Total synthesis of zwitterionic PS A2 oligosaccharides from <i>Bacteroides fragilis</i>.

Li, Xinxin; Pan-Gao, Qingzhi; Wan, Yongyong; Zeng, Fuxing; Qi, Jianying; Tu, Yuanhong; Wang, Liming; Wang, Zhen et al. · Sci Adv · 2025

basic_science · Level V

Where this comes from

Abstract

Zwitterionic polysaccharides have unique structures and can elicit T cell-dependent immune responses. To unravel their molecular mode of action and develop potential alternatives for carrier proteins in carbohydrate-based vaccines, we here describe a total synthesis of zwitterionic PS A2 oligosaccharides from <i>Bacteroides fragilis</i>. The pentasaccharide and decasaccharide bearing one or two repeating units were efficiently synthesized via convergent glycosylation strategy. The ingenious protecting groups have enabled the stereoselectivity of glycosylation. A unique synthetic approach was developed to introduce the chiral 3-hydroxybutanoic acid side chain on mannoheptose, which proved very challenging to form in this skeleton.

Medical subject headings