Evidence for lack of absorption of soy isoflavone glycosides in humans, supporting the crucial role of intestinal metabolism for bioavailability
Evidence for lack of absorption of soy isoflavone glycosides in humans, supporting the crucial role of intestinal metabolism for bioavailability
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DOI：
10.1093/ajcn/76.2.447
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发表时间：
2002-08-01
影响因子：
7.1
通讯作者：
Heubi, JE
中科院分区：
文献类型：
--
作者：
Setchell, KDR;Brown, NM;Heubi, JE
背景：大豆黄酮和染料木黄酮天然存在于大多数大豆食品中，几乎只与糖结合。关于甘草苷的生物利用度存在争议，并且甘草酮在人体内的肠道吸收机制尚不清楚。来自肠灌注和体外细胞培养研究的证据表明，甘草苷吸收不良，但甘草酮是生物可利用的，并出现在血浆中的高浓度，无论他们是否被摄入的苷元或糖苷共轭物。目的：目的是确定是否从肠道吸收完整的甘草苷和到达外周循环不变。设计：在健康成年人摄入50 mg β-糖苷（大豆苷或染料木苷）或250 mL主要含有β-糖苷的豆奶之前和之后，以一定的时间间隔收集血浆。固相萃取后，采用电喷雾质谱法检测血浆中的大豆苷和染料木苷。通过气相色谱-质谱分析确认了大豆黄酮的生物利用度。结果：具体和敏感的电喷雾质谱法未能检测到甚至痕量的大豆苷或染料木苷在血浆中收集的1，2，和8小时后，他们摄入的纯化合物或在soyfood矩阵。然而，血浆中富含的β-葡萄糖醛酸酶和硫酸酯酶制剂与组合水解的异黄酮苷类化合物。结论：异黄酮苷类化合物不完整吸收整个健康成人的肠上皮细胞，其生物利用度需要初始水解的糖部分肠β-葡萄糖苷酶摄取到外周循环。
Background: The isoflavones daidzein and genistein occur naturally in most soyfoods, conjugated almost exclusively to sugars. Controversy exists regarding the extent of bioavailability of isoflavone glycosides, and the mechanism of intestinal absorption of isoflavones in humans is unclear. Evidence from intestinal perfusion and in vitro cell culture studies indicates that isoflavone glycosides are poorly absorbed, yet isoflavones are bioavailable and appear in high concentrations in plasma, irrespective of whether they are ingested as aglycones or glycoside conjugates.Objective: The objective was to determine whether isoflavone glycosides are absorbed from the intestine intact and reach the peripheral circulation unchanged.Design: Plasma was collected at timed intervals before and after healthy adults ingested 50 mg of one of the isoflavone beta-glycosides (daidzin or genistin) or 250 mL soymilk containing mainly isoflavone glycosides. Electrospray ionization mass spectrometry was used to detect daidzin and genistin after solid-phase extraction of these conjugates from plasma. Bioavailability of isoflavones was confirmed by gas chromatography-mass spectrometry analysis.Results: Specific and sensitive electrospray mass spectrometry failed to detect even traces of daidzin or genistin in plasma collected 1, 2, and 8 h after their ingestion as pure compounds or in a soyfood matrix. However, plasma was enriched in isoflavones that were hydrolyzable with a combined beta-glucuronidase and sulfatase enzyme preparation.Conclusion: Isoflavone glycosides are not absorbed intact across the enterocyte of healthy adults, and their bioavailability requires initial hydrolysis of the sugar moiety by intestinal beta-glucosidases for uptake to the peripheral circulation.