Advances in the Preparation, Characterization, and Bioactivity of Oligosaccharides From Traditional Chinese Medicine Polysaccharides: A Comprehensive Review

Polysaccharides in traditional Chinese medicine (TCM) are essential compounds responsible for therapeutic effects, exhibiting immunomodulatory, anti-inflammatory, and antioxidant properties. However, their high molecular weight, low solubility, and poor bioavailability restrict clinical application. Degrading these into smaller, absorbable TCM oligosaccharides (TCMOs) not only overcomes these barriers but may also enhance biological activity, offering a new avenue for high-value TCM development. This review summarizes the progress in preparing TCMOs using chemical, physical, and enzymatic methods. It outlines techniques for the separation, purification, and structural characterization of degradation products, while examining the biological activities of TCMOs in regulating gut microbiota and enhancing immunity. Enzymatic hydrolysis is established as a superior strategy for precision degradation due to its specificity and tunable kinetics. Leveraging gut microbiota-derived Polysaccharide Utilization Loci (PULs) for "bio-intelligent" preparation represents a transformative frontier for generating structurally defined TCMOs. For isolation, chromatographic platforms remain the most versatile methodologies. While the immunomodulatory effects of TCMOs are well-documented, a critical gap remains concerning structure-activity relationships in antitumor pathways and metabolic absorption. By synthesizing these insights, this review facilitates the precision customization and industrial advancement of bioactive TCMOs.