Characterization and In Vitro Prebiotic Activity of Pterostilbene/β-Cyclodextrin Inclusion Complexes

Pterostilbene (PTS) has multiple benefits, but poor water solubility and bioavailability limit its application. PTS/β-CD inclusion complexes were synthesized through the phase solubility method to enhance their water solubility. The inclusion complexes were characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance, and molecular docking techniques. The results demonstrated that PTS and β-CD successfully created inclusion complexes with a host-guest ratio of 1:1 and a stability constant of 166.7 M^-1. To further investigate its prebiotic function, simulated digestion experiments revealed that β-CD exhibited resistance to digestion, allowing it to reach the colon intact. During gastrointestinal digestion, PTS in the PTS/β-CD inclusion complexes was gradually released. Following digestion, the in vitro fermentation of healthy human feces further confirmed the probiotic properties. Compared to the β-CD and fructooligosaccharide (FOS) groups, the PTS/β-CD group significantly increased the production of acetic acid, butyric acid, and lactic acid, respectively. Additionally, beneficial bacteria, such as Bifidobacterium and Lactobacillus, proliferated in the PTS/β-CD group, while the relative abundance of potential pathogenic bacteria, such as Lactococcus, Streptococcus, and Klebsiella, was significantly reduced. Compared to the blank group, propionic acid and butyric acid concentrations in the β-CD group were significantly higher. The abundance of Lactobacillus and other key bacterial species in the β-CD group increased, while the relative abundance of Klebsiella and other pathogens decreased significantly. In conclusion, PTS/β-CD inclusion complexes altered the composition of intestinal flora, promoting the proliferation of beneficial bacteria and inhibiting the growth of harmful bacteria, thereby demonstrating dual probiotic functionality.