexes remained stable during gastrointestinal digestion, showing no significant changes in total sugar or reducing sugar content (P>0.05) and reaching the colon intact. In vitro fermentation revealed that the β-CD/KAE inclusion complexes significantly promoted the production of short-chain fatty acids and lactic acid, while lowering pH levels to stimulate the growth of beneficial bacteria, thus demonstrating good prebiotic activity. In conclusion, the β-CD/KAE inclusion complexes not only improve KAE's physicochemical properties but also exhibit considerable probiotic potential by modulating gut microbiota composition and promoting beneficial metabolite generation. It holds important application value in the fields of medicine and health.