INTESTINAL-ABSORPTION OF LUTEOLIN AND LUTEOLIN 7-O-BETA-GLUCOSIDE IN RATS AND HUMANS

In this study, we investigated the intestinal absorption of luteolin a nd luteolin 7-O-beta-glucoside in rats by HPLC. The absorption analysi s using rat everted small intestine demonstrated that luteolin was con verted to glucuronides during passing through the intestinal mucosa an d that luteolin 7-O-beta-glucoside was absorbed after hydrolysis to lu teolin, Free luteolin, its conjugates and methylated conjugates were p resent in rat plasma after dosing. This suggests that some luteolin ca n escape the intestinal conjugation and the hepatic sulfation/methylat ion. LC/MS analysis showed that the main conjugate which circulates in the blood was a monoglucuronide of the unchanged aglycone, Luteolin i n propyleneglycol was absorbed more rapidly than that in 0.5% carboxym ethyl cellulose. The plasma concentration of luteolin and its conjugat es reached the highest level 15 min and 30 min after dosing with luteo lin in propyleneglycol, respectively. HPLC analysis also allowed us to demonstrate the presence of free luteolin and its monoglucuronide in human serum after ingestion of luteolin. (C) 1998 Federation of Europe an Biochemical Societies.