Intestinal bacterial metabolism of rutin and its relation to mutagenesis

After rutin (50-1500 mg/kg) was administered orally to rats, the relationship between its metabolites and mutagenicity was investigated. Quercetin conjugates were detected in the urine of rats treated with more than 150 mg/kg. Administration of rutin less than 100 mg/kg resulted in phenolic acid-like metabolites. However, intact rutin was not detected in the urine of rats treated with different amounts. When rutin was cultured with human intestinal bacteria, the amount of quercetin was increased gradually with a corresponding decrease in the level of rutin and then quercetin was decreased gradually with a corresponding increase in the level of unidentified compounds. The ring fission bacterium of quercetin was Pediococcus Q-05. These results suggest that rutin could be metabolized and transformed from mutagenic to nonmutagenic by intestinal bacteria in human intestine.