牛乳酪蛋白体外模拟消化液的ACE抑制活性及其肠道吸收

本文对牛乳酪蛋白进行体外模拟消化,以ACE抑制活性为指征,LC-MS/MS确定水解物肽谱,并采用大鼠肠道模型对其吸收进行初步研究。结果为人工胃液消化、人工肠液消化、胃肠联合消化三种消化方式的水解度均随时间的延长而增大,单胃和单肠消化的ACE抑制率均随水解时间的延长先快速增加,随后逐渐降低,而胃肠联合的ACE抑制率则是先降低再增加,胃肠联合消化产生水解度最高为25.51%,其ACE抑制率在2 h时达到最高值为68.03%;LC-MS/MS测定消化液的肽谱,分析得出模拟消化后可能产生的ACE抑制肽有IPP、RYLGY、LHLPLP、AYFYPEL、RPKHPIKHQ及WQVLPNAVPAK;使用FITC标记酪蛋白进行体外模拟消化,SDS-PAGE和Tricine-SDS-PAGE都表明FITC-酪蛋白经过胃肠消化后荧光标记稳定存在,且水解物的分子量在5 ku以下;大鼠肠道吸收模型发现标记后的牛乳酪蛋白经模拟消化后在肠道吸收率大小依次为十二指肠吸收空肠吸收回肠吸收结肠吸收,主要在十二指肠吸收。

ACE Inhibitory Activity and Intestinal Absorption of Milk Casein Hydrolysates by in Vitro Simulated Digestion

Milk casein was digested by in vitro simulated gastro-intestinal fluid, and ACE inhibitory activity was used as an indicator in this study. Peptide spectrum of hydrolyzate was determined by LC-MS/MS, and its absorption was studied by intestinal model in rats. The results showed that the digestibility of artificial gastric juice digestion, artificial intestinal juice digestion and the combination of gastrointestinal juice increased with time, the ACE inhibition rates of monogastric and single intestinal digestion increased rapidly with the prolongation of hydrolysis time, followed by a gradual decrease, while the combination of gastric and intestinal digestion ACE inhibitory rate decreased first and then increased. The highest degree of hydrolysis of gastrointestinal combined digestion was 25.51%, and the ACE inhibition rate reached the highest value of 68.03% at 2 h; The peptide profiles of digestive juice were determined by LC-MS/MS. The results showed that ACE inhibitory peptides (including IPP, RYLGY, LHLPLP, AYFYPEL, RPKHPIKHQ and WQVLPNAVPAK) could be produced after simulated digestion. In vitro simulated digestion was performed using FITC labeled casein, SDS-PAGE and Tricine-PAGE showed that the fluorescent labeling FITC-casein was stable after the gastrointestinal digestion, and the molecular weight of the hydrolyzate was under 5kDa. The model of intestinal absorption in the rat showed that the intestinal absorptivity order of the labeled casein in the intestinal tract after digestion was as follows: duodenum absorption > jejunal absorption > ileal absorption > colon absorption, mainly absorbed in the duodenum.