Neu5Acα2-8Neu5Acα2-3Galβ1-4GlcNAc

Neu5Acα2-8Neu5Acα2-3Galβ1-4GlcNAc  (disialyl lacto-N-triose II or DSLNT II) is a sialylated tetrasaccharide human milk oligosaccharide (HMO) characterized by a unique α2-8 linked disialyl motif where N-acetylneuraminic acid (Neu5Ac) caps another Neu5Acα2-3Gal, extended to the type-2 chain GlcNAc core. This structure, biosynthesized by ST8Sia-II (GD3 synthase) followed by ST3Gal-III/IV on lacto-N-triose II, represents a minor but bioactive HMO fraction (<1% total HMOs) pivotal for neonatal immunity and gut maturation. The terminal α2-8/α2-3 sialyl configuration mimics ganglioside epitopes, serving as high-affinity decoy receptors for sialic acid-binding respiratory/enteric viruses (e.g., influenza, norovirus) and selectins mediating leukocyte trafficking. In prebiotic contexts, it selectively nourishes Bifidobacterium longum subsp. infantis sialidases, modulating microbiota sialometabolism and reducing pathogen adhesion. Therapeutically, synthetic DSLNT II probes Siglec-7/9 inhibitory receptors for cancer immunotherapy, anti-inflammatory glycotherapeutics, and infant formula supplementation to mimic colostrum sialylation patterns protective against necrotizing enterocolitis (NEC). Appearance White to pale yellow lyophilized amorphous powder. Highly hygroscopic; supplied freeze-dried under nitrogen. Source Trace levels in transitional human milk/colostrum (0.01-0.1 g/L). Enzymatic/chemical synthesis using porcine/bacterial ST8Sia2 on Neu5Acα2-3Galβ1-4GlcNAc acceptor. Molecular Weight and Structure Formula: C41H70N4O35; MW 1,271.01 g/mol (reducing tetrasaccharide). Neu5Acα2→8Neu5Acα2→3Galβ1→4GlcNAc (branched disialyl type-2 motif). Sugar Specificity α2-8/α2-3 disialyl selectivity for viral hemagglutinins, Siglec-7. Resistant to human sialidases; cleaved by bacterial NanI/NanH. Biological Activity Potent viral decoy: Inhibits influenza A/B attachment (IC50 0.1-1 mM). Bifidogenic: Enhances B. infantis growth 3-fold via dsSia utilization. Purity and Microbial Contamination ≥95% by HPAEC-PAD/NMR for analytical standards. Endotoxin <0.01 EU/mg; sterile bioburden <1 CFU/mg. Identity and Quality Control 2D-NMR (NOESY/HSQC confirming α2-8 linkage), HRMS (m/z 1270 [M-H]-). Linkage analysis (keratanase digestion), sialic acid quantification. Shelf Life and Storage 2 years at -80°C lyophilized; solutions stable 1 week at -20°C. Anhydrous, light/moisture protected; single-use aliquots. Applications Antiviral HMO therapeutics; glycan arrays for sialyl lectin screening. Prebiotic fortification, NEC prevention studies. Key Characteristics Extreme water solubility (>500 mg/mL); virus-specific dsSia motif. Non-cytotoxic, stable poly-sialic acid mimic. Citation Links https://pmc.ncbi.nlm.nih.gov/articles/PMC9235823/ https://pmc.ncbi.nlm.nih.gov/articles/PMC11847054/ https://pmc.ncbi.nlm.nih.gov/articles/PMC9304252/ https://www.sciencedirect.com/science/article/pii/S2161831322010110 https://www.nature.com/articles/s41598-018-23025-x https://pubchem.ncbi.nlm.nih.gov/compound/91862595 https://glyconnect.expasy.org/hmo/structures https://pmc.ncbi.nlm.nih.gov/articles/PMC6753469/ https://www.jstage.jst.go.jp/article/tigg/30/172/30_1734.1SE/_article https://researchonline.ljmu.ac.uk/id/eprint/6683/4/Functional%20properties,%20structural%20studies%20and%20chemoenzymatic%20synt