A Review of Extraction, Structural Properties, Biological Activities of Dendrobium chrysotoxum Polysaccharides

Dendrobium chrysotoxum Lindl., an important medicinal plant, contains polysaccharides (DCP) as its principal bioactive components. This review systematically outlines recent advances in the extraction, purification, structural characteristics, biological activities, and future prospects of DCP. For extraction, conventional hot water extraction followed by ethanol precipitation remains common but is limited by high energy consumption and prolonged duration. Advanced techniques, such as enzyme-assisted extraction (yielding 8.41% under optimized conditions) and a combined ultrasonic-hot water method (achieving 20.41% purity), significantly enhance efficiency. Purification generally involves deproteinization, removal of low-molecular-weight impurities, and fractionation via column chromatography to obtain homogeneous polysaccharide fractions. Structurally, DCP are heteropolysaccharides primarily consisting of glucose and mannose in varying molar ratios, with molecular weights ranging from 10⁴ to 10⁶ Da. Their backbone is mainly composed of (1→4)-linked Manp and Glcp residues, featuring branching and partial acetylation. Biologically, DCP exhibit a broad spectrum of activities, including antioxidant and anti-aging effects, immunomodulation, and organ protection. Additionally, DCP show hypoglycemic and antitumor potential, inhibiting proliferation of SPC-A-1 and HeLa cells through apoptosis induction. Despite these findings, challenges remain including inefficient extraction and insufficient understanding of the structure-activity relationships and molecular mechanisms underlying DCP's diverse biological activities. Future research should prioritize innovative extraction technologies, optimized purification, in-depth mechanistic investigations, and the development of practical applications.