Manninotriose is a trisaccharide composed of two galactose units and one glucose unit, with the molecular formula C₁₈H₃₂O₁₆ and a molecular weight of 504.4 g/mol. It appears as a white crystalline powder, soluble in water, methanol, ethanol, and DMSO, and occurs naturally in plants such as Rehmannia glutinosa and red deadnettle (Lamium purpureum).
This oligosaccharide belongs to the raffinose family of oligosaccharides (RFOs), sharing structural similarities with other plant-derived carbohydrates involved in energy storage and stress tolerance.
Chemical Structure
The structure of manninotriose features a linear chain in which a glucose unit links to one galactose via a glycosidic bond, while a second galactose attaches through an oxymethyl bridge. Its configuration is defined by the stereochemistry described in its IUPAC name: (2R,3S,4R,5R)-2,3,4,5-tetrahydroxy-6-[(2S,3R,4S,5R,6R)-3,4,5-trihydroxy-6-[[(2S,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]oxan-2-yl]oxyhexanal.
This chemical arrangement distinguishes manninotriose from mannotriose, which is composed solely of three mannose units. Computed physicochemical properties, including XLogP3-AA values, support its hydrophilic behavior and suitability for biological functions.
Biological Occurrence and Role
Manninotriose is a major carbohydrate in red deadnettle, where it acts as a temporary storage compound during early spring growth. It may also play a role in membrane stabilization under abiotic stress conditions.
Research highlights its involvement in raffinose family oligosaccharide metabolism, serving as a key intermediate distinct from the classic galactosylsucrose pathway. Its presence in Rehmannia glutinosa also associates it with medicinal plant metabolism.
Preparation and Applications
Enzymatic hydrolysis of stachyose is commonly used to generate manninotriose, offering high yields suitable for laboratory and industrial needs. Because Lactobacillus species preferentially metabolize related manno-oligosaccharides, manninotriose has potential applications as a prebiotic candidate.
Industrial suppliers provide manninotriose extracted from natural plant sources, supporting its use in biochemical research, carbohydrate analysis, and investigations into metabolic pathways. Its solubility and stability make it valuable for studies of plant stress responses and glycan metabolism.
