Modified mutagen activation in hepatic fractions from rats fed dietary rutin--interaction between gut flora and host metabolism.

Abstract Male Sprague-Dawley rats were fed a purified diet or one supplemented with the glycosidic plant flavonoid (+)rutin for 14 days. Rutin treatment significantly increased caecal bacterial β-glucosidase activity (responsible for the conversion of rutin to the flavonoid quercetin) and there was an associated increase in the capacity of hepatic fractions (S-9) to activate the food pyrolysis products IQ, MeIQ and MeIQx to bacterial mutagens in vitro . Hepatic conversion of aflatoxin B 1 to a mutagen was unaltered while in vitro activation of quercetin was significantly lower in tissue fractions from the rutin-fed rats compared with those from controls. Rutin treatment was without effect, however, on a number of hepatic cytochrome P -450-dependent mixed-function oxidase activities. The results suggest that products of bacterial metabolism of rutin formed in the hindgut may influence the activity of hepatic enzymes involved in the activation of certain classes of mutagen.