Gastric digestion of pea ferritin and modulation of its iron bioavailability by ascorbic and phytic acids in caco-2 cells
Gastric digestion of pea ferritin and modulation of its iron bioavailability by ascorbic and phytic acids in caco-2 cells
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DOI：
10.3748/wjg.v13.i14.2083
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发表时间：
2007-04-14
影响因子：
4.3
通讯作者：
Nair, K. Madhavan
中科院分区：
文献类型：
--
作者：
Bejjani, Satyanarayana;Pullakhandam, Raghu;Nair, K. Madhavan
目的：了解豌豆铁蛋白铁在caco-2细胞系模型中的消化稳定性及释放和肠道吸收机制。方法：采用盐分离-凝胶过滤层析法纯化豌豆籽铁蛋白。采用体外消化/Caco-2细胞模型，在存在或不存在抗坏血酸和植酸的情况下，评估铁蛋白铁的生物利用度。Caco-2细胞铁蛋白形成被用作铁摄取的替代标志物。采用电泳、凝胶过滤和圆二色光谱等方法对模拟胃pH条件下豌豆铁蛋白的结构变化进行了表征。结果：与空白消化液（3.7 +/- 1.8 ng/mg蛋白）相比，FeSO4 （19.3 +/- 9.8 ng/mg蛋白）和豌豆铁蛋白（13.9 +/- 6.19 ng/mg蛋白）显著增加caco-2细胞铁蛋白形成（P < 0.001）。抗坏血酸提高了豌豆铁蛋白铁的生物利用度，植酸降低了豌豆铁蛋白铁的生物利用度。然而，无论是否存在抗坏血酸，含有豌豆铁蛋白的caco-2细胞的铁蛋白含量都明显低于含有FeSO4的细胞。在胃pH值上，无论是在天然PAGE还是SDS-PAGE上，都没有观察到胃蛋白酶存在时与铁蛋白对应的条带。凝胶过滤色谱和圆二色光谱显示了pH依赖性的四级和二级结构损失。结论：在胃条件下，酸诱导的蛋白结构改变和解离使豌豆铁蛋白的铁核释放到消化介质中。释放的铁与饮食因素相互作用，导致豌豆铁蛋白铁的生物利用度调节，类似于非血红素铁的典型特征。(c) 2007年WJG出版社。版权所有。
AIM: To understand the digestive stability and mechanism of release and intestinal uptake of pea ferritin iron in caco-2 cell line model.METHODS: Pea seed ferritin was purified using salt fractionation followed by gel filtration chromatography. The bioavailability of ferritin iron was assessed using coupled in vitro digestion/Caco-2 cell model in the presence or absence of ascorbic acid and phytic acid. Caco-2 cell ferritin formation was used as a surrogate marker of iron uptake. Structural changes of pea ferritin under simulated gastric pH were characterized using electrophoresis, gel filtration and circular dichroism spectroscopy.RESULTS: The caco-2 cell ferritin formation was significantly increased (P < 0.001) with FeSO4 (19.3 +/- 9.8 ng/mg protein) and pea ferritin (13.9 +/- 6.19 ng/mg protein) compared to the blank digest (3.7 +/- 1.8 ng/ mg protein). Ascorbic acid enhanced while phytic acid decreased the pea ferritin iron bioavailability. However, either in the presence or absence of ascorbic acid, the ferritin content of caco-2 cells was significantly less with pea ferritin than with FeSO4. At gastric pH, no band corresponding to ferritin was observed in the presence of pepsin either on native PAGE or SDS-PAGE. Gel filtration chromatography and circular dichroism spectroscopy revealed a pH dependent loss of quaternary and secondary structure.CONCLUSION: Under gastric conditions, the iron core of pea ferritin is released into the digestive medium due to acid induced structural alterations and dissociation of protein. The released iron interacts with dietary factors leading to modulation of pea ferritin iron bioavailability, resembling the typical characteristics of non-heme iron. (c) 2007 The WJG Press. All rights reserved.