Division BIOANALYTIK Weihenstephan, Research Center for Nutrition and Food Sciences (Z. I. E. L.), Technical University of Munich, Alte Akademie 10, D-85350 Freising, Germany.
Chair of Analytical Food Chemistry, Technical University of Munich, Alte Akademie 10, D-85350 Freising, Germany.
Nutrients. 2017 Sep 1;9(9):969. doi: 10.3390/nu9090969.
Generating bioavailability data from in vivo studies is time-consuming and expensive. In vitro simulation can help to investigate factors influencing bioavailability or facilitate quantifying the impact of such factors. For folates, an efficient deconjugation of polyglutamates to the corresponding monoglutamates is crucial for bioavailability and highly dependent on the food matrix. Therefore, the bioaccessibility of folates of different foodstuffs was examined using a simulated digestion model with respect to folate stability and the efficiency of deconjugation. For realistic simulated deconjugation, porcine brush border membrane was used during the phase of the simulated digestion in the small intestine. For a better understanding of folate behaviour during digestion, single folate monoglutamates were also investigated with this in vitro digestion model. The results for bioaccessibility were compared with data from a human bioavailability study. They support the idea that both stability and deconjugation have an influence on bioaccessibility and thus on bioavailability. Tetrahydrofolate is probably lost completely or at least to a high extent and the stability of 5-methyltetrahydrofolate depends on the food matrix. Additionally, 5-methyltetrahydrofolate can be oxidised to a pyrazino-s-triazine (MeFox), whose absorption in the human intestinal tract was shown tentatively.
从体内研究中生成生物利用度数据既耗时又昂贵。体外模拟有助于研究影响生物利用度的因素或便于量化这些因素的影响。对于叶酸而言，将多谷氨酸有效地去共轭化为相应的单谷氨酸对于生物利用度至关重要，并且高度依赖于食物基质。因此，使用模拟消化模型研究了不同食物中的叶酸的生物可及性，以考察叶酸稳定性和去共轭化效率。为了实现现实的模拟去共轭化，在模拟消化的小肠阶段使用了猪肠刷状缘膜。为了更好地了解消化过程中叶酸的行为，还使用该体外消化模型研究了单叶酸单谷氨酸盐。将生物利用度的结果与来自人体生物利用度研究的数据进行了比较。结果表明，稳定性和去共轭化均会影响生物可及性，进而影响生物利用度。四氢叶酸可能会完全丢失，或者至少会大量丢失，而 5-甲基四氢叶酸的稳定性取决于食物基质。此外，5-甲基四氢叶酸可以被氧化为吡嗪并三嗪（MeFox），其在人体肠道中的吸收情况被初步证明。
