Bioavailability Assessment of Isoflavones between Soybean and Soybean Sprout in Rat

Kim, Eun Mi; Kim, Kyung Jin; Choi, Jin Ho; Chee, Kew Mahn

Abstract

Rodent models have been used to study the anticarcinogenic properties of the soy isoflavones, particularly genistein, but there is little information regarding the pharmacokinetics of the absorption and excretion of genistein. In this study, rats were given a single oral dose of genistein (20 mg/kg body wt) or an equivalent dose as Myougjoonamul-kong and Myoungjoonamul soy sprouts. Concentrations of genistein were measured in plasma, urine and feces at intervals up to 48 hr after dosing. Maximum peak of plasma genistein concentration is 8 hr after dosing, and its concentration is 13.2, 7.4 mol/L in soy and soy sprout-treated rats, respectively. In pure genistein treated rats, maximum peak of plasma genistein concentration is 2 hr after dosing (5.7 mol/L). The percentage of dose recovered in urine over 48 hr was not different between groups (21.2% soy treated : 18.2% soy sprout treated : 16.1% pure genistein treated). There were no significant differences between groups in the recovery of genistein in feces (19.5%, 7.5% and 15.7% of doses, respectively). 6.9% and 6.07% of the daidzein from the soy and soy sprout treated was recovered in the feces.