A review of Allii macrostemonis Bulbus polysaccharides: Extraction, purification, structural characterization, and...

Allii macrostemonis Bulbus (Xiebai) is an important medicinal and edible homologous plant belonging to the genus Allium in the family Liliaceae. Its polysaccharide components (XBPS) are regarded as one of its principal bioactive constituents. Although significant progress has been made in the extraction, structural characterization, and pharmacological evaluation of XBPS, its detailed structural features, biological mechanisms of action, and structure-activity relationships remain insufficiently elucidated. This review summarizes recent advances in the extraction, purification, structural analysis, biological activities, and structural modification of XBPS, aiming to provide a theoretical foundation for its further development and application. Studies have shown that, compared with traditional hot-water extraction, emerging techniques such as ultrasound-assisted extraction offer significant advantages in enhancing extraction yield and preserving the native bioactive structures of XBPS. Structural analyses reveal that XBPS mainly comprises two types of polysaccharides: acidic polysaccharides and neutral fructans. The acidic polysaccharides are rich in uronic acids, which confer high target affinity and bioavailability, whereas the fructans primarily consist of β-(2 → 1) and β-(2 → 6) glycosidic linkages, forming a highly branched, chain-like network that serves as an important structural model for investigating structure-activity relationships. Pharmacological studies have demonstrated that XBPS exhibits a broad spectrum of biological activities, including anti-atherosclerotic, cardioprotective, anti-inflammatory, antioxidant, hepatoprotective, and antitumor effects. These biological functions are synergistically influenced by factors such as molecular weight, monosaccharide composition, glycosidic linkage type, and spatial conformation. Future research should focus on standardizing extraction and characterization methodologies, elucidating structure-function correlations, and exploring the potential applications of XBPS in the development of functional foods and pharmaceutical agents.