Research Progress of Bound Polyphenols in Improving Intestinal Oxidative Stress and Intestinal Barrier

Food is abundant in phenolic compounds and phenols are perceived as a rich source of natural antioxidants and vital functional factors. Bound polyphenols are a form of phenolic compounds that exist in the residue from which free polyphenols have been extracted and are combined with other substances through ester bonds, glycosidic bonds, ether glycosidic bonds, etc. As the forefront of human immune defense, the intestine is prone to exogenous and metabolic oxygen radical damage, which triggers intestinal oxidative stress. Intestinal oxidative stress can disrupt the tight junctions between intestinal epithelial cells through various pathways, leading to intestinal epithelial barrier functional impairment and increasing intestinal permeability, which can induce various diseases. Bound polyphenols, as a natural antioxidant, have structural integrity and activity stability in the intestine. These components feature an ameliorative effect on intestinal oxidative stress as well as impaired intestinal barrier function by modulating immune function and regulating the expression of inflammatory factors, antioxidant enzymes and barrier proteins.