Establishment of safely and effectively consumption methods of soy isoflavone

过量摄入异黄酮可能导致内分泌紊乱，因此需要确定最大摄入量。大豆异黄酮含有异黄酮苷元，如染料木素、大豆黄酮和糖苷，以及它们的糖苷，它们被认为具有相同的肠通透性。在本研究中，我们旨在详细评价这些异黄酮的吸收机制，并通过比较吸收特性来检验。我们使用Caco-2细胞和人工膜渗透实验（PAMPA）在不同的pH梯度和等pH条件下进行了体外研究。在质子梯度存在时，某些异黄酮苷元的渗透系数比没有质子梯度时大。此外，在Caco-2细胞中观察到被动和主动转运。PAMPA对异黄酮苷元的被动转运评价表明，异黄酮苷元的被动转运是有效的。这些苷元被认为在人体肠道中具有高通透性。因此，在食用这些化合物时要小心。此外，我们还以同样的方法评估了其他类黄酮苷元的吸收。对比Caco-2细胞和PAMPA对黄酮的渗透特性，结合其物理化学性质，表明根据pH-partition假说，黄酮可以通过被动扩散进行有效的转运。

Excessive ingestion of isoflavones may result in endocrine disruption, hence a maximum intake level needs to be established. Soy isoflavones contain isoflavone aglycones, such as genistein, daidzein, and glycitein, and their glygosides, which are considered to have the same intestinal permeability. In this study, we aimed to evaluate in detail the absorption mechanisms of these isoflavones, and examine by comparing the characteristics of absorption. We performed in vitro studies using Caco-2 cells and an artificial membrane permeation assay(PAMPA) with different pH gradients and iso-pH conditions. The permeability coefficients of some isoflavone aglycones were greater in the presence of a proton gradient than its absence. Furthermore, passive and active transports were observed in Caco-2 cells. Evaluation of passive transport by PAMPA suggested that isoflavone aglycones were transported efficiently by passive diffusion. These aglycones have been suggested to have high permeability in the human intestine. Therefore, care should be taken when consuming these compounds. Furthermore, we evaluated the absorption of other flavonoid aglycones in the same manner. A comparison of the permeability characteristics among flavanones using Caco-2 cells and PAMPA as well as consideration of their physicochemical properties, suggested that the flavanones were transported efficiently via passive diffusion according to the pH-partition hypothesis.