Crespy, Vanessa, Christine Morand, Catherine Besson, Nicole Cotelle, Hervé Vé zin, Christian Demigné , and Christian Ré mé sy. The splanchnic metabolism of flavonoids highly differed according to the nature of the compound. Am J Physiol Gastrointest Liver Physiol 284: G980-G988, 2003; 10.1152/ajpgi.00223.2002.-The absorption and splanchnic metabolism of different flavonoids (namely quercetin, kaempferol, luteolin, eriodictyol, genistein, and catechin) were investigated in rats after an in situ perfusion of jejunum plus ileum (14 nmol/min). Net transfer across the brush border ranged widely according to the perfused compound (from 78% for kaempferol to 35% for catechin). This variation seems linked to the lipophilicity of a given flavonoid rather than to its three-dimensional structure. Except for catechin, conjugated forms of perfused flavonoids were also detected in the intestinal lumen, but the extent of this secretion depended on the nature of the perfused compounds (52% for quercetin to 11% for genistein). For some of the perfused aglycones, biliary secretion was an important excretion route: 30% of the perfused dose for genistein but only 1% for catechin. Thus the splanchnic metabolism of flavonoid is controlled by several factors: 1) the efficiency of their transfer through the brush border, 2) the intensity of the intestinal secretion of conjugates toward the mucosal and serosal sides, respectively, and 3) the biliary secretion of conjugates. These data suggested that the splanchnic metabolism of perfused flavonoids depends on the nature of the compound considered, which in turn influences their availability for peripheral tissues. absorption; biliary excretion; rats FLAVONOIDS are phenolic secondary plant metabolites responsible for much of the color and flavor of plant foods. They are ubiquitous in fruits, vegetables, and beverages, with more than 4,000 chemically different flavonoids identified to date. They are assigned to different groups according on their structure: anthocyanins, flavonols, flavones, catechins, isoflavones, and flavonones (1,8,38,43). Owing to their ubiquity in plants, humans are constantly exposed to a wide variety of flavonoids. A wealth of beneficial properties has been reported: antibacterial, antioxidant, anti-inflammatory, and anticarcinogenic effects (2, 21, 29) and estrogenic effects for isoflavones (33). Understanding the absorption and metabolism of dietary flavonoids is fundamental to determining their potential biological activity.The small intestine is a crucial site for the absorption of dietary flavonoids. In this tissue, aglycones are metabolized by intestinal conjugation enzymes, and the resulting metabolites are then secreted toward the mucosal and/or serosal sides (5, 6, 10, 13, 37). Circulating forms of absorbed flavonoids have been identified as methylated and/or glucuronidated and/or sulfated metabolites (9,12,19,23,39), resulting from the conjugative activities of both liver and intestine (7). Flavonoid metabolites are then eliminated in urine and by the bili...
