Andlauer W, Kolb J, Fürst P
Institute for Biological Chemistry and Nutrition, University of Hohenheim, D-70593 Stuttgart, Germany.
J Nutr. 2000 Dec;130(12):3021-7. doi: 10.1093/jn/130.12.3021.
Studies suggest a variety of biological effects of soybean isoflavones, but there is little information regarding small intestinal absorption and metabolism. The aim of this study was to investigate intestinal handling of luminally administered soybean-based tofu in an isolated preparation of the luminally and vascularly perfused rat small intestine (male Sprague-Dawley, approximately 45 d old). A synthetic emulsion free from blood components was used as vascular medium, with a perfluorocarbon as oxygen carrier. Luminal media consisted of tofu, predigested with pepsin and pancreatin and emulsified with bile acids, containing 39. 5 micromol/L genistein compounds and 19.1 micromol/L daidzein compounds. Viability of the organ preparation was maintained during the entire perfusion, confirmed by lack of significant differences between tofu and control perfusion experiments for arterial pressure, glucose consumption, oxygen uptake, lactate-pyruvate ratio and acid-base homeostasis. Daidzein (8.9%) and genistein (8.0%) compounds from tofu exhibited almost the same (P: > 0.05) absorption rate during small intestinal passage. The majority of the absorbed genistin appeared vascularly as genistein (4.4%), in addition to minor amounts of unchanged genistin (2.1%) and genistein glucuronide (1.5%). In the luminal effluent, a considerable increase of genistein (338%) as well as daidzein (190%) as cleavage products of the glucosides and malonyl-glucosides was observed. The distribution of daidzein compounds in the small intestine was not different from that of genistein compounds (P: > 0.05), except for the blood vessels, which had extremely low total amounts. Sulfate derivatives of genistein and daidzein compounds were not detectable. An effect of tofu ingredients was observed on absorption rate of genistin, on glucuronidation and on distribution of genistein glucuronide in the intestine.
研究表明大豆异黄酮具有多种生物学效应，但关于其在小肠的吸收和代谢的信息却很少。本研究的目的是在离体的腔面和血管灌注大鼠小肠（雄性斯普拉格-道利大鼠，约45日龄）中，研究经腔面给予大豆基豆腐后的肠道处理情况。一种不含血液成分的合成乳剂用作血管灌注介质，全氟碳作为氧载体。腔面介质由经胃蛋白酶和胰酶预消化并用胆汁酸乳化的豆腐组成，含有39.5微摩尔/升的染料木黄酮化合物和19.1微摩尔/升的大豆苷元化合物。在整个灌注过程中，器官制备的活力得以维持，豆腐灌注实验与对照灌注实验在动脉压、葡萄糖消耗、氧摄取、乳酸-丙酮酸比值和酸碱平衡方面无显著差异，证实了这一点。豆腐中的大豆苷元（8.9%）和染料木黄酮（8.0%）化合物在小肠通过过程中表现出几乎相同（P＞0.05）的吸收率。吸收的染料木苷大部分以染料木黄酮的形式出现在血管中（4.4%），此外还有少量未变化的染料木苷（2.1%）和染料木黄酮葡萄糖醛酸苷（1.5%）。在腔面流出物中，观察到作为糖苷和丙二酰糖苷裂解产物的染料木黄酮（338%）以及大豆苷元（190%）显著增加。大豆苷元化合物在小肠中的分布与染料木黄酮化合物无异（P＞0.05），但血管中的总量极低。未检测到染料木黄酮和大豆苷元化合物的硫酸盐衍生物。观察到豆腐成分对染料木苷的吸收率、葡萄糖醛酸化以及染料木黄酮葡萄糖醛酸苷在肠道中的分布有影响。
