Urolithins Display both Antioxidant and Pro-oxidant Activities Depending on Assay System and Conditions

Citations Over TimeTop 10% of 2013 papers

Abstract

The biological effects of polyphenolic ellagitannins are mediated by their intestinal metabolites, urolithins. This study investigated redox properties of urolithins A and B using ORAC assay, three cell-based assays, copper-initiated pro-oxidant activity (CIPA) assay, and cyclic voltammetry. Urolithins were strong antioxidants in the ORAC assay, but mostly pro-oxidants in cell-based assays, although urolithin A was an antioxidant in cell culture medium. Parent compound ellagic acid was a strong extracellular antioxidant, but showed no response in the intracellular assay. The CIPA assay confirmed the pro-oxidant activity of ellagitannin metabolites. In the cell proliferation assay, urolithins but not ellagic acid decreased growth and metabolism of HepG2 liver cells. In cyclic voltammetry, the oxidation of urolithin A was partly reversible, but that of urolithin B was irreversible. These results illustrate how strongly measured redox properties depend on the employed assay system and conditions and emphasize the importance of studying pro-oxidant and antioxidant activities in parallel.

Related Papers

• → Tea Is a Significant Dietary Source of Ellagitannins and Ellagic Acid(2018)64 cited
• → Raspberry marc extracts increase antioxidative potential, ellagic acid, ellagitannin and anthocyanin concentrations in fruit purees(2015)56 cited
• → Ellagitannins from Portuguese oak wood (Quercus pyrenaica Willd.) used in cooperage: influence of geographical origin, coarseness of the grain and toasting level(2007)53 cited
• → Health-enhancing activity of ellagic acid and ellagitannin of selected species from the genus Rubus – Review(2018)1 cited
• → Bioavailability, Metabolism, and Bioactivity of Food Ellagic Acid and Related Polyphenols(2008)14 cited