甲鱼蛋α-葡萄糖苷酶抑制肽及其纳米运载体的体外胃肠消化特性

In Vitro Simulated Gastrointestinal Digestion Properties of Free and Nanocapsulatedα-Glucosidase Inhibitory Peptide from Soft-Shelled Turtle Egg

以甲鱼蛋α-葡萄糖苷酶抑制肽SGTLLHK为研究对象,评价胃肠消化对SGTLLHK抑制α-葡萄糖苷酶活性的影响;采用超高效液相色谱-串联四极杆飞行时间质谱分析SGTLLHK的消化特性及其产物;最后通过制备牛乳外泌体和固体脂质纳米颗粒(solid lipid nanoparticles,SLN)包埋SGTLLHK,测定颗粒特征(微观结构、Zeta电位、粒径、多分散性指数(polymer dispersity index,PDI)),并利用高效液相色谱考察包埋率及在胃肠道环境下的稳定性。结果表明:经胃消化后原肽SGTLLHK完全被降解,从消化产物中共鉴定到2条肽段(SGTLL、GTLL);进一步经肠消化后GTLL被完全降解,仅剩产物SGTLL。SGTLLHK的α-葡萄糖苷酶抑制活性在胃消化后显著上升,而在肠消化后显著下降,且低于原肽的抑制能力。SGTLLHK被成功包埋于外泌体、SLN中,其中外泌体包埋体系具有高度稳定性(粒径(125.87±2.66)nm,PDI 0.17±0.01),经胃肠消化后,SGTLLHK-外泌体颗粒体系保留率为72.52%,SGTLLHK-SLN保留率为48.43%,表明两者均能保护大部分原肽不被胃肠消化酶降解,且外泌体的保护作用优于SLN。

In this study,the effect of in vitro simulated gastrointestinal digestion on theα-glucosidase inhibitory activity of SGTLLHK,anα-glucosidase inhibitory peptide from soft-shelled turtle egg.The digestion properties and products of SGTLLHK were analyzed by ultra-high performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry(UHPLC-QTOF-MS/MS).Bovine milk exosomes and solid lipid nanoparticles(SLN)were then prepared to encapsulate SGTLLHK,and the particle characteristics(microstructure,zeta potential,particle size,polymer dispersity index(PDI))were investigated.The encapsulation efficiency and the stability of encapsulated SGTLLHK in a simulated gastrointestinal environment were determined by high performance liquid chromatography(HPLC).Results revealed that SGTLLHK was completely hydrolyzed after gastric digestion,and two peptides(SGTLL and GTLL)were identified from the digested products.After further intestinal digestion,GTLL was completely degraded,while SGTLL was still intact.Theα-glucosidase inhibitory activity of SGTLLHK was increased significantly after gastric digestion,and markedly decreased after intestinal digestion,reaching a level lower than that of the original peptide.SGTLLHK was successfully encapsulated in the exosomes and SLN.Meanwhile,the exosome encapsulation system showed high stability,having an average particle size of(125.87±2.66)nm and a PDI of 0.17±0.01.After gastrointestinal digestion,the retention rate of SGTLLHK-loaded exosomal particles was 72.52%,while that of SGTLLHK-SLN was 48.43%,indicating that both the exosomes and SLN could protect SGTLLHK against degradation by gastrointestinal digestive enzymes, the former being more effective than the latter.