King R A, Broadbent J L, Head R J
CSIRO Division of Human Nutrition, Adelaide, South Australia.
J Nutr. 1996 Jan;126(1):176-82. doi: 10.1093/jn/126.1.176.
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 weight) or an equivalent dose of its glycone forms, as an isoflavone-rich soy extract. Concentrations of genistein were measured in plasma, urine and feces at intervals up to 48 h after dosing. Plasma genistein concentration at 2 h after dosing was 11.0 +/- 2.3 mumol/L in genistein-treated rats compared with 4.93 +/- 0.22 mumol/L (P = 0.025) in soy extract-treated rats, but there were no significant differences at 8 h and later times. The mean urinary excretion rate during the first 2 h after dosing was more than 10 times higher in the genistein group compared with the soy extract group (0.27 +/- 0.08 mumol/h and 0.020 +/- 0.011 mumol/h, respectively, P = 0.017) but the percentage of dose recovered in urine over 48 h was not different between groups (19.9 +/- 2.4% genistein treated; 17.5 +/- 1.1% soy extract treated). There were no significant differences between groups in the recovery of genistein in feces (21.9 +/- 2.8% and 21.1 +/- 2.5% of dose, respectively). Only 6.1 +/- 0.9% of the daidzein from the soy extract was recovered in the feces. The results suggest that the extent of absorption of genistein is similar for the glycone and aglycone forms. Although higher initial plasma concentrations may be achieved with the aglycone, similar long-term concentrations exist for both forms of isoflavone.
啮齿动物模型已被用于研究大豆异黄酮，尤其是染料木黄酮的抗癌特性，但关于染料木黄酮吸收和排泄的药代动力学信息很少。在本研究中，给大鼠单次口服一剂染料木黄酮（20毫克/千克体重）或等量剂量的其糖苷形式，作为富含异黄酮的大豆提取物。在给药后长达48小时的间隔时间内，测定血浆、尿液和粪便中染料木黄酮的浓度。与大豆提取物处理的大鼠相比，染料木黄酮处理的大鼠给药后2小时血浆染料木黄酮浓度为11.0±2.3微摩尔/升，而大豆提取物处理的大鼠为4.93±0.22微摩尔/升（P = 0.025），但在8小时及以后的时间没有显著差异。给药后前2小时，染料木黄酮组的平均尿排泄率比大豆提取物组高10倍以上（分别为0.27±0.08微摩尔/小时和0.020±0.011微摩尔/小时，P = 0.017），但48小时内尿液中回收的剂量百分比在两组之间没有差异（染料木黄酮处理组为19.9±2.4%；大豆提取物处理组为17.5±1.1%）。两组之间粪便中染料木黄酮的回收率没有显著差异（分别为剂量的21.9±2.8%和21.1±2.5%）。大豆提取物中的大豆苷元只有6.1±0.9%在粪便中回收。结果表明，染料木黄酮的糖苷和苷元形式的吸收程度相似。虽然苷元形式可能会达到更高的初始血浆浓度，但两种形式的异黄酮长期浓度相似。
