Ultrasound-assisted enzymatic extraction optimization of Cistanche deserticola polysaccharides, and combined analysis of the relationship between polysaccharide structure and activity by liquid chromatography and GC-MS.

Cistanche deserticola polysaccharide (CDPS) serves as a key active component in both medicinal and edible functional foods. By optimizing the enzyme ratio and ultrasonic extraction parameters, the extraction yield was raised to 23.83 %, and four fractions (CDPS-1 to CDPS-4) were obtained through graded purification. CDPS-1 features a uniform low molecular weight (989 g·mol) and a relatively high phenolic content (5.94 %). Its diverse monosaccharide composition maximizes the exposure of hydroxyl and acidic sites, thereby-together with complementary structural elements-conferring strong free radical scavenging activity at 1 mg mL conditions (81.53 % for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 44.87 % for 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)). Scanning electron microscopy (SEM) characterization reveals a layered plate-like stacking morphology, increasing the material's density and mechanical strength, thereby providing structural support for sustained antioxidant performance. Gas chromatography-mass spectrometry (GC-MS) metabolomic analysis indicates that carbohydrate metabolic pathways play a crucial role in shaping the polysaccharide structure and endowing its antioxidant properties. Overall, this study clarifies the structure-activity relationship of CDPS-1 and its underlying mechanisms, offering a theoretical basis for understanding the biological activity of Cistanche deserticola polysaccharides and providing methodological support for their standardized development in functional foods and the health industry.