Quillaja saponins, generally extracted from Quillaja saponaria tree, are considered non-ionic, high molecular weight complex glycosides known for their diverse biological and surfactant activities.
These molecules are composed of a triterpenoid aglycone lipophilic moiety and sugars (glucose, rhamnose, glucuronic acid, arabinose, and xylose) as hydrophilic moiety. The aldehyde group attached to the core aglycone binds to the free amino groups of Antigen Presenting Cells. Acyl elements of saponin can enhance the activation of CTL against exogenous antigens. The sugar chain is essential for the initiation of immune-activating mechanism. The balance between these hydrophobic and hydrophilic properties is important for maintaining the adjuvanticity of saponins.
