3'-Sialyllactose (3'-SL) is a sialylated trisaccharide composed of a lactose core (galactose linked β-1,4 to glucose) with a sialic acid residue (N-acetylneuraminic acid) attached via an α-2,3 glycosidic bond to the galactose unit. Its chemical formula is C23H39NO19, and it has a molecular weight of approximately 633.55 g/mol. This compound is naturally found in human and bovine milk as well as other mammalian colostrum.
Chemically, 3'-SL is characterized as a water-soluble, white powder with moderate solubility (~20 mg/mL in water). It differs from its isomer 6'-sialyllactose based on the position of the sialic acid linkage (3' versus 6' on the galactose). 3'-SL is stable under physiological conditions and resistant to digestion in the upper gastrointestinal tract, enabling it to reach the colon where it functions as a prebiotic.
Biological Roles of 3'-Sialyllactose
- Gut Microbiota Modulation: Supports the growth of beneficial bacteria and promotes a healthy microbial balance.
- Immune Regulation: Helps maintain immune homeostasis and supports immune system development.
- Anti-inflammatory Effects: Demonstrates anti-inflammatory and anti-arthritic properties that contribute to mucosal protection.
- Protection Against Pathogens: Inhibits pathogen adhesion to intestinal surfaces, reducing the risk of infections.
Because of these biological activities, 3'-SL is widely studied for nutritional supplementation, especially in infant formula, as well as for therapeutic applications aimed at improving gut health and immunity.
In summary, 3'-Sialyllactose is a naturally occurring sialylated oligosaccharide with important prebiotic, immunomodulatory, and anti-inflammatory properties. Its structural characteristics, biological functions, and strong safety profile make it a valuable molecule in nutrition science and biotechnology.