Codonopsis pilosula polysaccharides: structural characteristics, structure-activity relationships, biological activities, and potential applications.

Codonopsis pilosula, a medicinal plant in the Campanulaceae family, is a classic Qi-tonifying herb in traditional Chinese medicine. Research on the pharmacological basis of its activity has spanned several decades. As pivotal active constituents, Codonopsis pilosula polysaccharides (CPPs) exhibit strong bioactivities, including immunomodulatory, antioxidant, anti-inflammatory, and antitumor effects. To date, approximately 42 homogeneous polysaccharide fractions have been reported from C. pilosula roots, with varying degrees of structural characterization depending on the analytical strategies employed. These CPP fractions exhibit considerable structural diversity in terms of molecular weight, monosaccharide composition, glycosidic linkage patterns, branching architecture, and higher-order conformations. Increasing evidence suggests that these structural characteristics contribute to their diverse biological activities; however, comprehensive understanding of the precise structural determinants underlying CPP bioactivities remains limited. This review systematically summarizes the structural characteristics and pharmacological properties of CPPs, with a specific emphasis on the structure-activity relationships (SAR) underlying their biological effects. We also clarify the molecular mechanisms responsible for their immunomodulatory and antitumor actions and discuss how structural modifications enhance efficacy through well-defined SARs.