The small intestine can both absorb and glucuronidate luminal flavonoids

We have studied the perfusion of the jejunum and ileum in an isolated rat i ntestine model with flavonoids and hydroxycinnamates and the influence of g lycosylation on the subsequent metabolism. Flavone and flavonol glucosides and their corresponding aglycones are glucuronidated during transfer across the rat jejunum and ileum and this glucuronidation occurs without the need for gut microflora. Furthermore, this suggests the presence of glycosidase s as well as UDP-glucuronyl transferase in the jejunum. In contrast, querce tin-3-glucoside and rutin are mainly absorbed unmetabolised. The results su ggest that the more highly reducing phenolics are absorbed predominantly as glucuronides (96.5%+/-4.6) of the amount absorbed, whereas monophenolic hy droxycinnamates and monophenolic B-ring flavonoids are less predisposed to glucuronidation and higher levels of aglycone (88.1%+/-10.1) are detected o n absorption through both the jejunum and ileum. (C) 1999 Federation of Eur opean Biochemical Societies.