Abstract: Ellagic acid (EA), a natural antioxidant, is a polyphenolic compound found in fruits, nuts, and vegetables. EA can be metabolized by gut bacteria to urolithins. EA has very poor intestinal bioavailability, while urolithins can be more easily absorbed than EA and hence can be considered as the material basis for the antioxidant activity of EA. Various animal and clinical studies indicate that EA and urolithins can improve the intestinal microbial flora, promote intestinal health, and prevent the occurrence and development of intestinal diseases. The bioactivities of EA and urolithins mainly include antioxidation, anti-inflammation, and regulating the intestinal flora. The present paper reviews the chemical structures, metabolic pathways and bioactivities of EA and urolithins and their applications in research on intestinal diseases.

Key words: ellagic acid; urolithins; antioxidation; anti-inflammation; microbiome