The sialylation pattern of dietary glycopeptides is vital for inhibiting pathogens and modulating gut microbiota in elderly individuals

N-glycosylation is a post-translational modification of proteins that can influence the structure and function of glycoproteins. Edible birds nest (EBN) contains highly sialylated mucins with N-glycans and O-glycans, while casein glycomacropeptide (CGMP) is modified with only O-glycans. We prepare EBN sialoglycopeptides through sequential protease treatment and their inhibitory effects on pathogens, including Candida albicans, Helicobacter pylori, and avian influenza virus (AIV), as well as their modulation of gut microbiota in elderly individuals, were compared with CGMP. N-glycan analysis revealed the presence of multiantenna N-glycans, characterized by sialylation and bisecting GlcNAc in the EBN glycopeptides. EBN glycopeptides significantly inhibited C. albicans and H. pylori. However, the removal of terminal sialic acid from EBN glycopeptides resulted in a marked reduction of this inhibitory effect. Using Maackia Amurensis Lectin II as an AIV mimic, EBN glycopeptides effectively inhibited AIV adhesion to MDCK cells. In vitro fecal fermentation using fecal samples from elderly individuals revealed that the EBN glycopeptide group exhibited remarkable probiotic effects on the gut microbiota, increasing the relative abundance of beneficial bacteria such as Lactobacillus and Roseibacterium, while decreasing the relative abundance of harmful bacteria such as Escherichia-Shigella and Klebsiella. Overall, EBN glycopeptide, rich in sialylated N-glycans and O-glycans, strongly inhibited pathogenic microorganisms and showed superior probiotic properties compared to CGMP with sole O-glycosylation.