Neu5Acα2,3Galβ1,4GlcNAc

Neu5Acα2,3Galβ1,4GlcNAc (sialyl lacto-N-triose II or Neu5Acα2-3LacNAc) is a fundamental sialylated trisaccharide and key building block of human milk oligosaccharides (HMOs), featuring N-acetylneuraminic acid (Neu5Ac) in an α2-3 linkage to the galactose of a type-2 N-acetyllactosamine (LacNAc, Galβ1-4GlcNAc) unit. This motif, synthesized by ST3Gal3/4 sialyltransferases, constitutes the core of major HMOs like LSTa (sialyllacto-N-tetraose a) and disialyl variants, comprising 5-15% of total milk sialylation. The α2-3 sialyl configuration provides a high-affinity epitope for enteric pathogens (e.g., Vibrio cholerae, E. coli K99), rotavirus, and selectins (E/L-selectin) involved in leukocyte rolling during inflammation. As a prebiotic, it selectively fuels Bifidobacterium bifidum/infantis sialidases, limiting pathogen adhesion while promoting barrier integrity and immune maturation in neonates. Therapeutically, it serves in glycan microarrays for lectin/Siglec profiling, antiviral decoy design, infant formula supplementation against NEC/sepsis, and cancer glycoengineering targeting sialyl-Tn/Lewis antigens, with emerging roles in modulating gut-brain axis via sialometabolism.

Appearance

• White to off-white lyophilized amorphous or crystalline powder.
• Highly hygroscopic; typically freeze-dried for stability.​

Source

• Prevalent in human milk (0.5-2 g/L), colostrum, and mucins.
• Chemoenzymatic production via ST3Gal on Galβ1-4GlcNAc acceptor.​

Molecular Weight and Structure

• Formula: C23H38N2O19; MW 634.55 g/mol (reducing form).
• Neu5Acα2→3Galβ1→4GlcNAc (axial α2,3-sialyl type-2 chain).​

Sugar Specificity

• α2,3-sialyl selective for bacterial sialidases, E-selectin, Siglec-3/5.
• Distinguished from α2,6 isomer by sialic acid orientation.​

Biological Activity

• Pathogen decoy: Blocks rotavirus/ETEC adhesion (IC50 1-5 mM).
• Bifidogenic: Stimulates B. breve growth, anti-inflammatory via TLR4 modulation.​

Purity and Microbial Contamination

• ≥98% purity by anion-exchange HPLC/NMR.
• Endotoxin <0.05 EU/mg; sterile filtration <5 CFU/g bioburden.​

Identity and Quality Control

• 1H-NMR (H3eq axial shift ~2.7 ppm), HRMS (m/z 633 [M-H]-).
• Exo-α2,3-sialidase digestion, monosaccharide analysis (DMB-HPLC).​

Shelf Life and Storage

• 3 years at -20°C lyophilized; aqueous stable 2 weeks at 4°C.
• Desiccated, light-protected; avoid >3 freeze-thaw cycles.​

Applications

• HMO standards for LC-MS/MS profiling; antiviral glycotherapeutics.
• Prebiotic fortification, glycan arrays, infant nutrition research.

Key Characteristics

• Excellent water solubility (>100 mg/mL); stable sialyl-LacNAc epitope.
• Non-toxic, bifidoselective, anti-adhesive properties.​

Citation Links

• https://pubchem.ncbi.nlm.nih.gov/compound/44630015​
• https://pubchem.ncbi.nlm.nih.gov/compound/91862595​
• https://pmc.ncbi.nlm.nih.gov/articles/PMC9235823/​
• https://www.sciencedirect.com/science/article/pii/S2161831322010110​
• https://pmc.ncbi.nlm.nih.gov/articles/PMC9304252/​
• https://pubs.rsc.org/en/content/articlehtml/2022/sd/d1sd00023c​
• https://www.jstage.jst.go.jp/article/tigg/30/172/30_1734.1SE/_article​
• https://pmc.ncbi.nlm.nih.gov/articles/PMC9709932/​
• https://glyconnect.expasy.org/hmo/structures​
• https://pubchem.ncbi.nlm.nih.gov/compound/53384365