Daidzein and genistein but not their glucosides are absorbed from the rat stomach

Absorption of isoflavone aglycones and glucosides was compared in rats. Dai dzein, genistein, daidzin and genistin were orally administered at a dose o f 7.9 mu mol/kg in 25 mM Na2CO3 and next their metabolite concentration in blood plasma was monitored for 30 min, After isoflavone glucosides administ ration, their metabolites appeared in plasma with a few minutes delay as co mpared to aglycones, which suggested that aglycones, but not glucosides, we re absorbed already in the rat stomach, This observation,vas confirmed when absorption site was restricted solely to the stomach and absorption was sh own to be independent of the vehicle pH used for administration. (C) 1999 F ederation of European Biochemical Societies.