Lacto-N-Biose

Lacto-N-Biose (LNB) is a disaccharide and a fundamental building block of human milk oligosaccharides (HMOs), particularly classified as a type I chain oligosaccharide. It is composed of galactose (Gal) and N-acetylglucosamine (GlcNAc) linked by a β-(1→3) glycosidic bond.

• Abbreviation: LNB
• IUPAC Name (extended): 2-Acetamido-2-deoxy-3-O-(β-D-galactopyranosyl)-D-glucopyranose
• IUPAC Name (condensed): GlcNAc-(β1-3)-Gal-(β1-4)-Glc
• Molecular Formula: C14H25NO11
• Molecular Mass: 383.35 g/mol
• CAS Number: 50787-09-2

Chemical and Structural Description

• Structure: Lacto-N-biose consists of a disaccharide formed by a galactose unit linked β1-3 to N-acetylglucosamine (GlcNAc). It is a reducing sugar with biological activity as an acceptor substrate for enzymes like α1,2-fucosyltransferase.
• Physical Properties: It typically appears as a white to off-white powder, soluble in water, requiring specific storage conditions (-20°C to -80°C) to maintain stability.
• Source and Production: LNB is naturally found in human breast milk as part of more complex HMOs. It can be synthesized chemically or produced via microbial fermentation involving enzymatic biosynthesis pathways.

Biological and Functional Context

• Role in HMOs: Lacto-N-biose is the core disaccharide unit of type I HMOs, which are predominant in human milk and contribute to establishing a healthy infant gut microbiome.
• Prebiotic Activity: It selectively promotes the growth of beneficial Bifidobacterium species such as Bifidobacterium bifidum, Bifidobacterium longum subsp. infantis, and Bifidobacterium breve by serving as a usable carbohydrate source.
• Immune Modulation: LNB enhances antigen-specific immune responses and supports the development of the infant’s immune system.
• Metabolism: It is metabolized by bifidobacteria via a dedicated transporter and enzymatic pathway (e.g., lacto-N-biose phosphorylase), producing short-chain fatty acids beneficial for gut health.

Analytical Confirmation

• Confirmed by NMR and chromatographic methods with high purity in commercial preparations.
• Structural identity and bioactivity have been supported by biochemical and microbiological studies.

Specification Table

Related Compounds

• Lacto-N-tetraose (LNT): A tetrasaccharide formed by LNB linked to lactose, involved similarly in infant nutrition.
• Galacto-N-biose (GNB): A related disaccharide where GlcNAc is replaced by N-acetylgalactosamine, found in mucin glycans.

Lacto-N-biose is essential in infant nutrition for promoting a healthy gut microbiome and enhancing immune defense, making it valuable for infant formula supplementation and nutraceutical applications.

This description integrates chemical, biological, and functional aspects to provide a comprehensive understanding of Lacto-N-biose (LNB).

1. https://en.wikipedia.org/wiki/Lacto-N-tetraose
2. https://pubchem.ncbi.nlm.nih.gov/compound/Lacto-N-biose-II
3. https://www.glpbio.com/lacto-n-biose-i.html
4. https://www.benchchem.com/product/b043321
5. https://www.chemscene.com/applications/oligosaccharides-by-component-sugar/lacto-n-biose.html
6. https://www.sciencedirect.com/science/article/pii/S2405805X23000613
7. https://www.targetmol.com/compound/lacto-n-biose_i
8. https://www.elicityl-oligotech.com/human-milk-oligosaccharides-hmo/265-lacto-n-biose-90-hplc.html
9. https://www.medchemexpress.com/lacto-n-biose-i.html