3-8-dihydroxy-6h-dibenzo(b-d)pyran-6-one and Geraniin

Different types of ellagitannins are reported to have various biological activities, such as antioxidant, antiviral, and antitumor activities. However, there are few definitive studies on the absorption and metabolism of ellagitannins. This review compares the absorption and metabolism of ellagitannins, and the antioxidant properties of their metabolites in rats, with those of intact ellagitannins by means of IN VITRO and IN VIVO assays. We isolated 7 urinary and intestinal microbial metabolites in rats after the ingestion of geraniin, which is a typical ellagitannin isolated from GERANIUM THUNBERGII, an antidiarrheic remedy in Japan. The structures of these metabolites were determined to be dibenzopyran derivatives ( 1- 7), using NMR and mass spectroscopic data. Four major metabolites ( 1- 4) prepared by chemical synthesis were evaluated for their antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl radical scavenging and oxygen radical absorbance capacity (ORAC) methods. The metabolites exhibited more potent antioxidant activities in the ORAC assay than intact ellagitannins, such as geraniin and corilagin. Furthermore, plasma ORAC scores increased with increases in the plasma concentration of the metabolites after the oral administration of geraniin to rats. These findings suggest that these metabolites may contribute to the health benefits of ellagitannins as antioxidants in the body.

Topics: Animals; Antioxidants; Biphenyl Compounds; Chromatography, High Pressure Liquid; Coumarins; Free Radical Scavengers; Geranium; Glucosides; Hydrolyzable Tannins; Intestinal Mucosa; Intestines; Magnetic Resonance Spectroscopy; Metabolic Networks and Pathways; Picrates; Pyrones; Rats

Urolithin A is a major metabolite produced by rats and humans after consumption of pomegranate juice or pure ellagitannin geraniin. In this study, we investigated the anti-inflammatory effect of urolithin A on carrageenan-induced paw edema in mice. The volume of paw edema was reduced at 1h after oral administration of urolithin A. In addition, plasma in treated mice exhibited significant oxygen radical antioxidant capacity (ORAC) scores with high plasma levels of the unconjugated form at 1h after oral administration of urolithin A. These results indicate strong associations among plasma urolithin A levels, the plasma ORAC scores, and anti-inflammatory effects and may help explain a mechanism by which ellagitannins confer protection against inflammatory diseases.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antioxidants; Coumarins; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Discovery; Drug Evaluation, Preclinical; Edema; Free Radical Scavengers; Glucosides; Glucuronides; Humans; Hydrolyzable Tannins; Lythraceae; Mice; Mice, Inbred ICR; Rats