Improved Glycoqueuing Strategy Reveals Novel?2,3-Linked Di-/Tri-Sialylated Oligosaccharide Isomers in Human Milk br

Sialylated human milk oligosaccharides (SHMOs) possess unique biological activities. Qualitative and quantitative analyses of SHMOs at different lactation stages are limited by interference from neutral oligosaccharides, glycan structural complexity, and low detection sensitivity. Herein, our previously developed glycoqueuing strategy was improved and applied to enable an isomer-specific quantitative comparison of SHMOs between colostrum milk (CM) and mature milk (MM). A total of 49 putative structures were determined, including 1 alpha 2,6-linked and 13 alpha 2,3-linked isomers separated from seven newly discovered SHMO compositions. The content of most oligosaccharides was more than 50% lower in MM than in CM, and alpha 2,3-sialylation was observed in 43.74% of SHMOs from CM and 22.95% of SHMOs from MM. Finally, the fucosylation level of the SHMOs increased from 16.45 to 22.28% with prolonged lactation. These findings provide the basis for further studies on the structure-activity relationship of SHMOs and a blueprint to improve infant formula.

Automated summary

This study improved and applied a glycoqueuing strategy to quantitatively compare the sialylated human milk oligosaccharides (SHMOs) between colostrum milk (CM) and mature milk (MM). The results showed that most oligosaccharides had more than 50% lower content in MM compared to CM, and a higher proportion of alpha 2,3-sialylation was observed in SHMOs from CM. Additionally, the fucosylation level of SHMOs increased with prolonged lactation.