The relative contribution of the small and large intestine to the absorption and metabolism of rutin in man

Tomato juice containing rutin (quercetin-3-rutinoside) was ingested by healthy volunteers and ileostomists. Blood and urine collected over 24 h were analysed by HPLC with photodiode array (PDA) and tandem mass spectrometric detection. Low concentrations of isorhamnetin-3-glucuronide (C_max = 4.3 ± 1.5 nmoles/l) and quercetin-3-glucuronide (C_max = 12 ± 2 nmoles/l) were detected in plasma of healthy subjects. Metabolites appeared in blood after 4 h indicating absorption from the large intestine. Nine metabolites of rutin were detected in urine but with considerable variation in total amount (40 ± 1-4981 ± 115 nmoles over 24 h). No metabolites were detected in plasma or urine of ileostomists and 86 ± 3% of the ingested rutin was recovered in ileal fluid. In subjects with an intact large intestine, but not ileostomists, rutin was catabolised with the appearance of 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylacetic acid and 3-hydroxyphenylacetic acid in urine accounting for 22% of rutin intake.