体外模拟胃肠道对鲫鱼卵唾液酸糖蛋白的降解作用

Degradation of Sialoglycoprotein from Carassius auratus Eggs by Simulated Gastrointestinal Tract in Vitro

鲫鱼卵唾液酸糖蛋白(sialoglycoprotein from Carassius auratus eggs,Ca-SGP)是从鲫鱼卵中筛选分离出的一种新型唾液酸糖蛋白,具有改善骨代谢、调节免疫力等功效。然而Ca-SGP属于大分子质量(195.35 kDa)物质,其如何通过胃肠道被降解并利用的仍不清楚。本实验旨在研究胃肠液及大肠肠道菌群对Ca-SGP的降解作用,以期为深入探索Ca-SGP作用机理提供参考。本实验以唾液酸糖蛋白为研究对象,采用体外静态胃肠模拟系统,通过检测不同阶段的产物分子质量、pH值、唾液酸含量及还原糖质量浓度来研究胃肠液及大肠肠道菌群对Ca-SGP的降解作用。结果表明:经过胃肠道消化后Ca-SGP的分子质量减小,唾液酸含量减少,还原糖质量浓度增加,说明胃肠液对Ca-SGP有一定的降解作用,Ca-SGP糖链末端的活性因子唾液酸能够在胃肠消化酶的作用下发生脱落;Ca-SGP经过肠道菌群发酵后,分子质量不断减小,还原糖质量浓度降低,说明Ca-SGP能够不断被微生物发酵并且利用,发酵后溶液pH值呈现逐渐下降趋势,推测可能与产生短链脂肪酸等酸性物质有关。提示胃肠液对Ca-SGP有一定的降解作用,大肠肠道菌群能够进一步降解Ca-SGP并且利用其降解产物。

Sialoglycoprotein from Carassius auratus eggs(Ca-SGP)is a novel sialic acid glycoprotein which has the functions of improving bone metabolism and regulating immunity.However,as a large molecular mass substance(195.35 kDa),how Ca-SGP is digested and absorbed by the gastrointestinal tract is yet not clear.This paper aims to study the degradation of Ca-SGP by simulated gastrointestinal fluids and colonic intestinal flora,which is expected to provide theoretical support for further exploration of the mechanism of action of Ca-SGP in vivo.The degradation of Ca-SGP by simulated gastrointestinal fluid and intestinal flora in vitro was evaluated by detecting the molecular mass,pH,sialic acid content and reducing sugar content at different stages of digestion.The results showed that the molecular mass of Ca-SGP decreased,the content of sialic acid declined and the content of reducing sugar increased after gastrointestinal digestion,which indicated that the simulated gastrointestinal fluids can degrade Ca-SGP,and the gastrointestinal digestive enzymes can cause the active factor sialic acid to fall off the end of the Ca-SGP sugar chain.The molecular mass of Ca-SGP and the reducing sugar content were reduced after fermentation by the intestinal bacteria,indicating that Ca-SGP can be continuously fermented and utilized by microorganisms,and the pH gradually decreased as fermentation proceeded,which may be related to the production of acidic substances such as short-chain fatty acids.Hence,the simulated gastrointestinal fluids can degrade Ca-SGP,and the intestinal microflora can further degrade it and utilize its degradation products.